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<h1 style="max-width: 100%;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">作者：徐贤军，京东系统架构师，从事架构设计与开发工作，熟悉各种开源软件架构。在Web开发、架构优化上有较丰富实战经历。</h1> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">随着业务的复杂性增大、系统吞吐量增长，所有功能统一部署难度加大，各个功能模块相互影响，使系统变的笨重且脆弱；因此需要对业务进行拆分、对系统进行解耦、对系统内部架构升级，来提升系统容量及健壮性。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">接下来主要分两部分介绍：系统拆分与结构演变； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">系统拆分 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">系统拆分从资源角度分为：应用拆分和数据库拆分； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">从采用的先后顺序可分为：水平扩展、垂直拆分、业务拆分、水平拆分； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"><img class="" data-backh="265" data-backw="526" data-before-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3rAX225iaH9n4BIRxuR6E4Bcb6Y3qWVibz5JkTUTeR7E7BrjIU7E1pJeA/0?wx_fmt=jpeg" data-croporisrc="/upload/3ba62500dc0e80b6c130f863d812dff8.png" data-cropx1="0" data-cropx2="612" data-cropy1="39.558935361216726" data-cropy2="347.88593155893534" data-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3nsR7fTUn8TnRfqMfzOOBSwwx66YkjcHp1rZ1AMfVLomqs4mcYbCCzA/0?wx_fmt=jpeg" data-ratio="0.5032679738562091" data-type="jpeg" data-w="612" width="100%" src="https://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3nsR7fTUn8TnRfqMfzOOBSwwx66YkjcHp1rZ1AMfVLomqs4mcYbCCzA/640?wx_fmt=jpeg" style="cursor: zoom-in;box-sizing: border-box !important;word-wrap: break-word !important;visibility: visible !important;width: 634px !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">图1 系统分解原则 <h4 style="max-width: 100%;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> </h4> <h4 style="max-width: 100%;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">1、水平扩展 </h4> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">水平扩展是最初始的解决的手段，也是系统遇到瓶颈的首选方案，主要从以下两个方面扩展： <ul class=" list-paddingleft-2" style="list-style-type: circle;"> <li>应用加实例，搞集群，把系统吞吐量扩上去。</li> <li>数据库利用主从进行读写分离，数据库其实是系统最应该保护的资源。</li> </ul> <h4 style="max-width: 100%;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> </h4> <h4 style="max-width: 100%;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">2、垂直拆分</h4> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">垂直拆分才是真正开始拆分系统，主要是从业务功能角度拆分。如拆出用户系统、商品系统、交易系统等。为了解决拆分后各个子系统之间相互依赖调用的问题，这时会引入服务调用治理。系统复杂度有所加大，但系统基本解耦，稳定性相对提高，做好降级就能避免因其它系统功能异常导致系统崩溃。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">业务对应的库也会按照对应的业务进行拆分出用户库、商品库、交易库等。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <h3 style="max-width: 100%;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">3、业务拆分</h3> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">业务拆分主要是针对应用层面按功能特点拆分，如交易拆分出：购物车、结算页、订单、秒杀等系统。然后根据业务的特点，针对性做处理，如秒杀系统，由于同时参加秒杀的商品有限，可以提前把商品信息加载到JVM缓存中，自身减少外部调用提高性能，同时商品系统也减轻压力。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">数据库拆分也可以分为几步：垂直分表、垂直分库、水平分表、水平分库分表； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">垂直分表是指大表拆多张小表，可以根据字段更新或查询频次拆分； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"><img class="" data-backh="245" data-backw="526" data-before-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_png/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3WziayicI5hYO4xYlhLQ3r0Nhic84oMTkwouIdCrpOGhAT4ayLPK509oVA/0?wx_fmt=png" data-ratio="0.46471600688468157" data-type="png" data-w="581" width="100%" src="/upload/afe1e2cc96221cf21ab51e49674c6c2f.png" style="border-width: 1px;border-style: solid;border-color: rgb(238, 237, 235);cursor: zoom-in;background-color: rgb(238, 237, 235);background-size: 22px;background-position: 50% 50%;background-repeat: no-repeat;box-sizing: border-box !important;word-wrap: break-word !important;width: 634px !important;visibility: visible !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">图2 商品表拆分 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">垂直分库是指按业务拆库，如拆出订单库、商品库、用户库等 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">水平分表是解决数据量大，把一张表拆成多张表； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">水平分库分表是更进一步拆分表； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"><img class="" data-backh="134" data-backw="526" data-before-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_png/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian32ibWf04fLKRte5b3NmSeYB7WXJoVgjSZVeXeg6ydSCYrTgEW4w2OdicQ/0?wx_fmt=png" data-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3DRJU5Ny0bs4xduJy4BmNnthVhibdvjObtVsAfCfLZibTHIspb2PHz3iaA/0?wx_fmt=jpeg" data-ratio="0.25565217391304346" data-type="jpeg" data-w="575" width="100%" src="/upload/2b6d6e1d637c1199edd7bd1e79fe8b93.jpg" style="border-width: 1px;border-style: solid;border-color: rgb(238, 237, 235);cursor: zoom-in;background-color: rgb(238, 237, 235);background-size: 22px;background-position: 50% 50%;background-repeat: no-repeat;box-sizing: border-box !important;word-wrap: break-word !important;width: 634px !important;visibility: visible !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">图3 分库分表 <h3 style="max-width: 100%;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> </h3> <h3 style="max-width: 100%;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">4、水平拆分</h3> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">服务分层，系统服务积木化，拆分功能与非功能系统，以及业务组合的系统，如最近比较火的大中台或前台拆分；中台为积木组件，承担服务功能输出。前台更多的是组合积木服务，及时响应业务发展，如在电商网站单品页能看见主图、价格、库存、优惠券或推荐等信息，都是组合各积木组件呈现。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">数据库也可以进行冷热数据分离；过期或过季商品可以归档，比如诺基亚3210手机，早已经停产且没有销售；用户查看订单时，更多的只是查看最近1、2年信息，2年前数据查看量少，在存储设计时可以区别处理。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">结构演变 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">结构演变主要是随着系统复杂度增加及对性能要求提高而不得不做的系统内部架构升级； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">早期系统基本是应用直联数据库，但在系统进行拆分后，功能本系统不能单独完成，需要依赖其它系统，就出现远程调用； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"><img class="" data-backh="155" data-backw="526" data-before-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian329ZZq6FibpKNAax5UK3oJqZI6S31gTACBVpyUJt2zA4DrHRGUdxPbiag/0?wx_fmt=jpeg" data-croporisrc="/upload/ea423f75c2d817820549b27268c378b1.png" data-cropx1="0" data-cropx2="700" data-cropy1="21.292775665399237" data-cropy2="227.56653992395434" data-ratio="0.2957142857142857" data-type="jpeg" data-w="700" width="100%" src="https://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian329ZZq6FibpKNAax5UK3oJqZI6S31gTACBVpyUJt2zA4DrHRGUdxPbiag/640?wx_fmt=jpeg" style="border-width: 1px;border-style: solid;border-color: rgb(238, 237, 235);cursor: zoom-in;background-color: rgb(238, 237, 235);background-size: 22px;background-position: 50% 50%;background-repeat: no-repeat;box-sizing: border-box !important;word-wrap: break-word !important;width: 634px !important;visibility: visible !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">图4 早期应用结构 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">随着自身系统的业务发展，对性能要求高，而数据库一定程度上成为瓶颈，就会引入缓存及索引，分别解决key-value及复杂检索；索引加缓存现在已经成为解决高并发的基本方案，但在实施过程会有所区别； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">14年对3亿热数据的系统升级时，技术选型为solr+redis，考虑到数据量过大，数据在solr中只存index，而结果只存并返回主键id，再通过id从redis中读取数据，redis也不存放全部数据，数据设置过期时间，若未命中redis，回源数据库查询并反写redis；主要考虑资源与性能的平衡，solr的存储减少及IO性能提高，结果数据只在redis存放一份，redis的数据经过运行大部分是热数据；当然现在也流行ES+Hbase组合。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"><img class="" data-backh="198" data-backw="526" data-before-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian30ibiaMLcl03RPZyIc9bgHI5xfd1J6oJ8iaLEMuNxxPIwDQgby5q1oiaUyw/0?wx_fmt=jpeg" data-croporisrc="/upload/9b33efac08009bc2403b8583698eaf1a.png" data-cropx1="0" data-cropx2="700" data-cropy1="0" data-cropy2="263.4980988593156" data-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3eaM9yF9ZcBJGCZnR08HhXms97l9vplO1iah6l6xfKwRtX0CkGh1SOSg/0?wx_fmt=jpeg" data-ratio="0.3757142857142857" data-type="jpeg" data-w="700" width="100%" src="https://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3eaM9yF9ZcBJGCZnR08HhXms97l9vplO1iah6l6xfKwRtX0CkGh1SOSg/640?wx_fmt=jpeg" style="border-width: 1px;border-style: solid;border-color: rgb(238, 237, 235);cursor: zoom-in;background-color: rgb(238, 237, 235);background-size: 22px;background-position: 50% 50%;background-repeat: no-repeat;box-sizing: border-box !important;word-wrap: break-word !important;width: 634px !important;visibility: visible !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">图5 增加缓存及索引 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">对于频繁使用的数据，从集中缓存读取，不一定达到性能要求，可以考虑把数据入JVM缓存，如类目信息，类目是电商系统基本数据，数据量不多，调用量大； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">个别情况下，使用ThreadLocal做线程内缓存也是种有效手段，但需要考虑数据清除及有效性； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">在修改商品信息时，业务对商品信息的校验有名称长度、状态、库存及各业务模式等，而为了参数的统一校验方法参数为商品编号，导致各校验方法都需要读取一次商品，使用线程缓存可以解决该问题，性能提高了尽20ms，读取商品每分钟减少近万次； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"><img class="" data-backh="189" data-backw="526" data-before-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_png/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian32l8IqdVztAVqhRJKibarBuU1INyE6BbiayL0o9hav66gJos1RIFvGueQ/0?wx_fmt=png" data-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian39RNdZj1aAl7xIEia7GXnvsqrPcRL7a6PkgcHRv8yxznUrB4m7G005ew/0?wx_fmt=jpeg" data-ratio="0.3585714285714286" data-type="jpeg" data-w="700" width="100%" src="/upload/fe63a2a30eb10f4f8ae87f7fdb761af3.jpg" style="border-width: 1px;border-style: solid;border-color: rgb(238, 237, 235);cursor: zoom-in;background-color: rgb(238, 237, 235);background-size: 22px;background-position: 50% 50%;background-repeat: no-repeat;box-sizing: border-box !important;word-wrap: break-word !important;width: 634px !important;visibility: visible !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">图6 增加本地缓存 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">有时所依赖系统性能不太稳定，避免出现因第三方系统影响系统，把依赖的服务进行数据闭环，与Dao一样当成系统的数据源；如商品系统强依赖商家系统的商家信息服务，若商家服务不稳定，商品系统一半服务都不稳定，采取对商家信息缓存一份，降低外部风险，把风险控制在自己手上； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"><img class="" data-backh="298" data-backw="453" data-before-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_png/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3AiaY1TPmWeE41ZxxRWqLrGiaI1okI0G30cLtNjQzicINt4ElVaEMLibVsg/0?wx_fmt=png" data-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_jpg/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3RbWWvCYZYE6VGOzjpJZtzC5D2yGlpp1TMSBoZDUkcZUoNKicNlADyBw/0?wx_fmt=jpeg" data-ratio="0.6578366445916115" data-type="jpeg" data-w="453" width="100%" src="/upload/2a631c7c085c8860043c0a93d6137fda.jpg" style="border-width: 1px;border-style: solid;border-color: rgb(238, 237, 235);cursor: zoom-in;background-color: rgb(238, 237, 235);background-size: 22px;background-position: 50% 50%;background-repeat: no-repeat;box-sizing: border-box !important;word-wrap: break-word !important;width: 634px !important;visibility: visible !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">图7 远程服务进化成数据源 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">用户体验最近越来越重视，系统响应时间性能要求也越来越高，异步化是很好的一种选择：消息中间件；电商下单就是个很好的案例，在用户点击下单时，服务端不直接保存数据，给订单系统发送消息，就直接返回支付页面，在用户支付过程中，订单系统异步进行数据保存； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">业务层、数据层的范围越来越宽泛，业务层可以分为基础服务与组合服务；数据层分为数据源与索引缓存；依赖的技术或中间件需要有效的结合，用于解决系统所遇到各种问题。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"><img class="" data-backh="326" data-backw="526" data-before-oversubscription-url="http://mmbiz.qpic.cn/mmbiz_png/RQv8vncPm1Xm03mhN0XFxDiawnbpBmian3FJGgcgdWKw8puVbWnxaha0u320TnoLgzQ6MOgBiaicY71BpEhVQXicjow/0?wx_fmt=png" data-ratio="0.62" data-type="png" data-w="700" width="100%" src="/upload/8933a91afd77a42e6334cf6a4fe2a7f4.png" style="cursor: zoom-in;box-sizing: border-box !important;word-wrap: break-word !important;visibility: visible !important;width: 634px !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">图8 复杂的结构 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">最后 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">系统结构慢慢变复杂，稳定性、健壮性逐渐提高；技术选择都需要结合业务痛点、技术储备以及资源情况，否则就有些不切实际，泛泛而谈； <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">以上是近几年自己经历的技术变革及升级的总结，后续可以针对个别点进行详细分享。 <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;"> <p style="max-width: 100%;min-height: 1em;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;letter-spacing: 0.544px;text-align: justify;white-space: normal;background-color: rgb(255, 255, 255);box-sizing: border-box !important;word-wrap: break-word !important;">系统拆分的最后是微服务，结构的演变是技术的升级。 <section class="_135editor" data-tools="135编辑器" data-id="85996" style="border-width: 0px;border-style: none;border-color: initial;box-sizing: border-box;"> <section style="text-align:center;"> <section style="background-color: rgb(244, 244, 244);box-sizing: border-box;padding: 40px;"> <section style="margin-bottom: 10px;"> Java高级架构 ∣ 干货｜学习 </section> <section> <section style="display:inline-block;vertical-align: top;margin-top: 14px;width: 50%;text-align: right;" data-width="50%"> <img border="0" class="" data-ratio="0.993993993993994" src="/upload/b65b49bf5b4b93db5800dd70c5faae54.png" data-type="png" data-w="666" height="auto" opacity="" style="width: 120px;" title="" width="120"> </section> <section style="display:inline-block;box-sizing:border-box;padding-left: 10px;width: 50%;text-align: left;" data-width="50%"> <img class="" data-ratio="1.39" src="/upload/9d2924f9c5be1305d2d10457a2988b10.png" data-type="png" data-w="100" style="width: 100px;"> </section> </section> <section style="margin-top: 6px;"> 长按，识别二维码，加关注 </section> </section> </section> </section> <section class="_135editor" data-id="image-96175" style="border-width: 0px;border-style: none;border-color: initial;box-sizing: border-box;"> <section class="_135editor" data-tools="135编辑器" data-id="92353" style="border-width: 0px;border-style: none;border-color: initial;box-sizing: border-box;"> <section data-role="paragraph" class="_135editor" style="border-width: 0px;border-style: none;border-color: initial;box-sizing: border-box;"> <section style="padding: 10px;box-sizing: border-box;"> <section style="width: 130px;height: 30px;background-image: url("https://mmbiz.qpic.cn/mmbiz_png/YUYc62VIvE3b2VMiaHflzgF5hnfMCLxJTkrFYUGlTFoTrHpo6WpYpGgAUsdmPdzS2icibeQWiaLTPEUY5t4RqUYp0Q/640?wx_fmt=png");background-size: 100%;background-repeat: no-repeat;background-position: center center;margin-left: 25px;transform: translateZ(10px);"> <section style="width: 118px;height: 30px;text-align: center;line-height: 30px;color: #fefefe;letter-spacing: 3px;"> 温馨提示 </section> </section> <section style="box-shadow: rgb(204, 204, 204) 0px 0px 7px;border-radius: 15px;color: rgb(51, 51, 51);padding: 15px;margin-top: -20px;box-sizing: border-box;"> <section style="line-height: 25px;margin-top: 15px;font-size: 14px;" class="135brush"> 如果你喜欢本文，请分享到朋友圈，想要获得更多信息，请关注我。关注本文说说你的看法吧，下方评论哦 </section> </section> </section> </section> </section> </section>

可能是最易懂的Hbase架构原理解析

作者：微信小助手

<section style="box-sizing: border-box;font-size: 16px;"> <section style="box-sizing: border-box;" powered-by="xiumi.us"> <section style="margin-top: 10px;margin-bottom: 10px;box-sizing: border-box;"> <section style="padding-top: 10px;padding-right: 10px;padding-left: 10px;box-sizing: border-box;background-color: rgb(239, 239, 239);"> <section style="box-sizing: border-box;"> “ </section> <section style="display: inline-block;vertical-align: top;float: right;width: 90%;line-height: 1.5;font-size: 15px;color: rgb(89, 89, 89);box-sizing: border-box;"> 小史是一个非科班的程序员，虽然学的是电子专业，但是通过自己的努力成功通过了面试，现在要开始迎接新生活了。 </section> <section style="clear: both;box-sizing: border-box;"></section> </section> </section> </section> </section> <img class="rich_pages" data-copyright="0" data-ratio="0.4793491864831039" data-s="300,640" src="/upload/9bc576dde2c6c5e2327b035ca31ccf6a.png" data-type="png" data-w="799" style=""> <img style="width: 558px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/2ff1805dda7d70892bb3f61234ae0ac2.jpg" data-w="558" data-type="jpeg" data-s="300,640" data-ratio="0.44802867383512546" data-copyright="0"> <img style="width: 533px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/adf72567cdcb4513d6f75d30e8e73870.jpg" data-w="533" data-type="jpeg" data-s="300,640" data-ratio="0.5628517823639775" data-copyright="0"> 今天，小史的姐姐和吕老师一起过来看小史，一进屋，就有一股难闻的气味。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/c2517567526fc0a158348d9db22ade43.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/a5a23a7cc54a8895a1f29bb7574df1c1.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 可不，小史姐姐走进卫生间，发现地下一个盆子里全是没洗的袜子。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/b1021b4b31f9399929d25d2c3d7428a1.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="letter-spacing: 0.54px;width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/db5c1c1abfc1f72e10e1d12e495d9b7e.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 小史：当然不是，盆里的袜子满了，就先放到这个桶里，然后再继续装，等到桶里的袜子满了，然后才放到洗衣机里一次洗完，这样不仅效率高，而且节省水电费。 <img style="width: 424px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/b782adb2df9ad723a9c808fc245d5c88.jpg" data-w="424" data-type="jpeg" data-s="300,640" data-ratio="1.1367924528301887" data-copyright="0"> 小史洋洋得意地介绍起自己洗袜子的流程。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/eab82ff9e58bb9916b07e97c75bf1101.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 小史一听就有点不高兴，全世界都黑程序员，没想到自己还没变成程序员就被自家姐姐黑了。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/dc760c7e487926a011c531db2d964e55.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 说完就进自己房间，把姐姐和吕老师晾在外面。小史姐姐也意识到不该拿程序员开玩笑，但现在也不知道该怎么办，就看着吕老师。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/657c4ec6868ef476817c0417a4966279.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师走进小史的房间。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/c8423f5b719395365367cf2fc87aa233.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/41c1eeaa983b6418ecc8f287460e330e.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <section style="box-sizing: border-box;font-size: 16px;"> <section style="box-sizing: border-box;" powered-by="xiumi.us"> <section style="border-bottom-width: 1px;border-bottom-style: solid;border-bottom-color: black;margin-top: 0.5em;margin-bottom: 0.5em;line-height: 1.2;box-sizing: border-box;"> <section style="display: inline-block;border-bottom-width: 6px;border-bottom-style: solid;border-color: rgb(89, 89, 89);margin-bottom: -1px;font-size: 20px;color: rgb(89, 89, 89);box-sizing: border-box;"> HBase是啥 </section> </section> </section> </section> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/196744ac7b7875c71b454898965060c7.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/bc0866662a3d9bc5add404833a4ceb32.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 小史：别吹了，构建在 HDFS 上除了能存储海量数据之外，缺点一大堆，上次你给我介绍的 HDFS 缺点我可没忘啊，不支持小文件，不支持并发写，不支持文件随机修改，查询效率也低。 小史仔细回忆起 HDFS 来： <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/d86d6d6ea1f1c321c6022b6fb2eb9350.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：HDFS 确实有很多缺点，但是 HBase 却是一个支持百万级别高并发写入，支持实时查询，适合存储稀疏数据的分布式数据库系统。 <img style="letter-spacing: 0.54px;width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/55248c7bbc391f678084a840ae564732.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/e785a07dae4be08d5ffa0db21e3f83fb.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：HBase 主要用于大数据领域，在这方面，确实比 MySQL 要厉害得多啊，它和 MySQL 的存储方式就完全不一样。MySQL 是行式存储，HBase 是列式存储。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/6230b75b9e8f8de80daf0f7d5835b223.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <section style="box-sizing: border-box;font-size: 16px;"> <section style="box-sizing: border-box;" powered-by="xiumi.us"> <section style="border-bottom-width: 1px;border-bottom-style: solid;border-bottom-color: black;margin-top: 0.5em;margin-bottom: 0.5em;line-height: 1.2;box-sizing: border-box;"> <section style="display: inline-block;border-bottom-width: 6px;border-bottom-style: solid;border-color: rgb(89, 89, 89);margin-bottom: -1px;font-size: 20px;color: rgb(89, 89, 89);box-sizing: border-box;"> 列式存储 </section> </section> </section> </section> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/b89acce1109d99f524d35d5a28079be3.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 402px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/cf70d6fc6c59e618226e6f877f793bd5.jpg" data-w="402" data-type="jpeg" data-s="300,640" data-ratio="1.0422885572139304" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/fc8e96edc189e8740e7c71bc828172a1.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/69a07ee62d6fc67c01d8f27e0c5da670.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/aeb3fa4f27e9fb4f8314f87b9095c198.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 424px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/420e41aea11b6b07fb70be7925a47047.jpg" data-w="424" data-type="jpeg" data-s="300,640" data-ratio="0.8632075471698113" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/16dc47263b6af7c1e3d58ba82ddb8bcc.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/128efa0757ec48d398ec0cd8846572ec.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/edeeb3654f64e397e201201eadc992f6.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：没错，这就是行式存储系统存储稀疏数据的问题，我们再来看看列式存储如何解决这个问题，它的存储结构是这样的： <img style="width: 402px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/1ddea2ee698e904bea6e89ebb8c99ea7.jpg" data-w="402" data-type="jpeg" data-s="300,640" data-ratio="1.291044776119403" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/8ea9d94c2dedacb1773b74a34da63d48.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 小史：这个我看懂了，相当于把每一行的每一列拆开，然后通过 Rowkey 关联起来，Rowkey 相同的这些数据其实就是原来的一行。 <img style="letter-spacing: 0.54px;width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/810e6b44d17649bb6d4b3d7268d86367.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="letter-spacing: 0.54px;width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/94039cbf60e5bd56e68be388fb853665.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/8303d1a5519eb22350053e021a695be5.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：你这里只说到了一个好处，由于把一行数据变成了这样的 key-value 的形式。 所以 HBase 可以存储上百万列，又由于 HBase 基于 HDFS 来存储，所以 HBase 可以存储上亿行，是一个真正的海量数据库。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/b9647c52102c6f4ca12f960343647da7.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/e704eaef988ab1a9f5efb4a82820eaa8.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：这就是 HBase 的威力呀，还不只如此，其实很多时候，我们做 Select 查询的时候，只关注某几列，比如我现在只关心大家的工资，传统的按行存储，要选出所有人的工资是怎么办的呢？ <img style="letter-spacing: 0.54px;width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/938980f53b2e2d60c3a24b6c38d3c30e.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 424px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/4070d14d827dddfb77814451940a2bc5.jpg" data-w="424" data-type="jpeg" data-s="300,640" data-ratio="1.2311320754716981" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/21677eb7d4260afe4df9ac526e148486.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 402px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/dbd1fceccdda0ba668627dd54e1276f.jpg" data-w="402" data-type="jpeg" data-s="300,640" data-ratio="1.291044776119403" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/cd01776bfbb3969b08dd70d400d09662.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 小史：哦，我大概明白了，原来是这样，所以 HBase 的查询效率也很高，但是我有个问题啊，如果我就要查我的所有信息，这是一行数据，HBase 查询起来是不是反而更慢了呢？ <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/f4aa05a68064bea3a16aa23b4c6192a0.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <section style="box-sizing: border-box;font-size: 16px;"> <section style="box-sizing: border-box;" powered-by="xiumi.us"> <section style="border-bottom-width: 1px;border-bottom-style: solid;border-bottom-color: black;margin-top: 0.5em;margin-bottom: 0.5em;line-height: 1.2;box-sizing: border-box;"> <section style="display: inline-block;border-bottom-width: 6px;border-bottom-style: solid;border-color: rgb(89, 89, 89);margin-bottom: -1px;font-size: 20px;color: rgb(89, 89, 89);box-sizing: border-box;"> 列簇 </section> </section> </section> </section> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/43ee467fe5fa3e6d883d5b654ab54cb8.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：列簇，顾名思义，就是把一些列放在一起咯，在 HBase 中，会把列簇中的列存储在一起，比如我们把和工作相关的 Salary 和 Job 都放在 Work 这个列簇下。 那么大概是这样的： <img style="width: 402px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/964a293602bacd2557033d58347fae0f.jpg" data-w="402" data-type="jpeg" data-s="300,640" data-ratio="1.318407960199005" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/3793c0e065d78712ae2cbd615e7efdf2.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="letter-spacing: 0.54px;width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/42216a577b33294b8a5ee670d4bcebbc.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 402px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/45c85bd237f95d31e5f808ada269a35d.jpg" data-w="402" data-type="jpeg" data-s="300,640" data-ratio="1.291044776119403" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/a28050d4131b38dda1e4ca2d6dd1ed0e.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 小史：哦，我明白了，这样的话，一个列簇中的列会被一次就拿出来，如果我要查所有列的信息的话，把所有信息都放在一个列簇就好了。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/a1ea5e6593822379c5b435637bfd4b36.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 注意：HBase 中，其实所有列都是在列簇中，定义表的时候就需要指定列簇。生产环境由于性能考虑和数据均衡考虑，一般只会用一个列簇，最多两个列簇。 <section style="box-sizing: border-box;font-size: 16px;"> <section style="box-sizing: border-box;" powered-by="xiumi.us"> <section style="border-bottom-width: 1px;border-bottom-style: solid;border-bottom-color: black;margin-top: 0.5em;margin-bottom: 0.5em;line-height: 1.2;box-sizing: border-box;"> <section style="display: inline-block;border-bottom-width: 6px;border-bottom-style: solid;border-color: rgb(89, 89, 89);margin-bottom: -1px;font-size: 20px;color: rgb(89, 89, 89);box-sizing: border-box;"> Rowkey 设计 </section> </section> </section> </section> <img style="letter-spacing: 0.54px;width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/52ac8fa82839bde71e1f706a6b2d2ed.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/80073af02dfd0b0af32db5c3d47bada2.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 注：当然，有些中间件把 SQL 翻译成 HBase 的查询规则，从而支持了 SQL 查 HBase，不在本文讨论范围内。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/e095ef412773ae7809e1155965087209.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 小史：啊？这和我想象的不一样啊，如果我想查询工资比 20w 多的记录，在 MySQL 中，只要用一条很简单的 SQL 就行啊，这在 HBase 中怎么查呢？ <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/a5ee32665208be4c1b6fd4928143699a.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：在 HBase 中，你需要把要查询的字段巧妙地设置在 Rowkey 中，一个 Rowkey 你可以理解为一个字符串，而 HBase 就是根据 Rowkey 来建立索引的。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/bb963b17223108fd2c67f56295dfc692.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/51a9bb523766c5be838c8feb19f78d4.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 不熟悉 B+ 树的同学可以看<a href="http://mp.weixin.qq.com/s?__biz=MjM5ODI5Njc2MA==&mid=2655823045&idx=1&sn=4b26147c86a456f3dc9e738cad9f5051&chksm=bd74e9128a0360049bac7b6c7d210f682f0361223967fc1642e69c2fe6fed8325fca6398149b&scene=21#wechat_redirect" target="_blank" data-itemshowtype="0" data-linktype="2">这篇文章</a>。<a href="http://mp.weixin.qq.com/s?__biz=MzIzMTE1ODkyNQ==&mid=2649410831&idx=1&sn=6f7a44307403ceab496334bc828ddd06&chksm=f0b608edc7c181fb2569e4174652174134eaa22500e6a3424f6930fcd5799d82a08ec30b45d2&scene=21#wechat_redirect" target="_blank" data-linktype="2"></a>HBase 的 HFile 底层也是一样的原理。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/94f39893cbe481ed416caa3e3eece214.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/43cab67637759d4226f2b8910ffd7507.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：假设员工工资 9999w 封顶，查询的时候可能根据员工工资查询，也可能根据名字查询一个特定的员工，那么 Rowkey 就可以这样设计： <img style="width: 402px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/956f73ad03e34a219d3e723be36ce87f.jpg" data-w="402" data-type="jpeg" data-s="300,640" data-ratio="1.318407960199005" data-copyright="0"> 注意：以上 Rowkey 是简化版设计，只是为了讲清楚范围查询。实际使用中由于 Rowkey 需要考虑散列性，所以可能不会这么用。后文会具体探讨散列性。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/fec48ee928ec80013701099537f7e34a.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/e8d72a46ae14783e8031f6a51cc259e6.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：HBase 提供了三种查询方式： <ul class=" list-paddingleft-2" style="list-style-type: disc;"> <li>全表扫描，Scan。</li> <li>根据一个 Rowkey 进行查询。</li> <li>根据 Rowkey 过滤的范围查询。</li> </ul> 比如你要查工资不少于 20w 的记录，就可以用范围查询，查出从 startRow=0020 到 stopRow=9999 的所有记录，这是 HBase 直接支持的一种查询方式哦。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/5044383a740a7bc22069ab01e9266422.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 吕老师：这里要注意几点，首先，Rowkey 是按照字符串字典序来组织成 B+ 树的，所以数字的话需要补齐，不然的话会出现 123w 小于 20w 的情况，但是补齐的话，你就会发现 020w 小于 123w。 <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/d02a79ec2d02a52e41e858a8d409d7c0.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> <img style="width: 448px !important;visibility: visible !important;word-wrap: break-word !important;box-sizing: border-box !important;" src="/upload/9f128f7eea680f76cb51268212b50b9c.jpg" data-w="448" data-type="jpeg" data-s="300,640" data-ratio="1.0223214285714286" data-copyright="0"> 小史：哦，明白了，这都很好理解，因为 Rowkey 是字符串形式，所以肯定是按照字符串顺序排序咯。 而且 Rowkey 有点类似于 MySQL 中的主键吧，所以保证其唯一性也是可以理解的。 还有就是因为每个 key-value 都包含 Rowkey，所以 Rowkey 越短，越能节省存储空间。 <img style="width: 448px !importan

回调“地狱”与反应模式

作者：微信小助手

<hr style="border-style: solid;border-width: 1px 0 0;border-color: rgba(0,0,0,0.1);-webkit-transform-origin: 0 0;-webkit-transform: scale(1, 0.5);transform-origin: 0 0;transform: scale(1, 0.5);"> <section class="_editor"> <section style="margin: 10px 0%;text-align: center;"> <section style="display: inline-block;vertical-align: middle;width: 80%;padding-left: 10px;box-sizing: border-box;" data-width="80%"> <section style="box-sizing: border-box;"> <section style="color: #fa7f7f;box-sizing: border-box;"> 点击左上角蓝字，关注“锅外的大佬”<img src="/upload/3e8e6f059ad3a6eaf4bb1a86e5aba133.gif" data-type="gif" data-width="44%" style="font-size: 17px;vertical-align: middle;width: 25px;height: 29px;" class="" data-ratio="1.1625" data-w="80"> </section> </section> </section> </section> </section> <section class="_editor"> 专注分享国外最新技术内容 </section> <section class="layout" style="font-size: 16px;color: black;padding: 10px;line-height: 1.6;letter-spacing: 0px;overflow-wrap: break-word;font-family: Optima-Regular, Optima, PingFangSC-light, PingFangTC-light, "PingFang SC", Cambria, Cochin, Georgia, Times, "Times New Roman", serif;word-break: break-all;background-image: linear-gradient(90deg, rgba(50, 0, 0, 0.05) 3%, rgba(0, 0, 0, 0) 3%), linear-gradient(360deg, rgba(50, 0, 0, 0.05) 3%, rgba(0, 0, 0, 0) 3%);background-size: 20px 20px;background-position: center center;"> 了解更多有关基于反应流的方法以及如何避免回调地狱的信息。 更好地理解基于反应流的方法的有用性的方法之一是它如何简化非阻塞 IO 调用。 本篇文章将简要介绍进行同步远程调用所涉及的代码类型。然后，我们将演示非阻塞 IO 中的分层如何高效使用资源（尤其是线程），引入了称为回调地狱带来的复杂性以及基于反应流方法如何简化编程模型。 <h2 style="margin-top: 20px;margin-bottom: 10px;font-weight: bold;border-bottom: 2px solid rgb(239, 112, 96);font-size: 1.3em;">1. 目标服务 </h2> 客户端调用表示城市详细信息的目标服务有两个端口。当使用类型为——/cityids 的 URI 调用时，返回城市 id 列表，并且示例结果如下所示： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="json"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">[</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> 1,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> 2,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> 3,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> 4,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> 5,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> 6,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> 7</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">]</code></pre> </section> 一个端口返回给定其 ID 的城市的详细信息，例如，当使用 ID 为1——“/cities/1” 调用时： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="json"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">{</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> "country": "USA",</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> "id": 1,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> "name": "Portland",</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> "pop": 1600000</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}</code></pre> </section> 客户端的责任是获取城市 ID 的列表，然后对于每个城市，根据 ID 获取城市的详细信息并将其组合到城市列表中。 <h2 style="margin-top: 20px;margin-bottom: 10px;font-weight: bold;border-bottom: 2px solid rgb(239, 112, 96);font-size: 1.3em;">2. 同步调用 </h2> 我正在使用 Spring Framework 的 RestTemplate 进行远程调用。获取 cityId 列表的 Kotlin 函数如下所示： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">private fun getCityIds(): List<String> {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val cityIdsEntity: ResponseEntity<List<String>> = restTemplate</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .exchange("http://localhost:$localServerPort/cityids",</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> HttpMethod.GET,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> null,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> object : ParameterizedTypeReference<List<String>>() {})</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> return cityIdsEntity.body!!</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}</code></pre> </section> 获取城市详情： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">private fun getCityForId(id: String): City {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> return restTemplate.getForObject("http://localhost:$localServerPort/cities/$id", City::class.java)!!</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}</code></pre> </section> 鉴于这两个函数，它们很容易组合，以便于轻松返回城市列表： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">val cityIds: List<String> = getCityIds()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">val cities: List<City> = cityIds</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .stream()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .map<City> { cityId -> getCityForId(cityId) }</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .collect(Collectors.toList())</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">cities.forEach { city -> LOGGER.info(city.toString()) }</code></pre> </section> 代码很容易理解；但是，涉及八个阻塞调用： <ol style="" class=" list-paddingleft-2"> <li>获取 7 个城市 ID 的列表，然后获取每个城市的详细信息</li> <li>获取 7 个城市的详细信息</li> </ol> 每一个调用都将在不同的线程上。 <h2 style="margin-top: 20px;margin-bottom: 10px;font-weight: bold;border-bottom: 2px solid rgb(239, 112, 96);font-size: 1.3em;">3. 非阻塞 IO 回调 </h2> 我将使用 AsyncHttpClient 库来进行非阻塞 IO 调用。 进行远程调用时，<code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">AyncHttpClient</code> 返回 ListenableFuture 类型。 <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">val responseListenableFuture: ListenableFuture<Response> = asyncHttpClient</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .prepareGet("http://localhost:$localServerPort/cityids")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .execute()</code></pre> </section> 可以将回调附加到 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">ListenableFuture</code> 以在可用时对响应进行操作。 <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">responseListenableFuture.addListener(Runnable {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val response: Response = responseListenableFuture.get()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val responseBody: String = response.responseBody</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val cityIds: List<Long> = objectMapper.readValue<List<Long>>(responseBody,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> object : TypeReference<List<Long>>() {})</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> ....</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}</code></pre> </section> 鉴于 cityIds 的列表，我想获得城市的详细信息，因此从响应中，我需要进行更多的远程调用并为每个调用附加回调以获取城市的详细信息： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">val responseListenableFuture: ListenableFuture<Response> = asyncHttpClient</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .prepareGet("http://localhost:$localServerPort/cityids")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .execute()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">responseListenableFuture.addListener(Runnable {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val response: Response = responseListenableFuture.get()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val responseBody: String = response.responseBody</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val cityIds: List<Long> = objectMapper.readValue<List<Long>>(responseBody,</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> object : TypeReference<List<Long>>() {})</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> cityIds.stream().map { cityId -></code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val cityListenableFuture = asyncHttpClient</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .prepareGet("http://localhost:$localServerPort/cities/$cityId")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .execute()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> cityListenableFuture.addListener(Runnable {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val cityDescResp = cityListenableFuture.get()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val cityDesc = cityDescResp.responseBody</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val city = objectMapper.readValue(cityDesc, City::class.java)</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> LOGGER.info("Got city: $city")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }, executor)</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }.collect(Collectors.toList())</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}, executor)</code></pre> </section> 这是一段粗糙的代码；回调中又包含一组回调，很难推理和理解 - 因此它被称为“回调地狱”。 <h2 style="margin-top: 20px;margin-bottom: 10px;font-weight: bold;border-bottom: 2px solid rgb(239, 112, 96);font-size: 1.3em;">4. 在 Java CompletableFuture 中使用非阻塞 IO </h2> 通过将 Java 的 CompletableFuture 作为返回类型而不是 ListenableFuture 返回，可以稍微改进此代码。<code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">CompletableFuture</code> 提供允许修改和返回类型的运算符。 例如，考虑获取城市 ID 列表的功能： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">private fun getCityIds(): CompletableFuture<List<Long>> {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> return asyncHttpClient</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .prepareGet("http://localhost:$localServerPort/cityids")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .execute()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .toCompletableFuture()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .thenApply { response -></code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val s = response.responseBody</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val l: List<Long> = objectMapper.readValue(s, object : TypeReference<List<Long>>() {})</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> l</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}</code></pre> </section> 在这里，我使用 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">thenApply</code> 运算符将 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">CompletableFuture<Response></code> 转换为 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">CompletableFuture<List<Long>></code> 。 同样的，获取城市详情： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">private fun getCityDetail(cityId: Long): CompletableFuture<City> {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> return asyncHttpClient.prepareGet("http://localhost:$localServerPort/cities/$cityId")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .execute()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .toCompletableFuture()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .thenApply { response -></code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val s = response.responseBody</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> LOGGER.info("Got {}", s)</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val city = objectMaper.readValue(s, City::class.java)</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> city</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}</code></pre> </section> 这是基于回调的方法的改进。但是，在这个特定情况下，<code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">CompletableFuture</code> 缺乏有用的运算符，例如，所有城市细节都需要放在一起： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">val cityIdsFuture: CompletableFuture<List<Long>> = getCityIds()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">val citiesCompletableFuture: CompletableFuture<List<City>> =</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> cityIdsFuture</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .thenCompose { l -></code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val citiesCompletable: List<CompletableFuture<City>> =</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> l.stream()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .map { cityId -></code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> getCityDetail(cityId)</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }.collect(toList())</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val citiesCompletableFutureOfList: CompletableFuture<List<City>> = CompletableFuture.allOf(*citiesCompletable.toTypedArray())</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .thenApply { _: Void? -></code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> citiesCompletable</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .stream()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .map { it.join() }</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .collect(toList())</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> citiesCompletableFutureOfList</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }</code></pre> </section> 使用了一个名为 CompletableFuture.allOf 的运算符，它返回一个“Void”类型，并且必须强制返回所需类型的 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">CompletableFuture<List<City>></code>。 <h2 style="margin-top: 20px;margin-bottom: 10px;font-weight: bold;border-bottom: 2px solid rgb(239, 112, 96);font-size: 1.3em;">5. 使用 Reactor 项目 </h2> Project Reactor 是 Reactive Streams 规范的实现。它有两种特殊类型可以返回 0/1 项的流和 0/n 项的流 - 前者是 Mono，后者是 Flux。 Project Reactor 提供了一组非常丰富的运算符，允许以各种方式转换数据流。首先考虑返回城市 ID 列表的函数： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">private fun getCityIds(): Flux<Long> {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> return webClient.get()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .uri("/cityids")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .exchange()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .flatMapMany { response -></code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> LOGGER.info("Received cities..")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> response.bodyToFlux<Long>()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}</code></pre> </section> 我正在使用 Spring 优秀的 WebClient 库进行远程调用并获得 Project Reactor <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">Mono <ClientResponse></code> 类型的响应，可以使用 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">flatMapMany</code> 运算符将其修改为 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">Flux<Long></code> 类型。 根据城市 ID，沿着同样的路线获取城市的详情： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">private fun getCityDetail(cityId: Long?): Mono<City> {</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> return webClient.get()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .uri("/cities/{id}", cityId!!)</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .exchange()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .flatMap { response -></code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> val city: Mono<City> = response.bodyToMono()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> LOGGER.info("Received city..")</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> city</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> }</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">}</code></pre> </section> 在这里，Project Reactor <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">Mono<ClientResponse></code> 类型正在使用 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">flatMap</code> 运算符转换为 <code style="font-size: 14px;overflow-wrap: break-word;padding: 2px 4px;border-radius: 4px;margin-right: 2px;margin-left: 2px;background-color: rgba(27, 31, 35, 0.05);font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(239, 112, 96);">Mono<City></code> 类型。 以及从中获取 cityIds，这是 City 的代码： <section class="code-snippet__fix code-snippet__js"> <ul class="code-snippet__line-index code-snippet__js"> <li></li> <li></li> <li></li> <li></li> </ul> <pre class="code-snippet__js" data-lang="kotlin"><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">val cityIdsFlux: Flux<Long> = getCityIds()</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">val citiesFlux: Flux<City> = cityIdsFlux</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); "> .flatMap { this.getCityDetail(it) }</code><code style=" border-radius: 0px;padding: 2px;text-align: left;white-space: pre;display: flex; font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;background: rgba(0, 0, 0, 0); ">return citiesFlux</code></pre> </section> 这非常具有表现力 - 对比基于回调的方法的混乱和基于 Reactive Streams 的方法的简单性。 <h2 style="margin-top: 20px;margin-bottom: 10px;font-weight: bold;border-bottom: 2px solid rgb(239, 112, 96);font-size: 1.3em;">6. 结束语 </h2> 在我看来，这是使用基于反应流的方法的最大原因之一，特别是 Project Reactor，用于涉及跨越异步边界的场景，例如在此实例中进行远程调用。它清理了回调和回调的混乱，提供了一种使用丰富的运算符进行修改/转换类型的自然方法。 本文使用的所有示例的工作版本的存储库都可以在 GitHub 上找到。 <blockquote style="font-size: 0.9em;overflow: auto;color: rgb(106, 115, 125);padding: 10px 10px 10px 20px;margin-bottom: 20px;margin-top: 20px;border-left-color: rgb(239, 112, 96);background: rgb(239, 235, 233);"> 原文：https://dzone.com/articles/callback-hell-and-reactive-patterns </blockquote> <blockquote style="font-size: 0.9em;overflow: auto;color: rgb(106, 115, 125);padding: 10px 10px 10px 20px;margin-bottom: 20px;margin-top: 20px;border-left-color: rgb(239, 112, 96);background: rgb(239, 235, 233);"> 作者：Biju Kunjummen </blockquote> <blockquote style="font-size: 0.9em;overflow: auto;color: rgb(106, 115, 125);padding: 10px 10px 10px 20px;margin-bottom: 20px;margin-top: 20px;border-left-color: rgb(239, 112, 96);background: rgb(239, 235, 233);"> 译者：Emma<span style="text-align: center;color: rgb(51, 51, 51);font-family: -apple-system-font, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei UI", "Microsoft YaHei", Arial, sans-serif;font-size: 17px;">  </blockquote> </section> 推荐阅读： <a href="http://mp.weixin.qq.com/s?__biz=MzIzNzYxNDYzNw==&mid=2247483905&idx=1&sn=af56c9108b5f0998e51e6c44dbfcea2d&chksm=e8c4a143dfb328555c5aa2108860efdcbde2d935ace380e7f4240aa1fcae27dc42e7db9b71a0&scene=21#wechat_redirect" target="_blank" data-itemshowtype="0" data-linktype="2">如何排查Java内存泄漏？看完我给跪了！</a> 上篇好文： <a href="http://mp.weixin.qq.com/s?__biz=MzIzNzYxNDYzNw==&mid=2247483940&idx=1&sn=9584d7e837bcbe3be99a483cffbe36a3&chksm=e8c4a166dfb328706a637defc33442bb82dd9c112debfa0520721bf9b78c5ddaeef58bbda924&scene=21#wechat_redirect" target="_blank" data-itemshowtype="0" data-linktype="2">Java动态规划</a> <hr style="border-style: solid;border-width: 1px 0 0;border-color: rgba(0,0,0,0.1);-webkit-transform-origin: 0 0;-webkit-transform: scale(1, 0.5);transform-origin: 0 0;transform: scale(1, 0.5);"> 文章对你是否有帮助呢？ 别忘记点右上角按钮分享给更多人哦<img src="/upload/bdebeb96d99dba4b9471ab46678229a3.null" data-ratio="1" data-w="20" style="display:inline-block;width:20px;vertical-align:text-bottom;">~ <hr style="border-style: solid;border-width: 1px 0 0;border-color: rgba(0,0,0,0.1);-webkit-transform-origin: 0 0;-webkit-transform: scale(1, 0.5);transform-origin: 0 0;transform: scale(1, 0.5);"> <img class="rich_pages" data-backh="559" data-backw="556" data-before-oversubscription-url="https://mmbiz.qlogo.cn/mmbiz_png/6tgwFZrjh8GibDI59ziaoehN9TZWkByCg6opsiavxSyuKMRyTwibeIHnpvoa449EicdzwR1bXljia0pKDmIeqZL78s3A/0?wx_fmt=png" data-ratio="1.0055096418732783" data-s="300,640" src="/upload/7f46187a9ace7587f6cde759c3b3e2da.png" data-type="png" data-w="726" style="width: 556px;"> <hr style="white-space: normal;border-style: solid;border-right-width: 0px;border-bottom-width: 0px;border-left-width: 0px;border-color: rgba(0, 0, 0, 0.1);transform-origin: 0px 0px;transform: scale(1, 0.5);"> 点击在看，和我一起帮助更多开发者！

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<img class="" data-ratio="0.6666666666666666" data-type="png" data-w="127" src="/upload/4c8b91599182ea5ba1ead110e9271956.png" style="vertical-align: bottom;width:auto !important;max-width:100% !important;height:auto !important;"> 还没关注？伸出中指点这里！ 本文作者：原子弹大侠 狸猫技术窝特约作者，阿里P8高级技术专家 <section class="KolEditor" data-tools-id="85858" style="white-space: normal;"> <section class="Powered-by-KolEditor V5" powered-by="KolEditor.us"> <section class=""> <section class="" style="margin-bottom: 5px;height: 5px;background-color: rgb(154, 157, 170);"></section> <section class="" style="margin-bottom: 5px;height: 5px;background-color: rgb(154, 157, 170);"></section> <section class="" style="margin-bottom: 5px;height: 5px;background-color: rgb(154, 157, 170);"></section> <section class="" style="margin-bottom: 5px;height: 5px;background-color: rgb(154, 157, 170);"></section> <section class="" style="margin-bottom: 5px;height: 5px;background-color: rgb(154, 157, 170);"></section> <section class="" style="margin-bottom: 5px;height: 5px;background-color: rgb(154, 157, 170);"></section> <section class="" style="margin-top: -40px;margin-right: 1.5em;margin-left: 1.5em;padding: 10px;background-color: rgb(226, 230, 0);"> <section class="Powered-by-KolEditor V5" powered-by="KolEditor.us"> <section class=""> <section class="" style="text-align: center;color: rgb(255, 255, 255);"> <section> 聊技术、论职场！ </section> <section> 为IT人打造一个“有温度”的狸猫技术窝 </section> </section> </section> </section> </section> </section> </section> </section> 转载请联系【狸猫技术窝】获取授权 概述 很多人想要到阿里巴巴、美团、京东等互联网大公司去面试，但是现在互联网大厂面试一般都必定会考核JVM相关的知识积累和实践经验，毕竟线上系统写好代码部署之后，每个工程师都必须关注JVM相关的东西，比如OOM、GC等问题. 所以一起来看看JVM的最基本的区域划分以及工作原理，这个基本上是互联网公司面试必问。 区域划分 jvm的区域划分如下所示： <img class="inline-img" data-ratio="0.3758741258741259" data-type="png" src="/upload/a9677d786e8401fa7bdd7dc3b9a117c3.png" data-w="572"> 大致就是分为：程序计数器，虚拟机栈，堆，方法区，本地方法栈，这几个部分。 接下来我们从自己写好的Java代码如何通过JVM来运行的角度，来分析一下JVM里这些区域是如何支撑我们的Java代码跑起来的。 程序计数器 假设我们有如下的一个类，就是最最基本的一个HelloWorld而已： public class HelloWorld {         public static void main(String[] args) {             System.out.println("Hello World");         } } 上面那段代码首先会存在于 “.java” 后缀的文件里，这个文件就是java源代码文件，但是这个文件是面向我们程序员的，计算机他是看不懂你写的这段代码的 所以此时就得通过编译器，把“.java”后缀的源代码文件编译为“.class”后缀的字节码文件。 这个“.class”后缀的字节码文件里，存放的就是对你写出来的代码编译好的字节码了，这个字节码才是计算器可以理解的一种语言，而不是我们写出来的那一堆代码。 这个字节码看起来大概是下面这样的： <img class="rich_pages" data-copyright="0" data-ratio="0.6419098143236074" data-s="300,640" src="/upload/eafa24b0eef5a0d4adb097630015acba.png" data-type="png" data-w="377" style=""> 这段字节码并不是完全对照着HelloWorld那个类来写的，就是给一段示例，让大家知道“.java”翻译成的“.class”是大概什么样子的。 这里比如说“0: aload_0”这样的，就是“字节码指令”，他对应了一条一条的机器指令，计算机只有读到这种机器码指令，才知道具体应该要干什么。 比如说字节码指令可能会让计算机从内存里读取某个数据，或者把某个数据写入到内存里去，都有可能，各种各样的指令，就会指示计算机去干各种各样的事情。 所以现在首先明白一点，我们写好的Java代码是会被翻译成字节码的，对应各种字节码指令。 那么Java代码通过JVM跑起来的第一件事情就明确了，首先Java代码被编译出来的字节码指令一定会被一条一条的执行，这样才能实现我们写好的代码被执行的效果。 那么在执行字节码指令的时候，JVM里的程序计数器就是用来记录每个线程当前执行的字节码指令的位置的，记录当前线程目前执行到了哪一条字节码指令。 因为会有多个线程来并发的执行各种不同的代码，所以每个线程都有自己的一个程序计数器，专门记录当前这个线程目前执行到了哪一条字节码指令了 下图更加清晰的展示出了他们之间的关系。 <img class="inline-img" data-ratio="0.7082066869300911" data-type="png" src="/upload/a633ffe745628df23f84418e86f5d82f.png" data-w="329"> Java虚拟机栈 Java代码在执行的时候，一定是线程来执行某个方法中的代码，比如哪怕就是上面的那个最基础的HelloWorld代码，也会有一个main线程来执行main方法里的代码。 在方法里，经常会定义一些方法内的局部变量，比如下面这样，就在方法里定义了一个局部变量“name”。 public void sayHello() {         String name = "hello"; } 所以JVM必须有一块区域是来保存每个方法内的局部变量等等数据的，这个区域就是Java虚拟机栈 每个线程都会去执行各种方法的代码，方法内还会嵌套调用其他的方法，所以首先每个线程都有自己的Java虚拟机栈。 如果线程执行了一个方法，那么就会被这个方法调用创建对应的一个栈帧，栈帧里就有这个方法的局部变量表、操作数栈、动态链接、方法出口等东西，但是这里别的不太好理解，先理解一个局部变量就可以。 比如说一个线程调用了上面写的“sayHello”方法，那么就会为“sayHello”方法创建一个栈帧，压入线程自己的Java虚拟机栈里面去。 在栈帧的局部变量表里就会有“name”这个局部变量，下图展示了这个过程。 <img class="inline-img" data-ratio="2.2457142857142856" data-type="png" src="/upload/2da1ad0c40c82a9a529f184b8a82598b.png" style="width: 50%;height: auto;" data-w="175"> 接着如果“sayHello”方法调用了另外一个“greeting”方法，比如下面那样的代码： <img class="rich_pages" data-copyright="0" data-ratio="0.6707920792079208" data-s="300,640" src="/upload/f9ae08bc3d0e143ce332e2a68859aeec.png" data-type="png" data-w="404" style=""> 那么这个时候会给“greeting”方法又创建一个栈帧压入线程的Java虚拟机栈里，因为开始执行“greeting”方法了，而且“greeting”方法的栈帧的局部变量表里会有一个“greet”变量，这是“greeting”方法的局部变量。 <img class="inline-img" data-ratio="2.2457142857142856" data-type="png" src="/upload/32b9ef2d37558ba0019ad39b852f40d.png" style="width: 50%;height: auto;" data-w="175"> 接着如果“greeting”方法执行完毕了，就会把“greeting”方法对应的栈帧从Java虚拟机栈里给出栈，然后如果“sayHello”方法也执行完毕了，就会把“sayHello”方法也从Java虚拟机栈里出栈。 这就是JVM中的 “ Java虚拟机栈 ” 这个组件的作用，调用执行任何方法的时候，都会给方法创建栈帧然后入栈。 而在栈帧里存放了这个方法对应的局部变量之类的数据，包括这个方法执行的其他相关的信息，方法执行完毕之后就出栈。 Java堆内存 JVM中有另外一个非常关键的区域，就是Java堆，这里就是存放我们在代码中创建的各种对象的，比如说下面的代码： public void teach(String name) {     Student student = new Student(name);     student.study(); } 上面的 “new Student(name)” 这个代码就是创建了一个Student类型的对象实例，这个对象实例里面会包含一些数据。 比如说这个Student的“name”就是属于这个对象实例的一个数据，那么类似Student这样的对象，就会存放在Java堆内存里。 Java堆内存区域里会放入类似Student的对象，然后方法的栈帧的局部变量表里，这个引用类型的“student”局部变量就会存放Student对象的地址。 相当于你可以认为局部变量表里的“student”指向了Java堆里的Student对象。 看下图会更加清晰一些。 <img class="inline-img" data-ratio="0.6169544740973313" data-type="png" src="/upload/90beb47c8f92960aafecbcf577bd2e32.png" data-w="637"> 方法区 / Metaspace 这个方法区是在JDK 1.8以前的版本里，代表JVM中的一块区域，主要是放类似Student类自己的信息的，平时用到的各种类的信息，都是放在这个区域里的，还会有一些类似常量池的东西放在这个区域里。 但是在JDK 1.8以后，这块区域的名字改了，叫做“Metaspace”，可以认为是“元数据空间”这样的意思，这里当然主要其实还是存放我们自己写的各种类相关的信息。 本地方法栈 其实在JDK很多底层API里，比如IO相关的，NIO相关的，网络Socket相关的，如果大家去看他内部的源码，会发现很多地方都不是Java代码了。 很多地方都会去走native方法，去调用本地操作系统里面的一些方法，可能调用的都是c语言写的方法，或者一些底层类库，比如下面这样的： public native int hashCode(); 在调用这种native方法的时候，就会有线程对应的本地方法栈，这个里面也是跟Java虚拟机栈类似的，也是存放各种native方法的局部变量表之类的信息。 堆外内存 还有一个区域，是不属于JVM的，通过NIO中的allocateDirect这种API，可以在Java堆外分配内存空间。 然后通过Java虚拟机里的 DirectByteBuffer 来引用和操作堆外内存空间，其实很多技术都会用这种方式，因为有一些场景下，堆外内存分配可以提升性能。 总结 最后做一点总结，我们的Java代码通过JVM来运行的时候，首先一定会一行一行执行编译好的字节码指令。 然后在执行的过程中，对于方法的调用，会通过Java虚拟机栈来为每个方法创建栈帧入栈和出栈，而且栈帧里有方法的局部变量表 接着对于对象的创建，会分配到Java堆内存里去 对于类信息的存储，会放在方法区 / Metaspace这样的区域里。 另外有两块特殊的区域： <ul class=" list-paddingleft-2" style="list-style-type: disc;"> <li>本地方法栈，是执行native方法时候用的栈，跟Java虚拟机栈是类似的</li> <li>堆外内存，是可以在Java堆外分配内存空间来存储一些对象。</li> </ul> END <section class="KolEditor" style="white-space: normal;"> <section style="margin: 10px;padding: 17px 10px 15px 16px;border-width: 1px;border-style: solid;border-color: rgb(246, 73, 13);display: flex;align-items: center;justify-content: center;flex-direction: column;"> <section style="padding-bottom: 5px;display: flex;align-items: center;justify-content: flex-start;border-bottom: 4px solid rgb(246, 73, 13);width: 508px;align-self: flex-start;">  作者简介：  </section> <section style="margin-top: 13px;padding-right: 10px;padding-left: 10px;"> 原子弹大侠，阿里P8高级技术专家 经历过每日百亿流量的互联网系统架构，尤其对上亿用户场景下的高并发系统架构设计以及性能优化相关领域有深入的研究。 </section> </section> </section> 扫描二维码，即刻关注【狸猫技术窝】 阿里、京东、美团、字节跳动 顶尖技术专家坐镇 为IT人打造一个 “有温度” 的技术窝！ <section class="KolEditor" data-tools-id="69164" style="white-space: normal;"> <section style="margin-top: 20px;"> <section style="margin-right: auto;margin-left: auto;background-image: url(https://mmbiz.qpic.cn/mmbiz_gif/vnOqylzBGCSwjFsfNvrwxsRkgjr6jVfOHXUSyNIpYXY62BsG3zqZ8S3VEgqu9Ulib1Tdvqibcic8kag4XoVoygzew/640?wx_fmt=gif);background-repeat: no-repeat;width: 240px;background-size: 100%;text-align: center;"> <section class="" style="margin-right: auto;margin-left: auto;padding-top: 8px;padding-bottom: 20px;padding-left: 90px;width: 210px;"> <img class="" data-copyright="0" data-cropselx1="0" data-cropselx2="120" data-cropsely1="0" data-cropsely2="120" data-ratio="0.6666666666666666" data-type="jpeg" data-w="258" src="/upload/578288c965b89f74b583291d3fc98c86.jpg" style="height: 120px;width: 120px;"> </section> </section> </section> </section>

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