|
|
<!doctypehtml><html lang=zh-CN><meta charset=UTF-8><meta content=width=device-width name=viewport><meta content=#222 name=theme-color><meta content="Hexo 7.1.0" name=generator><link href=https://cdnjs.cloudflare.com rel=preconnect><link href=/images/apple-touch-icon-next.png rel=apple-touch-icon sizes=180x180><link href=/images/favicon-32x32-next.png rel=icon sizes=32x32 type=image/png><link href=/images/favicon-16x16-next.png rel=icon sizes=16x16 type=image/png><link color=#222 href=/images/logo.svg rel=mask-icon><meta content=2X6S9P7CAjXjVvw8YyQR8pCu-B0oEu7O9quLgxXuWyA name=google-site-verification><meta content=dV8JGNzi0c name=baidu-site-verification><script>!function(){var t=!1;function e(){var e;t||(t=!0,(e=document.createElement("script")).setAttribute("data-ad-client","ca-pub-7480618470784058"),e.async=!0,e.src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js",document.head.appendChild(e))}function a(){"requestIdleCallback"in window?window.requestIdleCallback(e,{timeout:5e3}):window.setTimeout(e,5e3)}"complete"===document.readyState?a():window.addEventListener("load",a,{once:!0})}()</script><link href=/css/main.css rel=stylesheet><link crossorigin=anonymous href=https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.0/css/all.min.css integrity=sha256-yIDrPSXHZdOZhAqiBP7CKzIwMQmRCJ8UeB8Jo17YC4o= rel=stylesheet><link crossorigin=anonymous href=https://cdnjs.cloudflare.com/ajax/libs/fancyapps-ui/5.0.28/fancybox/fancybox.css integrity=sha256-6cQIC71/iBIYXFK+0RHAvwmjwWzkWd+r7v/BX3/vZDc= rel=stylesheet><script class=next-config data-name=main type=application/json>{"hostname":"nicksxs.me","root":"/","images":"/images","scheme":"Pisces","darkmode":false,"version":"8.19.1","exturl":false,"sidebar":{"position":"left","display":"post","padding":18,"offset":12},"copycode":{"enable":true,"style":"default"},"fold":{"enable":false,"height":500},"bookmark":{"enable":false,"color":"#222","save":"auto"},"mediumzoom":false,"lazyload":true,"pangu":false,"comments":{"style":"tabs","active":null,"storage":true,"lazyload":true,"nav":null},"stickytabs":false,"motion":{"enable":false,"async":false,"transition":{"menu_item":"fadeInDown","post_block":"fadeIn","post_header":"fadeInDown","post_body":"fadeInDown","coll_header":"fadeInLeft","sidebar":"fadeInUp"}},"prism":false,"i18n":{"placeholder":"搜索...","empty":"没有找到任何搜索结果:${query}","hits_time":"找到 ${hits} 个搜索结果(用时 ${time} 毫秒)","hits":"找到 ${hits} 个搜索结果"},"algolia":{"appID":"663Q99OQQD","apiKey":"e461a1371d12cec1491c1153b288a9ed","indexName":"nicksxs","hits":{"per_page":10}}}</script><script src=/js/config.js></script><meta content="Java 真的是任何一个中间件,比较常用的那种,都有很多内容值得深挖,比如这个缓存,慢慢有过一些感悟,比如如何提升性能,缓存无疑是一大重要手段,最底层开始 CPU 就有缓存,而且又小又贵,再往上一点内存一般作为硬盘存储在运行时的存储,一般在代码里也会用内存作为一些本地缓存,譬如…" name=description><meta content=article property=og:type><meta content="mybatis 的缓存是怎么回事" property=og:title><meta content=https://nicksxs.me/2020/10/03/mybatis-%E7%9A%84%E7%BC%93%E5%AD%98%E6%98%AF%E6%80%8E%E4%B9%88%E5%9B%9E%E4%BA%8B/index.html property=og:url><meta content="Nicksxs's Blog" property=og:site_name><meta content="Java 真的是任何一个中间件,比较常用的那种,都有很多内容值得深挖,比如这个缓存,慢慢有过一些感悟,比如如何提升性能,缓存无疑是一大重要手段,最底层开始 CPU 就有缓存,而且又小又贵,再往上一点内存一般作为硬盘存储在运行时的存储,一般在代码里也会用内存作为一些本地缓存,譬如…" property=og:description><meta content=zh_CN property=og:locale><meta content=2020-10-03T14:43:13.000Z property=article:published_time><meta content=2020-10-03T14:43:13.000Z property=article:modified_time><meta content=Nicksxs property=article:author><meta content=Java property=article:tag><meta content=MySQL property=article:tag><meta content=Mybatis property=article:tag><meta content=缓存 property=article:tag><meta content=summary name=twitter:card><link href=https://nicksxs.me/2020/10/03/mybatis-%E7%9A%84%E7%BC%93%E5%AD%98%E6%98%AF%E6%80%8E%E4%B9%88%E5%9B%9E%E4%BA%8B/ rel=canonical><script class=next-config data-name=page type=application/json>{"sidebar":"","isHome":false,"isPost":true,"lang":"zh-CN","comments":true,"permalink":"https://nicksxs.me/2020/10/03/mybatis-%E7%9A%84%E7%BC%93%E5%AD%98%E6%98%AF%E6%80%8E%E4%B9%88%E5%9B%9E%E4%BA%8B/","path":"2020/10/03/mybatis-的缓存是怎么回事/","title":"mybatis 的缓存是怎么回事"}</script><script class=next-config data-name=calendar type=application/json>""</script><title>mybatis 的缓存是怎么回事 | Nicksxs's Blog</title><script src=/js/third-party/analytics/baidu-analytics.js></script><script async src=https://hm.baidu.com/hm.js?20f33b3c0c0eff9b1522999c0015646d></script><noscript><link href=/css/noscript.css rel=stylesheet></noscript><link title="Nicksxs's Blog" href=/atom.xml rel=alternate type=application/atom+xml><body itemscope itemtype=http://schema.org/WebPage><div class=headband></div><main class=main><div class=column><header class=header itemscope itemtype=http://schema.org/WPHeader><div class=site-brand-container><div class=site-nav-toggle><div aria-label=切换导航栏 class=toggle role=button><span class=toggle-line></span><span class=toggle-line></span><span class=toggle-line></span></div></div><div class=site-meta><a class=brand href=/ rel=start><i class=logo-line></i><p class=site-title>Nicksxs's Blog</p><i class=logo-line></i></a><p class=site-subtitle itemprop=description>What hurts more, the pain of hard work or the pain of regret?</div><div class=site-nav-right><div class="toggle popup-trigger" aria-label=搜索 role=button><i class="fa fa-search fa-fw fa-lg"></i></div></div></div><nav class=site-nav><ul class="main-menu menu"><li class="menu-item menu-item-home"><a href=/ rel=section><i class="fa fa-home fa-fw"></i>首页</a><li class="menu-item menu-item-about"><a href=/about/ rel=section><i class="fa fa-user fa-fw"></i>关于我</a><li class="menu-item menu-item-mirror"><a href=https://nicksxs.com/ rel=section target=_blank><i class="fa fa-user fa-fw"></i>国内镜像</a><li class="menu-item menu-item-tags"><a href=/tags/ rel=section><i class="fa fa-tags fa-fw"></i>标签</a><li class="menu-item menu-item-categories"><a href=/categories/ rel=section><i class="fa fa-th fa-fw"></i>分类</a><li class="menu-item menu-item-archives"><a href=/archives/ rel=section><i class="fa fa-archive fa-fw"></i>归档</a><li class="menu-item menu-item-top"><a href=/top/ rel=section><i class="fa fa-th fa-fw"></i>热度</a><li class="menu-item menu-item-sitemap"><a href=/sitemap.xml rel=section><i class="fa fa-sitemap fa-fw"></i>站点地图</a><li class="menu-item menu-item-commonweal"><a href=/404/ rel=section><i class="fa fa-heartbeat fa-fw"></i>公益 404</a><li class="menu-item menu-item-search"><a class=popup-trigger role=button><i class="fa fa-search fa-fw"></i>搜索</a></ul></nav><div class=search-pop-overlay><div class="popup search-popup"><div class=search-header><span class=search-icon><i class="fa fa-search"></i></span><div class=search-input-container></div><span class=popup-btn-close role=button><i class="fa fa-times-circle"></i></span></div><div class=search-result-container><div class=algolia-stats><hr></div><div class=algolia-hits></div><div class=algolia-pagination></div></div></div></div></header><aside class=sidebar><div class="sidebar-inner sidebar-nav-active sidebar-toc-active"><ul class=sidebar-nav><li class=sidebar-nav-toc>文章目录<li class=sidebar-nav-overview>站点概览</ul><div class=sidebar-panel-container><div class="post-toc-wrap sidebar-panel"><div class="post-toc animated"><ol class=nav><li class="nav-item nav-level-3"><a class=nav-link href=#%E4%B8%80%E7%BA%A7%E7%BC%93%E5%AD%98><span class=nav-number>1.</span> <span class=nav-text>一级缓存</span></a><li class="nav-item nav-level-3"><a class=nav-link href=#%E4%BA%8C%E7%BA%A7%E7%BC%93%E5%AD%98><span class=nav-number>2.</span> <span class=nav-text>二级缓存</span></a></ol></div></div><div class="site-overview-wrap sidebar-panel"><div class="site-author animated" itemprop=author itemscope itemtype=http://schema.org/Person><img alt=Nicksxs class=site-author-image itemprop=image src=/uploads/avatar.jpg><p class=site-author-name itemprop=name>Nicksxs<div class=site-description itemprop=description>Nicksxs 的技术博客,专注 Java、JVM、分布式系统、数据库与大模型工程实践</div></div><div class="site-state-wrap animated"><nav class=site-state><div class="site-state-item site-state-posts"><a href=/archives/><span class=site-state-item-count>386</span> <span class=site-state-item-name>日志</span></a></div><div class="site-state-item site-state-categories"><a href=/categories/><span class=site-state-item-count>179</span> <span class=site-state-item-name>分类</span></a></div><div class="site-state-item site-state-tags"><a href=/tags/><span class=site-state-item-count>325</span> <span class=site-state-item-name>标签</span></a></div></nav></div><div class="links-of-author animated"><span class=links-of-author-item><a rel="noopener me" title="GitHub → https://github.com/nicksxs" href=https://github.com/nicksxs target=_blank><i class="fab fa-github fa-fw"></i>GitHub</a> </span><span class=links-of-author-item><a rel="noopener me" title="E-Mail → mailto:nicksxs1202@gmail.com" href=mailto:nicksxs1202@gmail.com target=_blank><i class="fa fa-envelope fa-fw"></i>E-Mail</a></span></div><div class="cc-license animated" itemprop=license><a class=cc-opacity href=https://creativecommons.org/licenses/by-nc-sa/4.0/ rel=noopener target=_blank><img alt="Creative Commons" src=https://cdnjs.cloudflare.com/ajax/libs/creativecommons-vocabulary/2020.11.3/assets/license_badges/small/by_nc_sa.svg></a></div><div class="widget-wrap sidebar-tag-cloud"><div class=tag-cloud-tags><a class=tag-cloud-10 href=/tags/Java/ style=font-size:16px>Java</a><a class=tag-cloud-9 href=/tags/leetcode/ style=font-size:15.64px>leetcode</a><a class=tag-cloud-9 href=/tags/%E7%94%9F%E6%B4%BB/ style=font-size:15.29px>生活</a><a class=tag-cloud-8 href=/tags/LLM/ style=font-size:14.93px>LLM</a><a class=tag-cloud-7 href=/tags/%E9%A2%98%E8%A7%A3/ style=font-size:14.57px>题解</a><a class=tag-cloud-6 href=/tags/SpringBoot/ style=font-size:14.21px>SpringBoot</a><a class=tag-cloud-6 href=/tags/MySQL/ style=font-size:14.21px>MySQL</a><a class=tag-cloud-6 href=/tags/C/ style=font-size:13.86px>C++</a><a class=tag-cloud-5 href=/tags/Redis/ style=font-size:13.5px>Redis</a><a class=tag-cloud-4 href=/tags/Tomcat/ style=font-size:13.14px>Tomcat</a><a class=tag-cloud-4 href=/tags/Mybatis/ style=font-size:13.14px>Mybatis</a><a class=tag-cloud-4 href=/tags/%E5%B0%8F%E6%8A%80%E5%B7%A7/ style=font-size:12.79px>小技巧</a><a class=tag-cloud-3 href=/tags/%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84/ style=font-size:12.43px>数据结构</a><a class=tag-cloud-3 href=/tags/%E6%BA%90%E7%A0%81/ style=font-size:12.43px>源码</a><a class=tag-cloud-2 href=/tags/MQ/ style=font-size:12.07px>MQ</a><a class=tag-cloud-2 href=/tags/%E6%B6%88%E6%81%AF%E9%98%9F%E5%88%97/ style=font-size:12.07px>消息队列</a><a class=tag-cloud-2 href=/tags/RocketMQ/ style=font-size:12.07px>RocketMQ</a><a class=tag-cloud-2 href=/tags/%E8%BF%90%E5%8A%A8/ style=font-size:12.07px>运动</a><a class=tag-cloud-1 href=/tags/php/ style=font-size:11.71px>php</a><a class=tag-cloud-1 href=/tags/Spring/ style=font-size:11.36px>Spring</a><a class=tag-cloud-1 href=/tags/linux/ style=font-size:11.36px>linux</a><a class=tag-cloud-1 href=/tags/%E5%87%8F%E8%82%A5/ style=font-size:11.36px>减肥</a><a class=tag-cloud-1 href=/tags/%E8%B7%91%E6%AD%A5/ style=font-size:11.36px>跑步</a><a class=tag-cloud-0 href=/tags/Dubbo/ style=font-size:11px>Dubbo</a></div></div><div class="affiliate-creative affiliate-creative--sidebar" data-affiliate-id=tencent-cloud-general><a rel="sponsored noopener" aria-label=腾讯云产品优惠 href=https://cloud.tencent.com/act/cps/redirect?redirect=2446&cps_key=2e33a1eedb380997d03618b4a5ba6ca7&from=console target=_blank><img alt=腾讯云服务器、数据库和云产品优惠 decoding=async height=419 loading=lazy src=/uploads/affiliate/tencent-cloud-general.webp width=690> </a><span class=affiliate-disclosure>推广</span></div></div></div></div><div class="sidebar-inner sidebar-blogroll"><div class="links-of-blogroll animated"><div class=links-of-blogroll-title><i class="fa fa-globe fa-fw"></i> 链接</div><ul class=links-of-blogroll-list><li class=links-of-blogroll-item><a href=https://covermusic.cn/ rel=noopener target=_blank title=https://covermusic.cn>69伙伴</a></ul></div></div></aside></div><div class="main-inner post posts-expand"><div class=post-block><article class=post-content itemscope itemtype=http://schema.org/Article lang=zh-CN><link href=https://nicksxs.me/2020/10/03/mybatis-%E7%9A%84%E7%BC%93%E5%AD%98%E6%98%AF%E6%80%8E%E4%B9%88%E5%9B%9E%E4%BA%8B/ itemprop=mainEntityOfPage><span hidden itemprop=author itemscope itemtype=http://schema.org/Person><meta content=/uploads/avatar.jpg itemprop=image><meta content=Nicksxs itemprop=name></span><span hidden itemprop=publisher itemscope itemtype=http://schema.org/Organization><meta content="Nicksxs's Blog" itemprop=name><meta content="Nicksxs 的技术博客,专注 Java、JVM、分布式系统、数据库与大模型工程实践" itemprop=description></span><span hidden itemprop=post itemscope itemtype=http://schema.org/CreativeWork><meta content="mybatis 的缓存是怎么回事 | Nicksxs's Blog" itemprop=name><meta content="Java 真的是任何一个中间件,比较常用的那种,都有很多内容值得深挖,比如这个缓存,慢慢有过一些感悟,比如如何提升性能,缓存无疑是一大重要手段,最底层开始 CPU 就有缓存,而且又小又贵,再往上一点内存一般作为硬盘存储在运行时的存储,一般在代码里也会用内存作为一些本地缓存,譬如…" itemprop=description></span><header class=post-header><h1 itemprop="name headline" class=post-title>mybatis 的缓存是怎么回事</h1><div class=post-meta-container><div class=post-meta><span class=post-meta-item><span class=post-meta-item-icon><i class="far fa-calendar"></i> </span><span class=post-meta-item-text>发表于</span> <time itemprop="dateCreated datePublished" title="创建时间:2020-10-03 22:43:13" datetime=2020-10-03T22:43:13+08:00>2020-10-03</time> </span><span class=post-meta-item><span class=post-meta-item-icon><i class="far fa-folder"></i> </span><span class=post-meta-item-text>分类于</span> <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Java/ itemprop=url rel=index><span itemprop=name>Java</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Java/Mybatis/ itemprop=url rel=index><span itemprop=name>Mybatis</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Mybatis/ itemprop=url rel=index><span itemprop=name>Mybatis</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Spring/ itemprop=url rel=index><span itemprop=name>Spring</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Mybatis/%E7%BC%93%E5%AD%98/ itemprop=url rel=index><span itemprop=name>缓存</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Spring/Mybatis/ itemprop=url rel=index><span itemprop=name>Mybatis</span></a> </span></span><span class="post-meta-item cloudflare-page-counter" data-title="mybatis 的缓存是怎么回事" data-increment=true data-path=/2020/10/03/mybatis-%E7%9A%84%E7%BC%93%E5%AD%98%E6%98%AF%E6%80%8E%E4%B9%88%E5%9B%9E%E4%BA%8B/ title=阅读次数><span class=post-meta-item-icon><i class="far fa-eye"></i> </span><span class=post-meta-item-text>阅读次数:</span> <span class=cloudflare-page-counter-count></span></span></div><div class=post-description>Java 真的是任何一个中间件,比较常用的那种,都有很多内容值得深挖,比如这个缓存,慢慢有过一些感悟,比如如何提升性能,缓存无疑是一大重要手段,最底层开始 CPU 就有缓存,而且又小又贵,再往上一点内存一般作为硬盘存储在运行时的存储,一般在代码里也会用内存作为一些本地缓存,譬如…</div></div></header><div class=post-body itemprop=articleBody><p>Java 真的是任何一个中间件,比较常用的那种,都有很多内容值得深挖,比如这个缓存,慢慢有过一些感悟,比如如何提升性能,缓存无疑是一大重要手段,最底层开始 CPU 就有缓存,而且又小又贵,再往上一点内存一般作为硬盘存储在运行时的存储,一般在代码里也会用内存作为一些本地缓存,譬如数据库,像 mysql 这种也是有innodb_buffer_pool来提升查询效率,本质上理解就是用更快的存储作为相对慢存储的缓存,减少查询直接访问较慢的存储,并且这个都是相对的,比起 cpu 的缓存,那内存也是渣,但是与普通机械硬盘相比,那也是两个次元的水平。<p>闲扯这么多来说说 mybatis 的缓存,mybatis 一般作为一个轻量级的 orm 使用,相对应的就是比较重量级的 hibernate,不过不在这次讨论范围,上一次是主要讲了 mybatis 在解析 sql 过程中,对于两种占位符的不同替换实现策略,这次主要聊下 mybatis 的缓存,前面其实得了解下前置的东西,比如 sqlsession,先当做我们知道 sqlsession 是个什么玩意,可能或多或少的知道 mybatis 是有两级缓存,<h3 id=一级缓存><a class=headerlink href=#一级缓存 title=一级缓存></a>一级缓存</h3><p>第一级的缓存是在 <a href=https://github.com/mybatis/mybatis-3/blob/master/src/main/java/org/apache/ibatis/executor/BaseExecutor.java#L65 rel=noopener target=_blank>BaseExecutor</a> 中的 <a href=https://github.com/mybatis/mybatis-3/blob/master/src/main/java/org/apache/ibatis/cache/impl/PerpetualCache.java#L27 rel=noopener target=_blank>PerpetualCache</a>,它是个最基本的缓存实现类,使用了 HashMap 实现缓存功能,代码其实没几十行<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br><span class=line>57</span><br><span class=line>58</span><br><span class=line>59</span><br><span class=line>60</span><br><span class=line>61</span><br><span class=line>62</span><br><span class=line>63</span><br><span class=line>64</span><br><span class=line>65</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>class</span> <span class="title class_">PerpetualCache</span> <span class=keyword>implements</span> <span class="title class_">Cache</span> {</span><br><span class=line></span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> String id;</span><br><span class=line></span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> Map<Object, Object> cache = <span class=keyword>new</span> <span class="title class_">HashMap</span><>();</span><br><span class=line></span><br><span class=line> <span class=keyword>public</span> <span class="title function_">PerpetualCache</span><span class=params>(String id)</span> {</span><br><span class=line> <span class=built_in>this</span>.id = id;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> String <span class="title function_">getId</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>return</span> id;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=type>int</span> <span class="title function_">getSize</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>return</span> cache.size();</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">putObject</span><span class=params>(Object key, Object value)</span> {</span><br><span class=line> cache.put(key, value);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> Object <span class="title function_">getObject</span><span class=params>(Object key)</span> {</span><br><span class=line> <span class=keyword>return</span> cache.get(key);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> Object <span class="title function_">removeObject</span><span class=params>(Object key)</span> {</span><br><span class=line> <span class=keyword>return</span> cache.remove(key);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">clear</span><span class=params>()</span> {</span><br><span class=line> cache.clear();</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=type>boolean</span> <span class="title function_">equals</span><span class=params>(Object o)</span> {</span><br><span class=line> <span class=keyword>if</span> (getId() == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">CacheException</span>(<span class=string>"Cache instances require an ID."</span>);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (<span class=built_in>this</span> == o) {</span><br><span class=line> <span class=keyword>return</span> <span class=literal>true</span>;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (!(o <span class=keyword>instanceof</span> Cache)) {</span><br><span class=line> <span class=keyword>return</span> <span class=literal>false</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=type>Cache</span> <span class=variable>otherCache</span> <span class=operator>=</span> (Cache) o;</span><br><span class=line> <span class=keyword>return</span> getId().equals(otherCache.getId());</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <span class=type>int</span> <span class="title function_">hashCode</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>if</span> (getId() == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">CacheException</span>(<span class=string>"Cache instances require an ID."</span>);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> getId().hashCode();</span><br><span class=line> }</span><br><span class=line></span><br><span class=line>}</span><br></pre></table></figure><p>可以看一下BaseExecutor 的构造函数<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br></pre><td class=code><pre><span class=line><span class=keyword>protected</span> <span class="title function_">BaseExecutor</span><span class=params>(Configuration configuration, Transaction transaction)</span> {</span><br><span class=line> <span class=built_in>this</span>.transaction = transaction;</span><br><span class=line> <span class=built_in>this</span>.deferredLoads = <span class=keyword>new</span> <span class="title class_">ConcurrentLinkedQueue</span><>();</span><br><span class=line> <span class=built_in>this</span>.localCache = <span class=keyword>new</span> <span class="title class_">PerpetualCache</span>(<span class=string>"LocalCache"</span>);</span><br><span class=line> <span class=built_in>this</span>.localOutputParameterCache = <span class=keyword>new</span> <span class="title class_">PerpetualCache</span>(<span class=string>"LocalOutputParameterCache"</span>);</span><br><span class=line> <span class=built_in>this</span>.closed = <span class=literal>false</span>;</span><br><span class=line> <span class=built_in>this</span>.configuration = configuration;</span><br><span class=line> <span class=built_in>this</span>.wrapper = <span class=built_in>this</span>;</span><br><span class=line> }</span><br></pre></table></figure><p>就是把 PerpetualCache 作为 localCache,然后怎么使用我看简单看一下,BaseExecutor 的查询首先是调用这个函数<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <E> List<E> <span class="title function_">query</span><span class=params>(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>BoundSql</span> <span class=variable>boundSql</span> <span class=operator>=</span> ms.getBoundSql(parameter);</span><br><span class=line> <span class=type>CacheKey</span> <span class=variable>key</span> <span class=operator>=</span> createCacheKey(ms, parameter, rowBounds, boundSql);</span><br><span class=line> <span class=keyword>return</span> query(ms, parameter, rowBounds, resultHandler, key, boundSql);</span><br><span class=line> }</span><br></pre></table></figure><p>可以看到首先是调用了 <a href=https://github.com/mybatis/mybatis-3/blob/master/src/main/java/org/apache/ibatis/executor/BaseExecutor.java#L195 rel=noopener target=_blank>createCacheKey</a> 方法,这个方法呢,先不看怎么写的,如果我们自己要实现这么个缓存,首先这个缓存 key 的设计也是个问题,如果是以表名加主键作为 key,那么分页查询,或者没有主键的时候就不行,来看看 mybatis 是怎么设计的<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> CacheKey <span class="title function_">createCacheKey</span><span class=params>(MappedStatement ms, Object parameterObject, RowBounds rowBounds, BoundSql boundSql)</span> {</span><br><span class=line> <span class=keyword>if</span> (closed) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">ExecutorException</span>(<span class=string>"Executor was closed."</span>);</span><br><span class=line> }</span><br><span class=line> <span class=type>CacheKey</span> <span class=variable>cacheKey</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">CacheKey</span>();</span><br><span class=line> cacheKey.update(ms.getId());</span><br><span class=line> cacheKey.update(rowBounds.getOffset());</span><br><span class=line> cacheKey.update(rowBounds.getLimit());</span><br><span class=line> cacheKey.update(boundSql.getSql());</span><br><span class=line> List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();</span><br><span class=line> <span class=type>TypeHandlerRegistry</span> <span class=variable>typeHandlerRegistry</span> <span class=operator>=</span> ms.getConfiguration().getTypeHandlerRegistry();</span><br><span class=line> <span class=comment>// mimic DefaultParameterHandler logic</span></span><br><span class=line> <span class=keyword>for</span> (ParameterMapping parameterMapping : parameterMappings) {</span><br><span class=line> <span class=keyword>if</span> (parameterMapping.getMode() != ParameterMode.OUT) {</span><br><span class=line> Object value;</span><br><span class=line> <span class=type>String</span> <span class=variable>propertyName</span> <span class=operator>=</span> parameterMapping.getProperty();</span><br><span class=line> <span class=keyword>if</span> (boundSql.hasAdditionalParameter(propertyName)) {</span><br><span class=line> value = boundSql.getAdditionalParameter(propertyName);</span><br><span class=line> } <span class=keyword>else</span> <span class=keyword>if</span> (parameterObject == <span class=literal>null</span>) {</span><br><span class=line> value = <span class=literal>null</span>;</span><br><span class=line> } <span class=keyword>else</span> <span class=keyword>if</span> (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {</span><br><span class=line> value = parameterObject;</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=type>MetaObject</span> <span class=variable>metaObject</span> <span class=operator>=</span> configuration.newMetaObject(parameterObject);</span><br><span class=line> value = metaObject.getValue(propertyName);</span><br><span class=line> }</span><br><span class=line> cacheKey.update(value);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (configuration.getEnvironment() != <span class=literal>null</span>) {</span><br><span class=line> <span class=comment>// issue #176</span></span><br><span class=line> cacheKey.update(configuration.getEnvironment().getId());</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> cacheKey;</span><br><span class=line> }</span><br><span class=line></span><br></pre></table></figure><p>首先需要 id,这个 id 是 mapper 里方法的 id, 然后是偏移量跟返回行数,再就是 sql,然后是参数,基本上是会有影响的都加进去了,在这个 update 里面<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">update</span><span class=params>(Object object)</span> {</span><br><span class=line> <span class=type>int</span> <span class=variable>baseHashCode</span> <span class=operator>=</span> object == <span class=literal>null</span> ? <span class=number>1</span> : ArrayUtil.hashCode(object);</span><br><span class=line></span><br><span class=line> count++;</span><br><span class=line> checksum += baseHashCode;</span><br><span class=line> baseHashCode *= count;</span><br><span class=line></span><br><span class=line> hashcode = multiplier * hashcode + baseHashCode;</span><br><span class=line></span><br><span class=line> updateList.add(object);</span><br><span class=line> }</span><br></pre></table></figure><p>其实是一个 hash 转换,具体不纠结,就是提高特异性,然后回来就是继续调用 query<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <E> List<E> <span class="title function_">query</span><span class=params>(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> ErrorContext.instance().resource(ms.getResource()).activity(<span class=string>"executing a query"</span>).object(ms.getId());</span><br><span class=line> <span class=keyword>if</span> (closed) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">ExecutorException</span>(<span class=string>"Executor was closed."</span>);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (queryStack == <span class=number>0</span> && ms.isFlushCacheRequired()) {</span><br><span class=line> clearLocalCache();</span><br><span class=line> }</span><br><span class=line> List<E> list;</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> queryStack++;</span><br><span class=line> list = resultHandler == <span class=literal>null</span> ? (List<E>) localCache.getObject(key) : <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>if</span> (list != <span class=literal>null</span>) {</span><br><span class=line> handleLocallyCachedOutputParameters(ms, key, parameter, boundSql);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> list = queryFromDatabase(ms, parameter, rowBounds, resultHandler, key, boundSql);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>finally</span> {</span><br><span class=line> queryStack--;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (queryStack == <span class=number>0</span>) {</span><br><span class=line> <span class=keyword>for</span> (DeferredLoad deferredLoad : deferredLoads) {</span><br><span class=line> deferredLoad.load();</span><br><span class=line> }</span><br><span class=line> <span class=comment>// issue #601</span></span><br><span class=line> deferredLoads.clear();</span><br><span class=line> <span class=keyword>if</span> (configuration.getLocalCacheScope() == LocalCacheScope.STATEMENT) {</span><br><span class=line> <span class=comment>// issue #482</span></span><br><span class=line> clearLocalCache();</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> list;</span><br><span class=line> }</span><br></pre></table></figure><p>可以看到是先从 localCache 里取,取不到再 queryFromDatabase,其实比较简单,这是一级缓存,考虑到 sqlsession 跟 BaseExecutor 的关系,其实是随着 sqlsession 来保证这个缓存不会出现脏数据幻读的情况,当然事务相关的后面可能再单独聊。<h3 id=二级缓存><a class=headerlink href=#二级缓存 title=二级缓存></a>二级缓存</h3><p>其实这个一级二级顺序有点反过来,其实查询的是先走的二级缓存,当然二级的需要配置开启,默认不开,<br>需要通过<figure class="highlight xml"><table><tr><td class=gutter><pre><span class=line>1</span><br></pre><td class=code><pre><span class=line><span class=tag><<span class=name>setting</span> <span class=attr>name</span>=<span class=string>"cacheEnabled"</span> <span class=attr>value</span>=<span class=string>"true"</span>/></span></span><br></pre></table></figure><p>来开启,然后我们的查询就会走到<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>class</span> <span class="title class_">CachingExecutor</span> <span class=keyword>implements</span> <span class="title class_">Executor</span> {</span><br><span class=line></span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> Executor delegate;</span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> <span class=type>TransactionalCacheManager</span> <span class=variable>tcm</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">TransactionalCacheManager</span>();</span><br></pre></table></figure><p>这个 Executor 中,这里我放了类里面的元素,发现没有一个 Cache 类,这就是一个特点了,往下看查询过程<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <E> List<E> <span class="title function_">query</span><span class=params>(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>BoundSql</span> <span class=variable>boundSql</span> <span class=operator>=</span> ms.getBoundSql(parameterObject);</span><br><span class=line> <span class=type>CacheKey</span> <span class=variable>key</span> <span class=operator>=</span> createCacheKey(ms, parameterObject, rowBounds, boundSql);</span><br><span class=line> <span class=keyword>return</span> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <E> List<E> <span class="title function_">query</span><span class=params>(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)</span></span><br><span class=line> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>Cache</span> <span class=variable>cache</span> <span class=operator>=</span> ms.getCache();</span><br><span class=line> <span class=keyword>if</span> (cache != <span class=literal>null</span>) {</span><br><span class=line> flushCacheIfRequired(ms);</span><br><span class=line> <span class=keyword>if</span> (ms.isUseCache() && resultHandler == <span class=literal>null</span>) {</span><br><span class=line> ensureNoOutParams(ms, boundSql);</span><br><span class=line> <span class=meta>@SuppressWarnings("unchecked")</span></span><br><span class=line> List<E> list = (List<E>) tcm.getObject(cache, key);</span><br><span class=line> <span class=keyword>if</span> (list == <span class=literal>null</span>) {</span><br><span class=line> list = delegate.query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);</span><br><span class=line> tcm.putObject(cache, key, list); <span class=comment>// issue #578 and #116</span></span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> list;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> delegate.query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);</span><br><span class=line> }</span><br></pre></table></figure><p>看到没,其实缓存是从 tcm 这个成员变量里取,而这个是什么呢,事务性缓存(直译下),因为这个其实是用 MappedStatement 里的 Cache 作为key 从 tcm 的 map 取出来的<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>class</span> <span class="title class_">TransactionalCacheManager</span> {</span><br><span class=line></span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> Map<Cache, TransactionalCache> transactionalCaches = <span class=keyword>new</span> <span class="title class_">HashMap</span><>();</span><br></pre></table></figure><p>MappedStatement是被全局使用的,所以其实二级缓存是跟着 mapper 的 namespace 走的,可以被多个 CachingExecutor 获取到,就会出现线程安全问题,线程安全问题可以用SynchronizedCache来解决,就是加锁,但是对于事务中的脏读,使用了TransactionalCache来解决这个问题,<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>class</span> <span class="title class_">TransactionalCache</span> <span class=keyword>implements</span> <span class="title class_">Cache</span> {</span><br><span class=line></span><br><span class=line> <span class=keyword>private</span> <span class=keyword>static</span> <span class=keyword>final</span> <span class=type>Log</span> <span class=variable>log</span> <span class=operator>=</span> LogFactory.getLog(TransactionalCache.class);</span><br><span class=line></span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> Cache delegate;</span><br><span class=line> <span class=keyword>private</span> <span class=type>boolean</span> clearOnCommit;</span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> Map<Object, Object> entriesToAddOnCommit;</span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> Set<Object> entriesMissedInCache;</span><br></pre></table></figure><p>在事务还没提交的时候,会把中间状态的数据放在 entriesToAddOnCommit 中,只有在提交后会放进共享缓存中,<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">commit</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>if</span> (clearOnCommit) {</span><br><span class=line> delegate.clear();</span><br><span class=line> }</span><br><span class=line> flushPendingEntries();</span><br><span class=line> reset();</span><br><span class=line> }</span><br></pre></table></figure></div><footer class=post-footer><div class="affiliate-creative affiliate-creative--post-end" data-affiliate-id=tencent-cloud-general><a rel="sponsored noopener" aria-label=腾讯云产品优惠 href=https://cloud.tencent.com/act/cps/redirect?redirect=2446&cps_key=2e33a1eedb380997d03618b4a5ba6ca7&from=console target=_blank><img alt=腾讯云服务器、数据库和云产品优惠 decoding=async height=419 loading=lazy src=/uploads/affiliate/tencent-cloud-general.webp width=690> </a><span class=affiliate-disclosure>推广</span></div><div class=reward-container><div>请我一杯咖啡吧!</div><button>赞赏</button><div class=post-reward><div><img alt="Nicksxs 微信" src=https://i.loli.net/2020/01/12/NUlWanT31E8LQGx.png><span>微信</span></div><div><img alt="Nicksxs 支付宝" src=https://ooo.0o0.ooo/2016/08/17/57b421e773057.jpg><span>支付宝</span></div></div></div><div class=post-copyright><ul><li class=post-copyright-author><strong>本文作者: </strong>Nicksxs<li class=post-copyright-link><strong>本文链接:</strong> <a title="mybatis 的缓存是怎么回事" href=https://nicksxs.me/2020/10/03/mybatis-%E7%9A%84%E7%BC%93%E5%AD%98%E6%98%AF%E6%80%8E%E4%B9%88%E5%9B%9E%E4%BA%8B/>https://nicksxs.me/2020/10/03/mybatis-的缓存是怎么回事/</a><li class=post-copyright-license><strong>版权声明: </strong>本博客所有文章除特别声明外,均采用 <a href=https://creativecommons.org/licenses/by-nc-sa/4.0/ rel=noopener target=_blank><i class="fab fa-fw fa-creative-commons"></i>BY-NC-SA</a> 许可协议。转载请注明出处!</ul></div><div class=post-tags><a href=/tags/Java/ rel=tag># Java</a><a href=/tags/MySQL/ rel=tag># MySQL</a><a href=/tags/Mybatis/ rel=tag># Mybatis</a><a href=/tags/%E7%BC%93%E5%AD%98/ rel=tag># 缓存</a></div><div class=post-nav><div class=post-nav-item><a href=/2020/09/26/%E5%9C%A8%E8%80%81%E4%B8%88%E4%BA%BA%E5%AE%B6%E7%9A%84%E5%B0%8F%E5%B7%A5%E8%AE%B0%E5%9B%9B/ rel=prev title=在老丈人家的小工记四><i class="fa fa-angle-left"></i> 在老丈人家的小工记四</a></div><div class=post-nav-item><a title="Leetcode 2 Add Two Numbers 题解分析" href=/2020/10/11/Leetcode-2-Add-Two-Numbers-%E9%A2%98%E8%A7%A3%E5%88%86%E6%9E%90/ rel=next>Leetcode 2 Add Two Numbers 题解分析 <i class="fa fa-angle-right"></i></a></div></div></footer></article></div><div class=comments id=disqus_thread><noscript>Please enable JavaScript to view the comments powered by Disqus.</noscript></div></div></main><footer class=footer><div class=footer-inner><div class=beian><a href=https://beian.miit.gov.cn/ rel=noopener target=_blank>浙ICP备16002580号-2 </a><img alt src=/uploads/beian.png><a href=https://beian.mps.gov.cn/#/query/webSearch?code=33010602011094 rel=noopener target=_blank>浙公网安备 33010602011094号</a></div><div class=copyright>© <span itemprop=copyrightYear>2026</span><span class=with-love><i class="fa fa-heart"></i> </span><span class=author itemprop=copyrightHolder>Nicksxs</span></div></div></footer><div aria-label=返回顶部 class=back-to-top role=button><i class="fa fa-arrow-up fa-lg"></i><span>0%</span></div><a aria-label="在 GitHub 上关注我" title="在 GitHub 上关注我" class=github-corner href=https://github.com/nicksxs rel=noopener target=_blank><svg viewbox="0 0 250 250" aria-hidden=true height=80 width=80><path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path><path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2" style="transform-origin:130px 106px" class=octo-arm fill=currentColor></path><path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4 L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0 C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6 C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1 C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9 141.8,141.8 Z" class=octo-body fill=currentColor></path></svg></a><noscript><div class=noscript-warning>Theme NexT works best with JavaScript enabled</div></noscript><script crossorigin=anonymous integrity=sha256-XL2inqUJaslATFnHdJOi9GfQ60on8Wx1C2H8DYiN1xY= src=https://cdnjs.cloudflare.com/ajax/libs/animejs/3.2.1/anime.min.js></script><script crossorigin=anonymous integrity=sha256-ytMJGN3toR+a84u7g7NuHm91VIR06Q41kMWDr2pq7Zo= src=https://cdnjs.cloudflare.com/ajax/libs/fancyapps-ui/5.0.28/fancybox/fancybox.umd.js></script><script crossorigin=anonymous integrity=sha256-mOFREFhqmHeQbXpK2lp4nA3qooVgACfh88fpJftLBbc= src=https://cdnjs.cloudflare.com/ajax/libs/lozad.js/1.16.0/lozad.min.js></script><script src=/js/comments.js></script><script src=/js/utils.js></script><script src=/js/next-boot.js></script><script data-algolia-integrity=sha256-DABVk+hYj0mdUzo+7ViJC6cwLahQIejFvC+my2M/wfM= data-algolia-src=https://cdnjs.cloudflare.com/ajax/libs/algoliasearch/4.20.0/algoliasearch-lite.umd.js data-instant-search-integrity=sha256-9242vN47QUX50UG5Gf5XDO1YREWCEJRyXHofh5fsl24= data-instant-search-src=https://cdnjs.cloudflare.com/ajax/libs/instantsearch.js/4.60.0/instantsearch.production.min.js data-search-src=/js/third-party/search/algolia-search.js src=/js/third-party/search/algolia-search-loader.js></script><script src=/js/third-party/fancybox.js></script><script data-cloudflare-page-counter-config type=application/json>{"enable":true,"endpoint":"https://counter.nicksxs.me","site":"nicksxs","local_cache":true,"timeout":5000,"icon":"far fa-eye","item_text":true}</script><script src=/js/cloudflare-page-counter.js></script><script class=next-config data-name=disqus type=application/json>{"enable":true,"shortname":"nicksxs","count":false,"i18n":{"disqus":"disqus"}}</script><script src=/js/third-party/comments/disqus.js></script>
|