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class="container" id="main-content" tabindex="-1"><div class="post"><article class="post-block h-entry"><div class="post-meta p-author h-card visually-hidden"><img class="author-avatar u-photo" src="../favicon.png" alt="Cytrogen"><span class="p-name">Cytrogen</span><a class="u-url" href="https://cytrogen.icu">https://cytrogen.icu</a></div><a class="post-permalink u-url u-uid visually-hidden" href="https://cytrogen.icu/posts/948f.html">永久链接</a><div class="p-summary visually-hidden"><p>在跟着 IBM 的课程学习全栈开发的时候，期间想到了我于两年前写的一个小项目，当时学习了 Python 的 Flask 框架，就异想天开地编写了一个基于频道的聊天室。当时并不知道实时通信的原理，只是简单地用 Flask 和 SQLite—— 连 Socket.io 都没用上 —— 实现了一个简单的类 Slack 聊天室。</p>
<p>现在见识到了更多的技术，年轻莽撞的我自然是想要重写这个项目。不过具体能不能完成，就是另外一回事了。</p></div><div class="visually-hidden"><a class="p-category" href="../categories/%E7%BC%96%E7%A8%8B%E7%AC%94%E8%AE%B0/">编程笔记</a><a class="p-category" href="../tags/%E5%85%A8%E6%A0%88%E5%AE%9E%E8%B7%B5/">全栈实践</a><a class="p-category" href="../tags/JavaScript/">JavaScript</a><a class="p-category" href="../tags/Node-js/">Node.js</a><a class="p-category" href="../tags/Express-js/">Express.js</a><a class="p-category" href="../tags/React-js/">React.js</a></div><h1 class="post-title p-name">React + Express + Socket.io 之间的实时通信【1】：简单连接</h1><div class="post-info"><time class="post-date dt-published" datetime="2024-01-22T05:06:13.000Z">1/22/2024</time><time class="dt-updated visually-hidden" datetime="2026-02-09T17:16:54.997Z"></time></div><div class="post-content e-content"><html><head></head><body><p>在跟着 IBM 的课程学习全栈开发的时候，期间想到了我于两年前写的一个小项目，当时学习了 Python 的 Flask 框架，就异想天开地编写了一个基于频道的聊天室。当时并不知道实时通信的原理，只是简单地用 Flask 和 SQLite—— 连 Socket.io 都没用上 —— 实现了一个简单的类 Slack 聊天室。</p>
<p>现在见识到了更多的技术，年轻莽撞的我自然是想要重写这个项目。不过具体能不能完成，就是另外一回事了。</p>
<span id="more"></span>
<div class="danger">
<p>阅读本文需知道：</p>
<ul>
<li>我使用 Jetbrains WebStorm 作为 IDE，新建项目也是使用了 WebStorm 提供的模板</li>
<li>写这个文章时我安装的 Node.JS 版本是 <strong> v20.11.0</strong>、npm 版本是 <strong> 10.2.4</strong></li>
</ul>
</div>
<h1 id="项目结构"><a class="markdownIt-Anchor" href="#项目结构"></a> 项目结构</h1>
<p>首先，我们需要新建两个文件夹（废话）：一个是用于存放前端代码的 <code>client</code> 文件夹，另一个是用于存放后端代码的 <code>server</code> 文件夹。</p>
<p>在 WebStorm 中，先在 <code>client</code> 文件夹中新建一个 React 项目，然后在 <code>server</code> 文件夹中新建一个 Express 项目。</p>
<p>总体的项目结构差不多是这样的：</p>
<figure class="highlight plaintext"><table><tbody><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></pre></td><td class="code"><pre><span class="line">总项目（其实不放在一起也OK）/</span><br><span class="line">├─ client/</span><br><span class="line">│ ├─ node_modules/</span><br><span class="line">│ ├─ public/</span><br><span class="line">│ ├─ src/</span><br><span class="line">│ │ ├─ App.js</span><br><span class="line">│ │ ├─ index.js</span><br><span class="line">│ ├─ package.json</span><br><span class="line">├─ server/</span><br><span class="line">│ ├─ bin/</span><br><span class="line">│ │ ├─ www</span><br><span class="line">│ ├─ node_modules/</span><br><span class="line">│ ├─ public/</span><br><span class="line">│ ├─ routes/</span><br><span class="line">│ ├─ views/</span><br><span class="line">│ ├─ app.js</span><br><span class="line">│ ├─ package.json</span><br></pre></td></tr></tbody></table></figure>
<ul>
<li>在 <code>client</code> 文件夹中，最重要的便是 <code>src</code> 文件夹，其中的 <code>App.js</code> 和 <code>index.js</code> 是 React 项目的入口文件</li>
<li>在 <code>server</code> 文件夹中，最重要的便是 <code>app.js</code> 文件。不过由于 <code>bin/www</code> 文件是服务器的启动关键，所以需要修改它而不是 <code>app.js</code> 文件</li>
</ul>
<h1 id="后端"><a class="markdownIt-Anchor" href="#后端"></a> 后端</h1>
<p>我们率先开始装包：</p>
<figure class="highlight bash"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">npm install socket.io cors nodemon</span><br></pre></td></tr></tbody></table></figure>
<p>不装 Express 包自然是因为 WebStorm 已经帮我们装好了，哈哈。</p>
<p>Socket.io 包是我们这次项目的核心。它能够轻松地实现实时通信，也就是多人聊天的基础。Cors 包用于解决跨域问题，比方说我们的前端项目是运行在 <code>localhost:3000</code>，而后端项目是运行在 <code>localhost:4000</code>，这样就会出现跨域问题。而 Nodemon 包是用于自动重启服务器的，这样我们就不用每次修改代码后都手动重启服务器了，懒人福音。</p>
<p>我们直接来看 <code>bin/www</code> 文件。它的一行代码便告诉了我们它的作用：</p>
<figure class="highlight javascript"><table><tbody><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></pre></td><td class="code"><pre><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * Create HTTP server.</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">const</span> server = http.<span class="title function_">createServer</span>(app);</span><br></pre></td></tr></tbody></table></figure>
<p><code>bin/www</code> 创建了一个 HTTP 服务器，而 <code>app</code> 则是我们的 Express 应用。</p>
<p>在导入依赖的地方，我们先导入 Socket.io 和 Cors 包：</p>
<figure class="highlight javascript"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> cors = <span class="built_in">require</span>(<span class="string">'cors'</span>);</span><br><span class="line"><span class="keyword">const</span> { <span class="title class_">Server</span> } = <span class="built_in">require</span>(<span class="string">"socket.io"</span>);</span><br></pre></td></tr></tbody></table></figure>
<p>要想使用 Cors 包，我们就需要激活它：</p>
<figure class="highlight javascript"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">app.<span class="title function_">use</span>(<span class="title function_">cors</span>());</span><br></pre></td></tr></tbody></table></figure>
<p>在 HTTP 服务器被创建之后，我们就需要创建 Socket.io 服务器了：</p>
<figure class="highlight javascript"><table><tbody><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></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> socketIO = <span class="keyword">new</span> <span class="title class_">Server</span>(server, {</span><br><span class="line"> <span class="attr">cors</span>: {</span><br><span class="line"> <span class="attr">origin</span>: <span class="string">"http://localhost:3000"</span></span><br><span class="line"> }</span><br><span class="line">});</span><br></pre></td></tr></tbody></table></figure>
<p>此处的 <code>cors</code> 选项指定了 React 项目的默认端口，为我们之后的前后端通信提供了便利。</p>
<p>接下来，我们需要监听 Socket.io 服务器的连接事件：</p>
<figure class="highlight javascript"><table><tbody><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><td class="code"><pre><span class="line">socketIO.<span class="title function_">on</span>(<span class="string">"connection"</span>, <span class="function">(<span class="params">socket</span>) =></span> {</span><br><span class="line"> <span class="variable language_">console</span>.<span class="title function_">log</span>(<span class="string">`A user connected: <span class="subst">${socket.id}</span>`</span>);</span><br><span class="line"> </span><br><span class="line"> socket.<span class="title function_">on</span>(<span class="string">"disconnect"</span>, <span class="function">() =></span> {</span><br><span class="line"> <span class="variable language_">console</span>.<span class="title function_">log</span>(<span class="string">`A user disconnected: <span class="subst">${socket.id}</span>`</span>);</span><br><span class="line"> });</span><br><span class="line">});</span><br></pre></td></tr></tbody></table></figure>
<p>这个连接事件会在客户端连接到服务器时触发，打印出客户端的 ID。</p>
<p>最后我们要用上最先装的 Nodemon 包。进入 <code>package.json</code> 文件，找到 <code>scripts</code> 选项，将 <code>start</code> 选项改为：</p>
<figure class="highlight json"><table><tbody><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><td class="code"><pre><span class="line"><span class="punctuation">{</span></span><br><span class="line"> <span class="attr">"start"</span><span class="punctuation">:</span> <span class="string">"nodemon ./bin/www"</span></span><br><span class="line"><span class="punctuation">}</span></span><br></pre></td></tr></tbody></table></figure>
<p>至此，我们的 <code>server</code> 目录就可以先不管了。</p>
<h1 id="前端"><a class="markdownIt-Anchor" href="#前端"></a> 前端</h1>
<p>和后端一样，先来装包：</p>
<figure class="highlight bash"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">npm install socket.io-client</span><br></pre></td></tr></tbody></table></figure>
<p>为啥不装 React 包呢？额…… 不皮了。</p>
<p>Socket.io-client 包是用于在前端连接到 Socket.io 服务器的。</p>
<p>其实前端的代码很简单，我们只需要在 <code>App.js</code> 中写入以下代码：</p>
<figure class="highlight javascript"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">import</span> socketIO <span class="keyword">from</span> <span class="string">"socket.io-client"</span>;</span><br><span class="line"><span class="keyword">const</span> socket = socketIO.<span class="title function_">connect</span>(<span class="string">"http://localhost:4000"</span>);</span><br></pre></td></tr></tbody></table></figure>
<p>好了，大功告成，就这么简单。</p>
<h1 id="后话"><a class="markdownIt-Anchor" href="#后话"></a> 后话</h1>
<p>最后只需要在两个项目中分别运行 <code>npm start</code>，然后打开浏览器窗口，访问 <code>localhost:3000</code> 就可以看到服务端的终端输出了。</p>
<p>为什么我要水这么一篇文章呢？因为我觉得这个项目的基础部分还是挺有意思的，而且我也想把我学到的东西记录下来，以便日后查阅。</p>
<p>好吧其实根本就是今天早上睡过头、压根没时间花在代码上，所以一整天就干了这么点实质性的东西。</p>
<p>水文章还是挺好玩的，以后有机会再水一篇。</p>
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