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项目初始化</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ts-axios 基础功能实现</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ts-axios 异常情况处理</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ts-axios 接口扩展</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading open"><span>ts-axios 拦截器实现</span> <span class="arrow down"></span></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/blog/pages/70651900f022f586/" aria-current="page" class="active sidebar-link">拦截器设计与实现</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header level2"><a href="/blog/pages/70651900f022f586/#需求分析" class="sidebar-link">需求分析</a></li><li class="sidebar-sub-header level2"><a href="/blog/pages/70651900f022f586/#整体设计" class="sidebar-link">整体设计</a></li><li class="sidebar-sub-header level2"><a href="/blog/pages/70651900f022f586/#拦截器管理类实现" class="sidebar-link">拦截器管理类实现</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header level3"><a href="/blog/pages/70651900f022f586/#接口定义" class="sidebar-link">接口定义</a></li><li class="sidebar-sub-header level3"><a href="/blog/pages/70651900f022f586/#代码实现" class="sidebar-link">代码实现</a></li></ul></li><li class="sidebar-sub-header level2"><a href="/blog/pages/70651900f022f586/#链式调用实现" class="sidebar-link">链式调用实现</a></li><li class="sidebar-sub-header level2"><a href="/blog/pages/70651900f022f586/#demo-编写" class="sidebar-link">demo 编写</a></li></ul></li></ul></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ts-axios 配置化实现</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ts-axios 取消功能实现</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ts-axios 更多功能实现</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ts-axios 单元测试</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>ts-axios 部署与发布</span> <span class="arrow right"></span></p> <!----></section></li></ul> </aside> <div><main class="page"><div class="theme-vdoing-wrapper "><div class="articleInfo-wrap" data-v-06970110><div class="articleInfo" data-v-06970110><ul class="breadcrumbs" data-v-06970110><li data-v-06970110><a href="/blog/" title="首页" class="iconfont icon-home router-link-active" data-v-06970110></a></li> <li data-v-06970110><a href="/blog/note/typescript-axios/#《TypeScript 从零实现 axios》" data-v-06970110>《TypeScript 从零实现 axios》</a></li><li data-v-06970110><a href="/blog/note/typescript-axios/#ts-axios 拦截器实现" data-v-06970110>ts-axios 拦截器实现</a></li></ul> <div class="info" data-v-06970110><div title="作者" class="author iconfont icon-touxiang" data-v-06970110><a href="javascript:;" data-v-06970110>HuangYi</a></div> <div title="创建时间" class="date iconfont icon-riqi" data-v-06970110><a href="javascript:;" data-v-06970110>2020-01-05</a></div> <!----></div></div></div> <!----> <div class="content-wrapper"><div class="right-menu-wrapper"><div class="right-menu-margin"><div class="right-menu-title">目录</div> <div class="right-menu-content"></div></div></div> <h1><img src="data:image/png;base64,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">拦截器设计与实现<!----></h1>  <div class="theme-vdoing-content content__default"><p>拦截器设计与实现</p> <h2 id="需求分析"><a href="#需求分析" class="header-anchor">#</a> 需求分析</h2> <p>我们希望能对请求的发送和响应做拦截，也就是在发送请求之前和接收到响应之后做一些额外逻辑。</p> <p>我们希望设计的拦截器的使用方式如下：</p> <div class="language-typescript line-numbers-mode"><pre class="language-typescript"><code><span class="token comment">// 添加一个请求拦截器</span>
axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span><span class="token keyword">function</span> <span class="token punctuation">(</span>config<span class="token punctuation">)</span> <span class="token punctuation">{</span>
  <span class="token comment">// 在发送请求之前可以做一些事情</span>
  <span class="token keyword">return</span> config<span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token keyword">function</span> <span class="token punctuation">(</span>error<span class="token punctuation">)</span> <span class="token punctuation">{</span>
  <span class="token comment">// 处理请求错误</span>
  <span class="token keyword">return</span> <span class="token builtin">Promise</span><span class="token punctuation">.</span><span class="token function">reject</span><span class="token punctuation">(</span>error<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 添加一个响应拦截器</span>
axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>response<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span><span class="token keyword">function</span> <span class="token punctuation">(</span>response<span class="token punctuation">)</span> <span class="token punctuation">{</span>
  <span class="token comment">// 处理响应数据</span>
  <span class="token keyword">return</span> response<span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token keyword">function</span> <span class="token punctuation">(</span>error<span class="token punctuation">)</span> <span class="token punctuation">{</span>
  <span class="token comment">// 处理响应错误</span>
  <span class="token keyword">return</span> <span class="token builtin">Promise</span><span class="token punctuation">.</span><span class="token function">reject</span><span class="token punctuation">(</span>error<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br></div></div><p>在 <code>axios</code> 对象上有一个 <code>interceptors</code> 对象属性，该属性又有 <code>request</code> 和 <code>response</code> 2 个属性，它们都有一个 <code>use</code> 方法，<code>use</code> 方法支持 2 个参数，第一个参数类似 Promise 的 <code>resolve</code> 函数，第二个参数类似 Promise 的 <code>reject</code> 函数。我们可以在 <code>resolve</code> 函数和 <code>reject</code> 函数中执行同步代码或者是异步代码逻辑。</p> <p>并且我们是可以添加多个拦截器的，拦截器的执行顺序是链式依次执行的方式。对于 <code>request</code> 拦截器，后添加的拦截器会在请求前的过程中先执行；对于 <code>response</code> 拦截器，先添加的拦截器会在响应后先执行。</p> <div class="language-typescript line-numbers-mode"><pre class="language-typescript"><code>axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span>config <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  config<span class="token punctuation">.</span>headers<span class="token punctuation">.</span>test <span class="token operator">+=</span> <span class="token string">'1'</span>
  <span class="token keyword">return</span> config
<span class="token punctuation">}</span><span class="token punctuation">)</span>
axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span>config <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  config<span class="token punctuation">.</span>headers<span class="token punctuation">.</span>test <span class="token operator">+=</span> <span class="token string">'2'</span>
  <span class="token keyword">return</span> config
<span class="token punctuation">}</span><span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><p>此外，我们也可以支持删除某个拦截器，如下：</p> <div class="language-typescript line-numbers-mode"><pre class="language-typescript"><code><span class="token keyword">const</span> myInterceptor <span class="token operator">=</span> axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span><span class="token keyword">function</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token comment">/*...*/</span><span class="token punctuation">}</span><span class="token punctuation">)</span>
axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">eject</span><span class="token punctuation">(</span>myInterceptor<span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><h2 id="整体设计"><a href="#整体设计" class="header-anchor">#</a> 整体设计</h2> <p>我们先用一张图来展示一下拦截器工作流程：</p> <p><img src="https://cdn.jsdelivr.net/gh/xugaoyi/image_store/blog/20200105110744.png" alt="interceptor" title="interceptor"></p> <p>整个过程是一个链式调用的方式，并且每个拦截器都可以支持同步和异步处理，我们自然而然地就联想到使用 Promise 链的方式来实现整个调用过程。</p> <p>在这个 Promise 链的执行过程中，请求拦截器 <code>resolve</code> 函数处理的是 <code>config</code> 对象，而相应拦截器 <code>resolve</code> 函数处理的是 <code>response</code> 对象。</p> <p>在了解了拦截器工作流程后，我们先要创建一个拦截器管理类，允许我们去添加
删除和遍历拦截器。</p> <h2 id="拦截器管理类实现"><a href="#拦截器管理类实现" class="header-anchor">#</a> 拦截器管理类实现</h2> <p>根据需求，<code>axios</code> 拥有一个 <code>interceptors</code> 对象属性，该属性又有 <code>request</code> 和 <code>response</code> 2 个属性，它们对外提供一个 <code>use</code> 方法来添加拦截器，我们可以把这俩属性看做是一个拦截器管理对象。<code>use</code> 方法支持 2 个参数，第一个是 <code>resolve</code> 函数，第二个是 <code>reject</code> 函数，对于 <code>resolve</code> 函数的参数，请求拦截器是 <code>AxiosRequestConfig</code> 类型的，而响应拦截器是 <code>AxiosResponse</code> 类型的；而对于 <code>reject</code> 函数的参数类型则是 <code>any</code> 类型的。</p> <p>根据上述分析，我们先来定义一下拦截器管理对象对外的接口。</p> <h3 id="接口定义"><a href="#接口定义" class="header-anchor">#</a> 接口定义</h3> <p><code>types/index.ts</code>：</p> <div class="language-typescript line-numbers-mode"><pre class="language-typescript"><code><span class="token keyword">export</span> <span class="token keyword">interface</span> <span class="token class-name">AxiosInterceptorManager<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span></span> <span class="token punctuation">{</span>
  <span class="token function">use</span><span class="token punctuation">(</span>resolved<span class="token operator">:</span> ResolvedFn<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span><span class="token punctuation">,</span> rejected<span class="token operator">?</span><span class="token operator">:</span> RejectedFn<span class="token punctuation">)</span><span class="token operator">:</span> <span class="token builtin">number</span>

  <span class="token function">eject</span><span class="token punctuation">(</span>id<span class="token operator">:</span> <span class="token builtin">number</span><span class="token punctuation">)</span><span class="token operator">:</span> <span class="token keyword">void</span>
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">interface</span> <span class="token class-name">ResolvedFn<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">=</span><span class="token builtin">any</span><span class="token operator">&gt;</span></span> <span class="token punctuation">{</span>
  <span class="token punctuation">(</span>val<span class="token operator">:</span> <span class="token constant">T</span><span class="token punctuation">)</span><span class="token operator">:</span> <span class="token constant">T</span> <span class="token operator">|</span> <span class="token builtin">Promise</span><span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span>
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">interface</span> <span class="token class-name">RejectedFn</span> <span class="token punctuation">{</span>
  <span class="token punctuation">(</span>error<span class="token operator">:</span> <span class="token builtin">any</span><span class="token punctuation">)</span><span class="token operator">:</span> <span class="token builtin">any</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br></div></div><p>这里我们定义了 <code>AxiosInterceptorManager</code> 泛型接口，因为对于 <code>resolve</code> 函数的参数，请求拦截器和响应拦截器是不同的。</p> <h3 id="代码实现"><a href="#代码实现" class="header-anchor">#</a> 代码实现</h3> <div class="language-typescript line-numbers-mode"><pre class="language-typescript"><code><span class="token keyword">import</span> <span class="token punctuation">{</span> ResolvedFn<span class="token punctuation">,</span> RejectedFn <span class="token punctuation">}</span> <span class="token keyword">from</span> <span class="token string">'../types'</span>

<span class="token keyword">interface</span> <span class="token class-name">Interceptor<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span></span> <span class="token punctuation">{</span>
  resolved<span class="token operator">:</span> ResolvedFn<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span>
  rejected<span class="token operator">?</span><span class="token operator">:</span> RejectedFn
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">default</span> <span class="token keyword">class</span> <span class="token class-name">InterceptorManager<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span></span> <span class="token punctuation">{</span>
  <span class="token keyword">private</span> interceptors<span class="token operator">:</span> <span class="token builtin">Array</span><span class="token operator">&lt;</span>Interceptor<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span> <span class="token operator">|</span> <span class="token keyword">null</span><span class="token operator">&gt;</span>

  <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>interceptors <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span>
  <span class="token punctuation">}</span>

  <span class="token function">use</span><span class="token punctuation">(</span>resolved<span class="token operator">:</span> ResolvedFn<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span><span class="token punctuation">,</span> rejected<span class="token operator">?</span><span class="token operator">:</span> RejectedFn<span class="token punctuation">)</span><span class="token operator">:</span> <span class="token builtin">number</span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
      resolved<span class="token punctuation">,</span>
      rejected
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
    <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span>
  <span class="token punctuation">}</span>

  <span class="token function">forEach</span><span class="token punctuation">(</span><span class="token function-variable function">fn</span><span class="token operator">:</span> <span class="token punctuation">(</span>interceptor<span class="token operator">:</span> Interceptor<span class="token operator">&lt;</span><span class="token constant">T</span><span class="token operator">&gt;</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token keyword">void</span><span class="token punctuation">)</span><span class="token operator">:</span> <span class="token keyword">void</span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>interceptor <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
      <span class="token keyword">if</span> <span class="token punctuation">(</span>interceptor <span class="token operator">!==</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token function">fn</span><span class="token punctuation">(</span>interceptor<span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span>

  <span class="token function">eject</span><span class="token punctuation">(</span>id<span class="token operator">:</span> <span class="token builtin">number</span><span class="token punctuation">)</span><span class="token operator">:</span> <span class="token keyword">void</span> <span class="token punctuation">{</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>interceptors<span class="token punctuation">[</span>id<span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token keyword">this</span><span class="token punctuation">.</span>interceptors<span class="token punctuation">[</span>id<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token keyword">null</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br></div></div><p>我们定义了一个 <code>InterceptorManager</code> 泛型类，内部维护了一个私有属性 <code>interceptors</code>，它是一个数组，用来存储拦截器。该类还对外提供了 3 个方法，其中 <code>use</code> 接口就是添加拦截器到 <code>interceptors</code> 中，并返回一个 <code>id</code> 用于删除；<code>forEach</code> 接口就是遍历 <code>interceptors</code> 用的，它支持传入一个函数，遍历过程中会调用该函数，并把每一个 <code>interceptor</code> 作为该函数的参数传入；<code>eject</code> 就是删除一个拦截器，通过传入拦截器的 <code>id</code> 删除。</p> <h2 id="链式调用实现"><a href="#链式调用实现" class="header-anchor">#</a> 链式调用实现</h2> <blockquote><p>本小节需要你对 Promise 掌握和理解，可以前往 <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" target="_blank" rel="noopener noreferrer">mdn<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a> 学习。</p></blockquote> <p>当我们实现好拦截器管理类，接下来就是在 <code>Axios</code> 中定义一个 <code>interceptors</code> 属性，它的类型如下：</p> <div class="language-typescript line-numbers-mode"><pre class="language-typescript"><code><span class="token keyword">interface</span> <span class="token class-name">Interceptors</span> <span class="token punctuation">{</span>
  request<span class="token operator">:</span> InterceptorManager<span class="token operator">&lt;</span>AxiosRequestConfig<span class="token operator">&gt;</span>
  response<span class="token operator">:</span> InterceptorManager<span class="token operator">&lt;</span>AxiosResponse<span class="token operator">&gt;</span>
<span class="token punctuation">}</span>

<span class="token keyword">export</span> <span class="token keyword">default</span> <span class="token keyword">class</span> <span class="token class-name">Axios</span> <span class="token punctuation">{</span>
  interceptors<span class="token operator">:</span> Interceptors

  <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>interceptors <span class="token operator">=</span> <span class="token punctuation">{</span>
      request<span class="token operator">:</span> <span class="token keyword">new</span> <span class="token class-name">InterceptorManager<span class="token operator">&lt;</span>AxiosRequestConfig<span class="token operator">&gt;</span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
      response<span class="token operator">:</span> <span class="token keyword">new</span> <span class="token class-name">InterceptorManager<span class="token operator">&lt;</span>AxiosResponse<span class="token operator">&gt;</span></span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br></div></div><p><code>Interceptors</code> 类型拥有 2 个属性，一个请求拦截器管理类实例，一个是响应拦截器管理类实例。我们在实例化 <code>Axios</code> 类的时候，在它的构造器去初始化这个 <code>interceptors</code> 实例属性。</p> <p>接下来，我们修改 <code>request</code> 方法的逻辑，添加拦截器链式调用的逻辑：</p> <p><code>core/Axios.ts</code>：</p> <div class="language-typescript line-numbers-mode"><pre class="language-typescript"><code><span class="token keyword">interface</span> <span class="token class-name">PromiseChain</span> <span class="token punctuation">{</span>
  resolved<span class="token operator">:</span> ResolvedFn <span class="token operator">|</span> <span class="token punctuation">(</span><span class="token punctuation">(</span>config<span class="token operator">:</span> AxiosRequestConfig<span class="token punctuation">)</span> <span class="token operator">=&gt;</span> AxiosPromise<span class="token punctuation">)</span>
  rejected<span class="token operator">?</span><span class="token operator">:</span> RejectedFn
<span class="token punctuation">}</span>

<span class="token function">request</span><span class="token punctuation">(</span>url<span class="token operator">:</span> <span class="token builtin">any</span><span class="token punctuation">,</span> config<span class="token operator">?</span><span class="token operator">:</span> <span class="token builtin">any</span><span class="token punctuation">)</span><span class="token operator">:</span> AxiosPromise <span class="token punctuation">{</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token keyword">typeof</span> url <span class="token operator">===</span> <span class="token string">'string'</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>config<span class="token punctuation">)</span> <span class="token punctuation">{</span>
      config <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    config<span class="token punctuation">.</span>url <span class="token operator">=</span> url
  <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
    config <span class="token operator">=</span> url
  <span class="token punctuation">}</span>

  <span class="token keyword">const</span> chain<span class="token operator">:</span> PromiseChain<span class="token punctuation">[</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">{</span>
    resolved<span class="token operator">:</span> dispatchRequest<span class="token punctuation">,</span>
    rejected<span class="token operator">:</span> <span class="token keyword">undefined</span>
  <span class="token punctuation">}</span><span class="token punctuation">]</span>

  <span class="token keyword">this</span><span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>interceptor <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
    chain<span class="token punctuation">.</span><span class="token function">unshift</span><span class="token punctuation">(</span>interceptor<span class="token punctuation">)</span>
  <span class="token punctuation">}</span><span class="token punctuation">)</span>

  <span class="token keyword">this</span><span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>response<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>interceptor <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
    chain<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>interceptor<span class="token punctuation">)</span>
  <span class="token punctuation">}</span><span class="token punctuation">)</span>

  <span class="token keyword">let</span> promise <span class="token operator">=</span> <span class="token builtin">Promise</span><span class="token punctuation">.</span><span class="token function">resolve</span><span class="token punctuation">(</span>config<span class="token punctuation">)</span>

  <span class="token keyword">while</span> <span class="token punctuation">(</span>chain<span class="token punctuation">.</span>length<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">const</span> <span class="token punctuation">{</span> resolved<span class="token punctuation">,</span> rejected <span class="token punctuation">}</span> <span class="token operator">=</span> chain<span class="token punctuation">.</span><span class="token function">shift</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">!</span>
    promise <span class="token operator">=</span> promise<span class="token punctuation">.</span><span class="token function">then</span><span class="token punctuation">(</span>resolved<span class="token punctuation">,</span> rejected<span class="token punctuation">)</span>
  <span class="token punctuation">}</span>

  <span class="token keyword">return</span> promise
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br></div></div><p>首先，构造一个 <code>PromiseChain</code> 类型的数组 <code>chain</code>，并把 <code>dispatchRequest</code> 函数赋值给 <code>resolved</code> 属性；接着先遍历请求拦截器插入到 <code>chain</code> 的前面；然后再遍历响应拦截器插入到 <code>chain</code> 后面。</p> <p>接下来定义一个已经 resolve 的 <code>promise</code>，循环这个 <code>chain</code>，拿到每个拦截器对象，把它们的 <code>resolved</code> 函数和 <code>rejected</code> 函数添加到 <code>promise.then</code> 的参数中，这样就相当于通过 Promise 的链式调用方式，实现了拦截器一层层的链式调用的效果。</p> <p>注意我们拦截器的执行顺序，对于请求拦截器，先执行后添加的，再执行先添加的；而对于响应拦截器，先执行先添加的，后执行后添加的。</p> <h2 id="demo-编写"><a href="#demo-编写" class="header-anchor">#</a> demo 编写</h2> <p>在 <code>examples</code> 目录下创建 <code>interceptor</code> 目录，在 <code>interceptor</code> 目录下创建 <code>index.html</code>:</p> <div class="language-html line-numbers-mode"><pre class="language-html"><code><span class="token doctype"><span class="token punctuation">&lt;!</span><span class="token doctype-tag">DOCTYPE</span> <span class="token name">html</span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>html</span> <span class="token attr-name">lang</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>en<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>
  <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>head</span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>meta</span> <span class="token attr-name">charset</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>utf-8<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>title</span><span class="token punctuation">&gt;</span></span>Interceptor example<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>title</span><span class="token punctuation">&gt;</span></span>
  <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>head</span><span class="token punctuation">&gt;</span></span>
  <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>body</span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>script</span> <span class="token attr-name">src</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>/__build__/interceptor.js<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span><span class="token script"></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>script</span><span class="token punctuation">&gt;</span></span>
  <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>body</span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>html</span><span class="token punctuation">&gt;</span></span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><p>接着创建 <code>app.ts</code> 作为入口文件：</p> <div class="language-typescript line-numbers-mode"><pre class="language-typescript"><code><span class="token keyword">import</span> axios <span class="token keyword">from</span> <span class="token string">'../../src/index'</span>

axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span>config <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  config<span class="token punctuation">.</span>headers<span class="token punctuation">.</span>test <span class="token operator">+=</span> <span class="token string">'1'</span>
  <span class="token keyword">return</span> config
<span class="token punctuation">}</span><span class="token punctuation">)</span>
axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span>config <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  config<span class="token punctuation">.</span>headers<span class="token punctuation">.</span>test <span class="token operator">+=</span> <span class="token string">'2'</span>
  <span class="token keyword">return</span> config
<span class="token punctuation">}</span><span class="token punctuation">)</span>
axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>request<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span>config <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  config<span class="token punctuation">.</span>headers<span class="token punctuation">.</span>test <span class="token operator">+=</span> <span class="token string">'3'</span>
  <span class="token keyword">return</span> config
<span class="token punctuation">}</span><span class="token punctuation">)</span>

axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>response<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span>res <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  res<span class="token punctuation">.</span>data <span class="token operator">+=</span> <span class="token string">'1'</span>
  <span class="token keyword">return</span> res
<span class="token punctuation">}</span><span class="token punctuation">)</span>
<span class="token keyword">let</span> interceptor <span class="token operator">=</span> axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>response<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span>res <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  res<span class="token punctuation">.</span>data <span class="token operator">+=</span> <span class="token string">'2'</span>
  <span class="token keyword">return</span> res
<span class="token punctuation">}</span><span class="token punctuation">)</span>
axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>response<span class="token punctuation">.</span><span class="token function">use</span><span class="token punctuation">(</span>res <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  res<span class="token punctuation">.</span>data <span class="token operator">+=</span> <span class="token string">'3'</span>
  <span class="token keyword">return</span> res
<span class="token punctuation">}</span><span class="token punctuation">)</span>

axios<span class="token punctuation">.</span>interceptors<span class="token punctuation">.</span>response<span class="token punctuation">.</span><span class="token function">eject</span><span class="token punctuation">(</span>interceptor<span class="token punctuation">)</span>

<span class="token function">axios</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
  url<span class="token operator">:</span> <span class="token string">'/interceptor/get'</span><span class="token punctuation">,</span>
  method<span class="token operator">:</span> <span class="token string">'get'</span><span class="token punctuation">,</span>
  headers<span class="token operator">:</span> <span class="token punctuation">{</span>
    test<span class="token operator">:</span> <span class="token string">''</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">then</span><span class="token punctuation">(</span><span class="token punctuation">(</span>res<span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
  <span class="token builtin">console</span><span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>res<span class="token punctuation">.</span>data<span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br></div></div><p>该 demo 我们添加了 3 个请求拦截器，添加了 3 个响应拦截器并删除了第二个。运行该 demo 我们通过浏览器访问，我们发送的请求添加了一个 <code>test</code> 的请求 header，它的值是 <code>321</code>；我们的响应数据返回的是 <code>hello</code>，经过响应拦截器的处理，最终我们输出的数据是 <code>hello13</code>。</p> <p>至此，我们给 <code>ts-axios</code> 实现了拦截器功能，它是一个非常实用的功能，在实际工作中我们可以利用它做一些需求如登录权限认证。</p> <p>我们目前通过 <code>axios</code> 发送请求，往往会传入一堆配置，但是我们也希望 <code>ts-axios</code> 本身也会有一些默认配置，我们把用户传入的自定义配置和默认配置做一层合并。其实，大部分的 JS 库都是类似的玩法。下面一章我们就来实现这个 feature。</p></div></div>  <div class="page-edit"><div class="edit-link"><a href="https://github.com/heBody/blog/edit/master/docs/《TypeScript 从零实现 axios》/07.ts-axios 拦截器实现/01.拦截器设计与实现.md" target="_blank" rel="noopener noreferrer">编辑</a> <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></div> <div class="tags"><a href="/blog/tags/?tag=TypeScript" title="标签">#TypeScript</a></div> <div class="last-updated"><span class="prefix">上次更新:</span> <span class="time">2022/12/15, 12:09:39</span></div></div> <div class="page-nav-wapper"><div class="page-nav-centre-wrap"><a href="/blog/pages/c4489d0bab02cc0c/" class="page-nav-centre page-nav-centre-prev"><div class="tooltip">响应数据支持泛型</div></a> <a href="/blog/pages/937e4de6b81edeca/" class="page-nav-centre page-nav-centre-next"><div class="tooltip">合并配置的设计与实现</div></a></div> <div class="page-nav"><p class="inner"><span class="prev">
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