Question

每当ajax请求发生时，我需要显示一个加载指示器。基于这个问题RxJs How to set default request headers?，我相信我必须创建一个要使用的ajax包装器。

我的要求是在发生请求时启动加载指示器。如果已经有一个请求在运行，它可以重新开始。当请求完成/出错时，我需要取消加载。不过，只有所有请求都完成后，它才能消失。

在axios中，我只使用拦截器并有一个计数器。很简单我真的不知道如何使用RxJS来解决这个问题。我的猜测是它需要做类似的事情，我真的不知道该怎么写。

Answer 1

构建一个自定义HTTP客户端，该客户端公开正在加载的BehaviorSubject。每次打开连接时，增加连接计数，并在每次连接完成时减少计数。当连接数大于0时让您的加载指示器显示，而当连接数大于0时使它隐藏。

class HttpClient {
  constructor() {
   this.connectionCount$ = new rxjs.BehaviorSubject(0);
   this.loading$ = new rxjs.BehaviorSubject(false);
  }
  
  incrementConnectionCount() {
    this.connectionCount$.next(this.connectionCount$.getValue() + 1);
    if (this.connectionCount$.getValue() === 1) {
      this.loading$.next(true);
    }
  }
  
  decrementConnectionCount() {
    this.connectionCount$.next(this.connectionCount$.getValue() - 1);
    if (this.connectionCount$.getValue() === 0) {
      this.loading$.next(false);
    }
  }

  get(url) {
    this.incrementConnectionCount();
    setTimeout(() => { // Simulate a http call that takes 2 seconds
      this.decrementConnectionCount();
    }, 2000);
  }
  
  // Do the same for the other verbs, put, post, delete etc
}

const httpClient = new HttpClient();

// Anywhere you want a loading spinner subscribe to the loading observable and show and hide the spinner
httpClient.loading$.subscribe(loading => {
  document.getElementById('loading').style.display = loading ? 'block' : 'none';
});

// Show the connection count
httpClient.connectionCount$.subscribe(connectionCount => {
  document.getElementById('connectionCount').innerText = connectionCount;
});

// Each time you click the button you will simulate a http get that takes two seconds, press it multople times and it will show for 2 seconds after the last click
document.getElementById('load').addEventListener('click', () => {
  httpClient.get('someUrl');
});

#loading {
  display: none;
}

svg {
  vertical-align: middle;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/6.3.3/rxjs.umd.min.js"></script>

<button id="load">Load</button> Connection count: <span id="connectionCount"></span>

<div id="loading"> <!-- Get a funky loading spinner from loading.io -->
  <svg xmlns="http://www.w3.org/2000/svg" class="lds-cutiefox" width="80px" height="80px" viewBox="0 0 100 100" preserveAspectRatio="xMidYMid">
      <g transform="rotate(80.5368 50 50)">
        <animateTransform attributeName="transform" type="rotate" values="360 50 50;0 50 50" keyTimes="0;1" dur="1.5s" repeatCount="indefinite" calcMode="spline" keySplines="0.5 0 0.5 1" begin="-0.15000000000000002s"/>
        <circle cx="50" cy="50" r="39.891" stroke="#ffc254" stroke-width="14.4" fill="none" stroke-dasharray="0 300">
          <animate attributeName="stroke-dasharray" values="15 300;55.1413599195142 300;15 300" keyTimes="0;0.5;1" dur="1.5s" repeatCount="indefinite" calcMode="linear" keySplines="0 0.4 0.6 1;0.4 0 1 0.6" begin="-0.069s"/>
        </circle>
        <circle cx="50" cy="50" r="39.891" stroke="#fff1cf" stroke-width="7.2" fill="none" stroke-dasharray="0 300">
          <animate attributeName="stroke-dasharray" values="15 300;55.1413599195142 300;15 300" keyTimes="0;0.5;1" dur="1.5s" repeatCount="indefinite" calcMode="linear" keySplines="0 0.4 0.6 1;0.4 0 1 0.6" begin="-0.069s"/>
        </circle>
        <circle cx="50" cy="50" r="32.771" stroke="#000000" stroke-width="1" fill="none" stroke-dasharray="0 300">
          <animate attributeName="stroke-dasharray" values="15 300;45.299378454348094 300;15 300" keyTimes="0;0.5;1" dur="1.5s" repeatCount="indefinite" calcMode="linear" keySplines="0 0.4 0.6 1;0.4 0 1 0.6" begin="-0.069s"/>
        </circle>
        <circle cx="50" cy="50" r="47.171" stroke="#000000" stroke-width="1" fill="none" stroke-dasharray="0 300">
          <animate attributeName="stroke-dasharray" values="15 300;66.03388996804073 300;15 300" keyTimes="0;0.5;1" dur="1.5s" repeatCount="indefinite" calcMode="linear" keySplines="0 0.4 0.6 1;0.4 0 1 0.6" begin="-0.069s"/>
        </circle>
      </g>
      <g transform="rotate(143.103 50 50)">
        <animateTransform attributeName="transform" type="rotate" values="360 50 50;0 50 50" keyTimes="0;1" dur="1.5s" repeatCount="indefinite" calcMode="spline" keySplines="0.5 0 0.5 1"/>

        <path fill="#ffc254" stroke="#000000" d="M97.2,50c0,6.1-1.2,12.2-3.5,17.8l-13.3-5.4c1.6-3.9,2.4-8.2,2.4-12.4"/>
        <path fill="#fff1cf" transform="translate(0,-0.1)" d="M93.6,50c0,1.2,0,2.4-0.1,3.6L93,57.2c-0.4,2-2.3,3.3-4.2,2.8l-0.2-0.1c-1.8-0.5-3.1-2.3-2.7-3.9l0.4-3 c0.1-1,0.1-2,0.1-3"/>
        <path fill="#ffc254" stroke="#000000" d="M85.4,62.5c-0.2,0.7-0.5,1.4-0.8,2.1c-0.3,0.7-0.6,1.4-0.9,2c-0.6,1.1-2,1.4-3.2,0.8v0c-1.1-0.7-1.7-2-1.2-2.9 c0.3-0.6,0.5-1.2,0.8-1.8c0.2-0.6,0.6-1.2,0.7-1.8"/>
        <path fill="#ffc254" stroke="#000000" d="M94.5,65.7c-0.3,0.9-0.7,1.7-1,2.6c-0.4,0.8-0.7,1.7-1.1,2.5c-0.7,1.4-2.3,1.9-3.4,1.3l0,0 c-1.1-0.7-1.5-2.2-0.9-3.4c0.4-0.8,0.7-1.5,1-2.3c0.3-0.8,0.7-1.5,0.9-2.3"/>
        <path fill="#ffc254" stroke="#000000" d="M85.6,67c0,0.8,0.1,1.6,0.3,2.4c0.6-0.5,1.1-1,1.4-1.7c0.2-0.7,0.2-1.5-0.1-2.2C86.5,64,85.6,66.3,85.6,67z"/>

      </g>
      <g transform="rotate(80.5368 50 50)">
        <animateTransform attributeName="transform" type="rotate" values="360 50 50;0 50 50" keyTimes="0;1" dur="1.5s" repeatCount="indefinite" calcMode="spline" keySplines="0.5 0 0.5 1" begin="-0.15000000000000002s"/>

        <path fill="#fff1cf" stroke="#000000" d="M91,33.6l-10,4c-0.4-1.2-1.1-2.4-1.7-3.5c-0.2-0.5,0.3-1.1,0.9-1C83.6,32.9,87.4,32.9,91,33.6z"/>
        <path fill="#fff1cf" stroke="#000000" d="M83.2,36.7l10-4c-0.6-1.7-1.5-3.3-2.3-4.9c-0.3-0.7-1.2-0.6-1.4,0.1C87.6,31.1,85.7,34,83.2,36.7z"/>
        <path fill="#ffc254" stroke="#000000" transform="translate(0,0.2)" d="M82.8,50c0-3.4-0.5-6.8-1.5-10c-0.2-0.8-0.4-1.5-0.3-2.3c0.1-0.8,0.4-1.6,0.7-2.4c0.7-1.5,1.9-3.1,3.7-4l0,0 c1.8-0.9,3.7-1,5.6-0.3c0.9,0.4,1.7,1,2.4,1.8c0.7,0.8,1.3,1.7,1.7,2.8c1.5,4.6,2.2,9.5,2.2,14.4"/>
        <path fill="#fff1cf" transform="translate(0,0.3)" d="M86.4,50l0-0.9l-0.1-0.9l-0.1-1.9c0-0.9,0.2-1.7,0.7-2.3c0.5-0.7,1.3-1.2,2.3-1.4l0.3,0c0.9-0.2,1.9,0,2.6,0.6 c0.7,0.5,1.3,1.4,1.4,2.4l0.2,2.2l0.1,1.1l0,1.1"/>
        <path fill="#000000" d="M88.6,36.6c0.1,0.3-0.2,0.7-0.6,0.8c-0.5,0.2-0.9,0-1.1-0.3c-0.1-0.3,0.2-0.7,0.6-0.8C88,36.1,88.5,36.2,88.6,36.6z"/>
        <path fill="none" stroke="#000000" d="M86,38.7c0.2,0.6,0.8,0.9,1.4,0.7c0.6-0.2,0.9-0.9,0.6-2.1c0.3,1.2,1,1.7,1.6,1.5c0.6-0.2,0.9-0.8,0.8-1.4"/>
        <path fill="#ffc254" stroke="#000000" d="M86.8,42.2l0.4,2.2c0.1,0.4,0.1,0.7,0.2,1.1l0.1,1.1c0.1,1.2-0.9,2.3-2.2,2.3h0c-1.3,0-2.5-0.8-2.5-1.9l-0.1-1 c0-0.3-0.1-0.6-0.2-1l-0.3-1.9"/>
        <path fill="#ffc254" stroke="#000000" d="M96.2,40.2l0.5,2.7c0.1,0.5,0.2,0.9,0.2,1.4l0.1,1.4c0.1,1.5-0.9,2.8-2.2,2.8c-1.3,0-2.5-1.1-2.6-2.4l-0.1-1.2 c0-0.4-0.1-0.8-0.2-1.2l-0.4-2.5"/>
        <path fill="none" stroke="#000000" d="M90.9,36.4c1.1-1.1,2.7-1.6,4.3-1.9"/>
        <path fill="none" stroke="#000000" d="M91.6,37.5c1.3-0.5,2.8-0.8,4.2-0.7"/>
        <path fill="none" stroke="#000000" d="M91.7,38.8c0.2-0.1,0.4-0.1,0.7-0.1c1.2-0.1,2.5,0,3.8,0.3"/>
        <path fill="none" stroke="#000000" d="M85,38.4c-1.6-0.1-3.1,0.6-4.6,1.2"/>
        <path fill="none" stroke="#000000" d="M85,39.5c-1.4,0.3-2.8,0.9-4,1.6"/>
        <path fill="none" stroke="#000000" d="M85.5,40.4c-0.2,0-0.4,0.1-0.7,0.2c-1.1,0.5-2.2,1.1-3.2,1.8"/>
        <path fill="#ff7bac" d="M92.8,34.2c0.1,0.3-0.3,0.8-0.9,1c-0.6,0.2-1.2,0.1-1.4-0.2c-0.1-0.3,0.3-0.8,0.9-1 C92.1,33.8,92.7,33.9,92.8,34.2z"/>
        <path fill="#ff7bac" d="M82.2,38.2c0.1,0.3,0.7,0.3,1.3,0.1c0.6-0.2,1-0.6,0.9-0.9c-0.1-0.3-0.7-0.3-1.3-0.1 C82.5,37.5,82,37.9,82.2,38.2z"/>
        <path fill="#000000" d="M90,35.7L89.3,36l-0.3-0.7c-0.3-0.9,0.1-1.9,0.9-2.3l0.7-0.3l0.3,0.7C91.3,34.4,90.9,35.4,90,35.7z"/>
        <path fill="#000000" d="M85.3,37.4l0.7-0.2l-0.2-0.6c-0.3-0.8-1.3-1.2-2.1-0.8L82.9,36l0.2,0.6C83.5,37.4,84.4,37.7,85.3,37.4z"/>

      </g></svg>
  Loading...
</div>

任何ajax请求上的RxJS加载指示器

1 个答案: