axios请求拦截器实现数据加载出来之前loading效果

步骤：先用css做一个loading动画，默认为隐藏，在请求拦截器时让动画显示，在响应拦截器中让动画隐藏

首先我们在template中写html

<template>

  <div id="app">

    <div id="content">

      <div class="box" v-show="flag">

        <div class="loader">

          <div class="loading-3">

            <span></span>

            <span></span>

            <span></span>

            <span></span>

            <span></span>

            <span></span>

            <span></span>

            <span></span>

          </div>

        </div>

      </div>

      <router-view/>

    </div>

  </div>

</template>

然后在css中写样式

   .box {
    width: 100%;
    padding: 3%;
    box-sizing: border-box;
    overflow: hidden;
    margin-left: 110px;
    margin-top: 150px;
  }

  .box .loader {
    width: 30%;
    float: left;
    height: 200px;
    margin-right: 3%;
    box-sizing: border-box;
    display: flex;
    align-items: center;
    justify-content: center
  }

  @-webkit-keyframes loading-3 {
    50% {
      transform: scale(.4);
      opacity: .3
    }
    100% {
      transform: scale(1);
      opacity: 1
    }
  }

  .loading-3 {
    position: relative
  }

  .loading-3 span {
    display: block;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    background-color: #333;
    position: absolute
  }

  .loading-3 span:nth-of-type(1) {
    top: 25px;
    left: 0;
    -webkit-animation: loading-3 1s ease 0s infinite
  }

  .loading-3 span:nth-of-type(2) {
    top: 17px;
    left: 17px;
    -webkit-animation: loading-3 1s ease -.12s infinite
  }

  .loading-3 span:nth-of-type(3) {
    top: 0;
    left: 25px;
    -webkit-animation: loading-3 1s ease -.24s infinite
  }

  .loading-3 span:nth-of-type(4) {
    top: -17px;
    left: 17px;
    -webkit-animation: loading-3 1s ease -.36s infinite
  }

  .loading-3 span:nth-of-type(5) {
    top: -25px;
    left: 0;
    -webkit-animation: loading-3 1s ease -.48s infinite
  }

  .loading-3 span:nth-of-type(6) {
    top: -17px;
    left: -17px;
    -webkit-animation: loading-3 1s ease -.6s infinite
  }

  .loading-3 span:nth-of-type(7) {
    top: 0;
    left: -25px;
    -webkit-animation: loading-3 1s ease -.72s infinite
  }

  .loading-3 span:nth-of-type(8) {
    top: 17px;
    left: -17px;
    -webkit-animation: loading-3 1s ease -.84s infinite
  }

然后在created钩子函数中写拦截器

created(){
            axios.interceptors.request.use((config)=>{
                // 在发送请求之前做些什么
                this.flag = true
                //请求时让loading动画显示
                return config;
            }, function (error) {
                // 对请求错误做些什么
                return Promise.reject(error);
            });

            // 添加响应拦截器
            axios.interceptors.response.use((response)=> {
                // 对响应数据做点什么
                this.flag = false
                //让loading动画隐藏
                return response;
            }, function (error) {
                // 对响应错误做点什么
                return Promise.reject(error);
            });
        }

小结：总的来说就是使用请求拦截器和响应拦截器在控制loading动画的显示隐藏，想在哪使用就在相应的组件中编写即可，我需要的是全局的所以是在app.vue中写的