把helloworld.vue改成以下代码：

<template>
  <div class="hello">
    <h1>This is a show file page</h1>
    <h3>导入文件：<input type="file" name="file" @change="showFile($event)" /> </h3><br>
    <textarea v-model="input_text" name="" cols="100" rows="20" placeholder="输入……"></textarea><br><br>
  </div>
</template>

<script>
  export default {
    name: "Hello",
    data: function() {
      return {
        input_text: ''
      }
    },
    methods: {

      showFile(input) {
        //支持chrome IE10
        if (window.FileReader) {
          var file = input.target.files[0];
          var reader = new FileReader();
          reader.onload=((event)=>{
            //显示文件
            this.input_text=event.target.result;
            console.log(event.target.result)
          })
          console.info(file)
          console.info(reader);
          reader.readAsText(file);
        }
        else {
          alert("FileReader Not supported by your browser!");
        }
      }
    }
  }
</script>


<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
  h3 {
    margin: 40px 0 0;
  }
  ul {
    list-style-type: none;
    padding: 0;
  }
  li {
    display: inline-block;
    margin: 0 10px;
  }
  a {
    color: #42b983;
  }
</style>

结果显示，可以把文件内容显示在文本框内，不需要把文件传到后台；