此案例是区分上传的文件还是图片；

需要注意的是 before-upload 事件，如果是返回了 false，也会默认走on-remove，需要在 remove事件里做file 的状态判断。

<template>
  <el-upload class="upload-box" ref="uploadImgRef" :file-list="fileList" action="#"
  	:before-upload="onBeforeUploadImage"
    :http-request="uploadAction" :auto-upload="true" :list-type="listType"
    :on-remove="handleRmove"
    :on-preview="handlePictureCardPreview">
    <el-icon v-if="listType === 'picture-card'">
      <Plus />
    </el-icon>
    <el-button v-else type="primary">选择文件</el-button>
  </el-upload>

  <el-dialog v-model="dialogVisible">
    <img style="width: 100%" w-full :src="dialogImageUrl" />
  </el-dialog>
</template>
<script>
import { uploadFile } from '@/api/common';
const PIC_TYPE = 'picture-card'; // 图片格式
  export default {
    props: {
      listType: { // 已上传文件展示格式
        type: String,
        default: 'text'
      },
      fileList: { // 已上传文件列表
        type: Array,
        default: () => []
      },
      fileType: { // 上传文件的格式限制，以逗号分割的字符串，如图片：image/jpeg,image/jpg,image/png
        type: String,
        default: ''
      }
      // 如果还要限制上传的数量，也可匹配；上传之前先检查已有的数量，再进行上传；limit: 10
    },
    emits: ['changeFile'],
    computed: {
      uploadFileType () {
        return this.listType === PIC_TYPE ? 'Img': 'File';
      }
    },
    data () {
      return {
        dialogImageUrl: '',
        dialogVisible: false,
        uploadFileList: []
      }
    },
    mounted () {
      this.uploadFileList = [...this.fileList];
    },
    watch: {
      fileList(val) {
        this.uploadFileList = val
      },
    },
    methods: {

      handlePictureCardPreview (uploadFile) {
        if (this.listType === PIC_TYPE) {
          this.dialogImageUrl = uploadFile.url
          this.dialogVisible = true
        }
      },
      // 上传请求
      async uploadAction (option) {
        try {
          console.log(option, 'option')
          const res = await uploadFile({ file: option.file, fileType: this.uploadFileType });
          const url = res.data.url;
          const name = option.file.name;
          this.uploadFileList.push({url, name});
          this.$emit('changeFile', this.uploadFileType, [...this.uploadFileList]);
        } catch (error) {
          console.log(error)
        }
      },

      onBeforeUploadImage (file) {
        if (!this.fileType) return true;
        const isRightType = this.isRightType(file.type);
        if (!isRightType) {
          this.$message.error(`上传文件格式错误! 请上传 ${this.fileType} 格式文件`)
        }
        return isRightType;
      },

      handleRmove (file, fileList) {
        if (file.status == 'success') {
          // 删除后改变某些状态的代码
          console.log('remove =========');
          const index = this.uploadFileList.findIndex((item) => item.uid === file.uid);
          this.uploadFileList.splice(index, 1);
          this.$emit('changeFile', this.uploadFileType, [...this.uploadFileList]);
        }
        if (file.status == 'ready') {
         // 这里应该就是before-upload中返回false时的状况了，还有没有别的状况，未知
    	}        
      },

      isRightType (type) {
        let isRight = this.fileType.split(',').includes(type);
        return isRight;
      }
    }
  }
</script>
<style lang="scss" scoped>
.upload-box {
  width: 100%;
}
</style>