使用前需要先配置cos跨域，不然无法上传文件。
腾讯云cos配置跨域

/**
* @Author: 858834013@qq.com
* @Name: FileUpload
* @Date: 2022-03-04
* @Desc:
*/
<template>
  <div class="upload-file">
    <el-upload list-type="picture-card" action="#" :before-upload="handleBeforeUpload" :file-list="fileList"
               :limit="limit"
               :show-file-list="true" class="upload-file-uploader" ref="upload">
      <!-- 上传按钮 -->
      <i class="el-icon-plus"></i>
      <!-- 上传提示 -->
      <div class="el-upload__tip" slot="tip" v-if="showTip">
        请上传
        <template v-if="fileSize">
          大小不超过
          <b style="color: #f56c6c">{{ fileSize }}MB</b>
        </template>
        <template v-if="fileType">
          格式为
          <b style="color: #f56c6c">{{ fileType.join('/') }}</b>
        </template>
        的文件
      </div>
    </el-upload>
  </div>
</template>

<script>
import configs from '@/config/config'
import { uuid } from 'vue-uuid'
import { getFileName } from '@/utils/auth'

const COS = require('cos-js-sdk-v5')
const Bucket = configs.Bucket
const Region = configs.Region
//创建一个 COS SDK 实例
const cos = new COS({
  SecretId: configs.SecretId,
  SecretKey: configs.SecretKey
})
export default {
  name: 'FileUpload',
  props: {
    // 值
    value: [String, Object, Array],
    // 数量限制
    limit: {
      type: Number,
      default: 5
    },
    // 大小限制(MB)
    fileSize: {
      type: Number,
      default: 5
    },
    // 文件类型, 例如['png', 'jpg', 'jpeg']
    fileType: {
      type: Array,
      default: () => ['png', 'jpg', 'jpeg']
    },
    // 是否显示提示
    isShowTip: {
      type: Boolean,
      default: true
    }
  },
  data() {
    return {
      fileList: [],
      cndUrl: ''
    }
  },
  watch: {
    value: {
      handler(val) {
        if (val) {
          let temp = 1
          // 首先将值转为数组
          const list = Array.isArray(val) ? val : this.value.split(',')
          // 然后将数组转为对象数组
          this.fileList = list.map(item => {
            if (typeof item === 'string') {
              if (item.indexOf(this.cndUrl) === -1) {
                item = { name: item, url: this.cndUrl + item }
              } else {
                item = { name: item, url: item }
              }
            }
            item.uid = item.uid || new Date().getTime() + temp++
            return item
          })
        } else {
          this.fileList = []
          return []
        }
      },
      deep: true,
      immediate: true
    }
  },
  computed: {
    // 是否显示提示
    showTip() {
      return this.isShowTip && (this.fileType || this.fileSize)
    }
  },
  methods: {
    // 上传前校检格式和大小
    handleBeforeUpload(file) {
      // 校检文件类型
      if (this.fileType) {
        let fileExtension = ''
        if (file.name.lastIndexOf('.') > -1) {
          fileExtension = file.name.slice(file.name.lastIndexOf('.') + 1)
        }
        const isTypeOk = this.fileType.some(type => {
          if (file.type.indexOf(type) > -1) return true
          if (fileExtension && fileExtension.indexOf(type) > -1) return true
          return false
        })
        if (!isTypeOk) {
          this.$message.error(`文件格式不正确, 请上传${this.fileType.join('/')}格式文件!`)
          return false
        }
      }
      // 校检文件大小
      if (this.fileSize) {
        const isLt = file.size / 1024 / 1024 < this.fileSize
        if (!isLt) {
          this.$message.error(`上传文件大小不能超过 ${this.fileSize} MB!`)
          return false
        }
      }
      this.uploadFileToTencentClound(file).then(response => {
        console.log(response)
        this.fileList.push({ name: file.uid, url: 'https://' + response })
        this.$emit('input', this.listToString(this.fileList))
      })
    },
    /**上传图片到腾讯云**/
    uploadFileToTencentClound(file) {
      console.log(file)
      console.log('文件名')
      return new Promise(resolve => {
        cos.putObject(
          {
            Bucket: Bucket /* 存储桶 */,
            Region: Region /* 存储桶所在地域，必须字段 */,
            Key: uuid.v1() + '.' + file.name.split('.').pop().toLowerCase() /* 文件名 */,
            StorageClass: 'STANDARD', // 上传模式, 标准模式
            Body: file, // 上传文件对象
            onProgress: function(info) {
              console.log('[cos.postObject-seccess]', JSON.stringify(info))
            }
          },
          function(err, data) {
            console.log('[cos.postObject-err]', err || data)
            resolve(data.Location)
          }
        )
      })
    },
    // 删除文件
    handleDelete(index) {
      this.fileList.splice(index, 1)
      this.$emit('input', this.listToString(this.fileList))
    },
    // 对象转成指定字符串分隔
    listToString(list, separator) {
      let strs = ''
      separator = separator || ','
      for (let i in list) {
        strs += getFileName(list[i].url) + separator
        // strs += list[i].url + separator
      }
      return strs != '' ? strs.substr(0, strs.length - 1) : ''
    }
  }
}
</script>

<style scoped lang="scss">
.upload-file-uploader {
  margin-bottom: 5px;
}

.upload-file-list .el-upload-list__item {
  border: 1px solid #e4e7ed;
  line-height: 2;
  margin-bottom: 10px;
  position: relative;
}

.upload-file-list .ele-upload-list__item-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: inherit;
}

.ele-upload-list__item-content-action .el-link {
  margin-right: 10px;
}
</style>

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