通过后台url来下载文件

import axios from 'axios'
import { getToken } from '@/utils/auth'

const mimeMap = {
  xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
  zip: 'application/zip'
}

const baseUrl = process.env.VUE_APP_BASE_API
export function downloadExcel(str, type="xlsx", filename) {
  axios({
    method: 'get',
    url: baseUrl + str,
    responseType: 'blob',
    headers: { 'Authorization': 'Bearer ' + getToken() }
  }).then(res => {
    resolveBlob(res, mimeMap[type])
  })
}
/**
 * 解析blob响应内容并下载
 * @param {*} res blob响应内容
 * @param {String} mimeType MIME类型
 */
export function resolveBlob(res, mimeType) {
  var blob = new Blob([res.data], { type: mimeType });
  //从response的headers中获取filename, 后端response.setHeader("Content-disposition", "attachment; filename=xxxx.xlsx") 设置的文件名;
  var patt = new RegExp('filename=([^;]+\\.[^\\.;]+);*');
  var contentDisposition = decodeURI(res.headers['content-disposition']);
  var result = patt.exec(contentDisposition);
  var fileName = result[1];
  fileName = fileName.replace(/\"/g, '');
  const ObjectUrl = URL.createObjectURL(blob);

  // 对于<a>标签，只有 Firefox 和 Chrome（内核）支持 download 属性
  if ('download' in document.createElement('a')) {
    const aLink = document.createElement('a');
    aLink.href = ObjectUrl;
    aLink.setAttribute('download', fileName) // 设置下载文件名称
    document.body.appendChild(aLink)
    aLink.click()
    window.URL.revokeObjectURL(ObjectUrl) // 释放URL 对象
  } else {
    // IE 浏览器兼容方法
    window.navigator.msSaveBlob(blob, fileName)
  }
}

备注：本质还是拿到后台的文件流数据，然后前端转成二进制文件，通过a标签的download属性来下载