export function exportDataList () {
  return axios.get('/export?tableName=list', { responseType: 'blob' })
}
exportData() {
      exportDataList().then((res) => {
        this.downloadfile(res)
      }).catch((err) => {
        console.log('错误信息', err)
        this.$message.error('下载错误：获取文件流错误')
      })
    },
downloadfile (res) {
      var blob = new Blob([res.data], { type: 'application/octet-stream;charset=UTF-8'})
      var contentDisposition = res.headers['content-disposition']
      var patt = new RegExp('filename=([^;]+\\.[^\\.;]+);*')
      var result = patt.exec(contentDisposition)
      var filename = result[1]
      var downloadElement = document.createElement('a')
      var href = window.URL.createObjectURL(blob) // 创建下载的链接
      var reg = /^["](.*)["]$/g
      downloadElement.style.display = 'none'
      downloadElement.href = href
      downloadElement.download = decodeURI(filename.replace(reg, '$1')) // 下载后文件名
      document.body.appendChild(downloadElement)
      downloadElement.click() // 点击下载
      document.body.removeChild(downloadElement) // 下载完成移除元素
      window.URL.revokeObjectURL(href)
},

axios.get('/export?tableName=list', { responseType: 'blob' }),一定要记得加{ responseType: 'blob' },否则前端接收到的就是乱码!