后端接口返回一个流文件，下载方法

async downLoad(){
      let url= '/downloadTemplate.do';
      this.downloadLoading = true;
      axios.get(url,{
        baseURL: `/web/api`,
        responseType:'blob', //设置响应的数据类型为一个包含二进制数据的 Blob 对象，必须设置
        headers:{Authorization :'Bearer ' + sessionStorage.getItem('access_token')}
      }).then(res => {
          this.downloadLoading = false
          if (!res) {
              this.$message.error("下载模板文件失败");
              return false;
          }
          const blob = new Blob([res.data], {type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=utf-8'});
          const downloadElement = document.createElement('a');
          const href = window.URL.createObjectURL(blob);
          let contentDisposition = res.headers['content-disposition'];  //从response的headers中获取filename, 后端response.setHeader("Content-disposition", "attachment; filename=xxxx.docx") 设置的文件名;
          let patt = new RegExp("filename=([^;]+\\.[^\\.;]+);*");
          let result = patt.exec(contentDisposition);
          let filename = decodeURI(result[1]);
          downloadElement.style.display = 'none';
          downloadElement.href = href;
          downloadElement.download = filename ; //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); //释放掉blob对象
      })
      .catch(function (error) { // 请求失败处理
        console.log(error);
      });
},