// 下载文件
    _downLoad(url, fileName) {
      const url2 = url.replace(/\\/g, "/");
      const xhr = new XMLHttpRequest();
      xhr.open("GET", url2, true);
      xhr.responseType = "blob";
      //xhr.setRequestHeader(‘Authorization‘, ‘Basic a2VybWl0Omtlcm1pdA==‘);
      // 为了避免大文件影响用户体验，建议加loading
      xhr.onload = () => {
        if (xhr.status === 200) {
          // 获取文件blob数据并保存
          saveAs(xhr.response, fileName);
        }
      };
      xhr.send();
    },