// 发送下载的请求
function downLoadByUrl(url){
   var xhr = new XMLHttpRequest();
   //GET请求,请求路径url,async(是否异步)
   xhr.open('GET', url, true);
   //设置请求头参数的方式,如果没有可忽略此行代码
   xhr.setRequestHeader("token", cookieToken);
   xhr.setRequestHeader("userId", userId);
   //设置响应类型为 blob
   xhr.responseType = 'blob';
   //关键部分
   xhr.onload = function (e) {
      //如果请求执行成功
      if (this.status == 200) {
         let blob = this.response;
         let filename = "XX信息-"+new Date()+".xlsx";//如123.xls
         let a = document.createElement('a');
         blob.type = "application/octet-stream";
         //创键临时url对象
         let url = URL.createObjectURL(blob);
         a.href = url;
         a.download=filename;
         a.click();
         //释放之前创建的URL对象
         window.URL.revokeObjectURL(url);
      }
   };
   //发送请求
   xhr.send();
}