Vue.prototype.$downloadFile = (filename, data) => {
 if (!data) return;
 let arr8 = Uint8Array.from(data); //！！！注意1：应根据数据的类型选择适当的JS原生数组类型进行转换，也就是说服务端推送的byte型数组还是int型数组等。
 //定义文件内容，类型必须为Blob 否则createObjectURL会报错
 let blob = null;
 let type = 'application/octet-binary';
 if (typeof (window.Blob) == "function") {
  blob = new Blob([arr8], {//！！！注意2：数组两边必须加上[]
   type: type
  });
 } else {
  let BlobBuilder = window.BlobBuilder || window.MozBlobBuilder || window.WebKitBlobBuilder || window.MSBlobBuilder;
  let bb = new BlobBuilder();
  bb.append([arr8]);
  blob = bb.getBlob(type);
 }
 let URL = window.URL || window.webkitURL;
 let bloburl = URL.createObjectURL(blob);
 let anchor = document.createElement("a");
 if ('download' in anchor) {
  anchor.style.visibility = "hidden";
  anchor.href = bloburl;
  anchor.download = filename;
  document.body.appendChild(anchor);
  let evt = document.createEvent("MouseEvents");
  evt.initEvent("click", true, true);
  anchor.dispatchEvent(evt);
  document.body.removeChild(anchor);
 } else if (navigator.msSaveBlob) {
  navigator.msSaveBlob(blob, filename);
 } else {
  location.href = bloburl;
 } //移除链接释放资源
};