在服务端推送过来的二进制数组(JSON格式），在前端要处理成JS原生数组以后才能做成Blob，有两个地方要注意（详细注释），代码如下：

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
};