$.ajaxFileUpload
 (
 {
 url: '/WxManage/Media/UploadImage', //用于文件上传的服务器端请求地址
 secureuri: false, //是否需要安全协议，一般设置为false
 fileElementId: 'postFile', //文件上传域的ID
 type:"post",
 dataType: 'json', //返回值类型 一般设置为json
 success: function(data, status) //服务器成功响应处理函数
 {
 CloseProgressbar();//关闭进度条 设置进度条进度为100
 if (data.status == 1) {
  layer.msg(data.msg, { icon: 1, time: 1000 },function() {
  parent.location.reload();
  });
 } else {
  $("#btnUploadFile").attr("disabled", false);
  layer.msg(data.msg, { icon: 2, time: 1000 }); 
 }
 },
 error: function(data, status, e) //服务器响应失败处理函数
 {
 $("#btnUploadFile").attr("disabled", false);
 CloseProgressbar();
 layer.closeAll("dialog");
 layer.msg("上传失败", { icon: 2, time: 1000 });
 }
 }
 );

[HttpPost]
 public ActionResult UploadImage(HttpPostedFileBase postFile)
 {
 if (postFile == null)
 {
 return Json(BasicConfig.MessageConfig.Fail("上传文件不得为空"));
 }

 try
 {
 string format = postFile.FileName.Split('.').Last();//后缀名
 SaveFile(postFile);
 return Json(BasicConfig.MessageConfig.Success("上传成功"));
 }
 catch (Exception ex)
 {
 return Json(BasicConfig.MessageConfig.Fail("上传失败"));
 }
 }

FileStream fs = new FileStream(fileSavePath, FileMode.Create);
 BinaryWriter bw = new BinaryWriter(fs);
 BinaryReader br = new BinaryReader(postFile[i].InputStream);
 
 int readCount = 0;//单次读取的字节数
 while ((readCount = br.Read(bufferByte, 0, readBufferSize)) > 0)
 {
  bw.Write(bufferByte, 0, readCount);//写入字节到文件流
  bw.Flush();
  saveCount += readCount;//已经上传的进度
  mem.SetValue("Admin_UploadSpeed_" + Session.SessionID, (saveCount * 1.0 / totalCount).ToString("0.00"), 60);//将更新到memcached缓存中
  Thread.Sleep(200);//为了看到明显的过程故意暂停 
 }