$.ajaxFileUpload({
   type: "post",       //请求类型：post或get,当要使用data提交自定义参数时一定要设置为post
   url: "/Shared/Upload",     //文件上传的服务器端请求地址
   secureuri: false,      //是否启用安全提交，一般默认为false就行，不用特殊处理
   fileElementId: "filePicture",   //文件上传控件的id input type="file" id="filePicture" name="filePicture" accept=".jpg,.jpeg,.png,.bmp" onchange="filePictureChange()" />
   dataType: "json",      //返回值类型，一般设置为json，还支持html\xml\script类型
   data: { "id": "1", "name": "test" }, //用于post请求提交自定义参数
   success: function (data, status) {  //服务器成功响应处理函数
   },
   error: function (data, status, e) { //服务器响应失败处理函数
   }
  });

function filePictureChange() {
   $.ajaxFileUpload({
    url: "/Shared/Upload", //用于文件上传的服务器端请求地址
     type: "post",
    secureuri: false, //一般设置为false
    fileElementId: "filePicture", //文件上传空间的id属性
     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
      alert(data.fileName);
     alert(data.filePath);
     alert(data.fileSize);
    },
    error: function (data, status, e){ //服务器响应失败处理函数
      alert(e);
    }
   });
  };

/// summary>
  /// 附件上传
  /// /summary>
  /// returns>/returns>
  public ActionResult Upload()
  {
   HttpFileCollection files = System.Web.HttpContext.Current.Request.Files;
   if (files.Count == 0) return Json("Faild", JsonRequestBehavior.AllowGet);
   MD5 md5Hasher = new MD5CryptoServiceProvider();
   /*计算指定Stream对象的哈希值*/
   byte[] arrbytHashValue = md5Hasher.ComputeHash(files[0].InputStream);
   /*由以连字符分隔的十六进制对构成的String，其中每一对表示value中对应的元素；例如“F-2C-4A”*/
   string strHashData = System.BitConverter.ToString(arrbytHashValue).Replace("-", "");
   string FileEextension = Path.GetExtension(files[0].FileName);
   string uploadDate = DateTime.Now.ToString("yyyyMMdd");
   string virtualPath = string.Format("/Data/ComponentAttachments/{0}/{1}{2}", uploadDate, strHashData, FileEextension);
   string fullFileName = Server.MapPath(virtualPath);
   //创建文件夹，保存文件
    string path = Path.GetDirectoryName(fullFileName);
   Directory.CreateDirectory(path);
   if (!System.IO.File.Exists(fullFileName))
   {
    files[0].SaveAs(fullFileName);
   }
   string fileName = files[0].FileName.Substring(files[0].FileName.LastIndexOf("\\") + 1, files[0].FileName.Length - files[0].FileName.LastIndexOf("\\") - 1);
   string fileSize = GetFileSize(files[0].ContentLength);
   return Json(new { FileName = fileName, FilePath = virtualPath, FileSize = fileSize }, "text/html", JsonRequestBehavior.AllowGet);
  }
  /// summary>
  /// 获取文件大小
  /// /summary>
  /// param name="bytes">/param>
  /// returns>/returns>
  private string GetFileSize(long bytes)
  {
   long kblength = 1024;
   long mbLength = 1024 * 1024;
   if (bytes  kblength)
    return bytes.ToString() + "B";
   if (bytes  mbLength)
    return decimal.Round(decimal.Divide(bytes, kblength), 2).ToString() + "KB";
   else
    return decimal.Round(decimal.Divide(bytes, mbLength), 2).ToString() + "MB";
  }

 uploadHttpData: function (r, type) {
  var data = !type;
  data = type == "xml" || data ? r.responseXML : r.responseText;
  // If the type is "script", eval it in global context
  if (type == "script")
   jQuery.globalEval(data);
  // Get the JavaScript object, if JSON is used.
  if (type == "json")
   eval("data = " + data);
   //eval("data = \"" + data + "\"");
  // evaluate scripts within html
  if (type == "html")
   jQuery("div>").html(data).evalScripts();

  return data;
 },
 handleError: function (s, xhr, status, e) {
  // If a local callback was specified, fire it
  if (s.error) {
   s.error.call(s.context || s, xhr, status, e);
  }

  // Fire the global callback
  if (s.global) {
   (s.context ? jQuery(s.context) : jQuery.event).trigger("ajaxError", [xhr, s, e]);
  }
 }