MVC中使用jquery uploadify上传图片报302错误

使用jquery uploadify上传图片报302错误研究了半天，发现我上传的action中有根据session判断用户是否登录，如果没有登录就跳到登陆页，所以就出现了302跳转错误。原来更新了flash的版本以后，通过uploadify获取不到session的值。我目前的解决办法是：

Global.asax.cs中：

     /// <summary>
        /// 解决uploadif上传无法获取Cookie的情况
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void Application_BeginRequest(object sender, EventArgs e)
        {
            try
            {
                HttpRequest request = HttpContext.Current.Request;
                foreach (string k in request.Form.Keys)
                {
                    if (k.IndexOf("cookie_") >= 0)
                        AppendingCookies(k.Remove(0, 7), request.Form[k], request);
                }
            }
            catch { }
        }
        private void AppendingCookies(string cookieName, string cookieValue, HttpRequest request)
        {
            HttpCookie hc = request.Cookies.Get(cookieName);
            if (null == hc)
                hc = new HttpCookie(cookieName);
            hc.Value = cookieValue;
            request.Cookies.Set(hc);
        }

上传方法：

        [HttpPost]
        public JsonResult Upload(HttpPostedFileBase fileData)
        {
            string cookie_LoginUserKey = Request.Form["cookie_LoginUserKey"];
            if (realCookie != cookie_LoginUserKey)
            {
                return Json("上传失败");
            }

            if (fileData != null)
            {
                try
                {
                    string CompanyId = ManageProvider.Provider.Current().CompanyId;
                    Sys_Company model = companybll.GetEntity(CompanyId);
                    string CompanyCode = model.Code;
                    string folder = DateTime.Now.ToString("yyyyMM");
                    // 文件上传后的保存路径
                    string filePath = Server.MapPath("~/Uploads/" + CompanyCode + "/Web/" + folder + "/");
                    if (!Directory.Exists(filePath))
                    {
                        Directory.CreateDirectory(filePath);
                    }

                    string fileName = Path.GetFileName(fileData.FileName);// 原始文件名称
                    string fileExtension = Path.GetExtension(fileName); // 文件扩展名
                    string saveName = Guid.NewGuid().ToString() + fileExtension; // 保存文件名称
                    int filesize = fileData.ContentLength / 1024;
                    if (filesize > 1024 || filesize <= 2 || (fileExtension != ".jpg" && fileExtension != ".png" && fileExtension != ".gif"))
                    {
                        return Json(new { Success = false, Message = "上传失败！\r请上传jpg/png格式图片,文件大小不要超过2MB" }, JsonRequestBehavior.AllowGet);

                    }
                    else
                    {
                        fileData.SaveAs(filePath + saveName);
                        return Json(new { Success = true, FilePath = "/Uploads/"  + CompanyCode + "/Web/" + folder +"/"+ saveName, SaveName = saveName });
                    }

                }
                catch (Exception ex)
                {
                    return Json(new { Success = false, Message = ex.Message }, JsonRequestBehavior.AllowGet);
                }
            }
            else
            {
                return Json(new { Success = false, Message = "请选择要上传的文件！" }, JsonRequestBehavior.AllowGet);
            }
        }

视图中：

  $(document).ready(function () {
        $('#file_upload').uploadify({
            uploader: '/School/Sites/Upload',
            swf: '/Content/Scripts/uploadify3.2.1/uploadify.swf',
            buttonText: "请选择上传图片",
            height: 24,
            width: 120,
            'fileExt': '*.jpg;*.gif,*.png',                 //允许上传的文件格式为*.jpg,*.gif,*.png
            //'fileDesc': 'Web Image Files(.JPG,.GIF,.PNG)',  //过滤掉除了*.jpg,*.gif,*.png的文件
            //'queueID': 'fileQueue',
            'sizeLimit': '2048000',                         //最大允许的文件大小为2M
            //'auto': false,                                  //需要手动的提交申请
            'multi': false,                                 //一次只允许上传一张图片
            formData: { @foreach(string k in Request.Cookies.AllKeys)
                {
                    @:'cookie_@(k)' : '@Request.Cookies[k].Value',
                    }
                '': ''
            },

            'onUploadSuccess': function (file, data, response) {
                var obj = jQuery.parseJSON(data); //把返回的Json序列转化为obj对象
                if (obj.Success) {
                    //alert(obj.FilePath);
                    $('#PictureUrl').val(obj.FilePath);
                    $('#pic').attr("src", obj.FilePath);

                    $('#pic').show();
                }
                else
                    alert(obj.Message);
            }
        });
    });