解决uploadify使用时session发生丢失问题的方法

$("#uploadify").uploadify({ 
 'uploader': '/LZKS/Handler/BigFileUpLoadHandler.ashx', 
 'swf': '/LZKS/Scripts/uploadify/uploadify.swf', 
 'cancelImage': '/LZKS/Scripts/uploadify/cancel.png', 
 'queueID': 'fileQueue', 
 //'auto': false, 
 'multi': true, 
 'buttonText': '文件上传', 
 'formData': { 'ASPSESSID': ASPSESSID, 'AUTHID': auth }, 
 'onSelect': function (file) { 
 $('#uploadify').uploadifySettings('formData', { 'ASPSESSID': ASPSESSID, 'AUTHID': auth }); 
 alert(formDate); 
 }, 
 'onComplete': function (file, data, response) { 
 }, 
 
 'onQueueComplete': function () { 
 alert("上传完成！"); 
 $('#fileQueue').attr('style', 'visibility :hidden'); 
 }, 
 'onSelectError': function (file, errorCode, errorMsg) { 
 $('#fileQueue').attr('style', 'visibility :hidden'); 
 }, 
 'onUploadStart': function (file) { 
 $('#fileQueue').attr('style', 'top:200px;left:400px;width:400px;height :400px;visibility :visible'); 
 } 
 }); 
 }); 

protected void Application_BeginRequest(object sender, EventArgs e) 
 { 
 /* we guess at this point session is not already retrieved by application so we recreate cookie with the session id... */ 
 try 
 { 
 string session_param_name = "ASPSESSID"; 
 string session_cookie_name = "ASP.NET_SessionId"; 
 
 if (HttpContext.Current.Request.Form[session_param_name] != null) 
 { 
 UpdateCookie(session_cookie_name, HttpContext.Current.Request.Form[session_param_name]); 
 } 
 else if (HttpContext.Current.Request.QueryString[session_param_name] != null) 
 { 
 UpdateCookie(session_cookie_name, HttpContext.Current.Request.QueryString[session_param_name]); 
 } 
 } 
 catch 
 { 
 } 
 
 try 
 { 
 string auth_param_name = "AUTHID"; 
 string auth_cookie_name = FormsAuthentication.FormsCookieName; 
 
 if (HttpContext.Current.Request.Form[auth_param_name] != null) 
 { 
 UpdateCookie(auth_cookie_name, HttpContext.Current.Request.Form[auth_param_name]); 
 } 
 else if (HttpContext.Current.Request.QueryString[auth_param_name] != null) 
 { 
 UpdateCookie(auth_cookie_name, HttpContext.Current.Request.QueryString[auth_param_name]); 
 } 
 
 } 
 catch 
 { 
 } 
 } 
 
 private void UpdateCookie(string cookie_name, string cookie_value) 
 { 
 HttpCookie cookie = HttpContext.Current.Request.Cookies.Get(cookie_name); 
 if (null == cookie) 
 { 
 cookie = new HttpCookie(cookie_name); 
 } 
 cookie.Value = cookie_value; 
 HttpContext.Current.Request.Cookies.Set(cookie); 
 } 

var auth = "<% = Request.Cookies[FormsAuthentication.FormsCookieName]==null ? string.Empty : Request.Cookies[FormsAuthentication.FormsCookieName].Value %>"; 
 var ASPSESSID = "<%= Session.SessionID %>"; 

 public class BigFileUpLoadHandler : IHttpHandler, IRequiresSessionState 
 { 
 DALFile Fdal = new DALFile(); 
 public void ProcessRequest(HttpContext context) 
 { 
 context.Response.ContentType = "text/plain"; 
 VideoUpLoad(context, CLSOFT.Web.LZKS.Edu.Globe.filename); 
 } 
 public void VideoUpLoad(HttpContext context, string fileFolderName) 
 { 
 context.Response.Charset = "utf-8"; 
 string aaaaaaa=context.Request.QueryString["sessionid"]; 
 HttpPostedFile file = context.Request.Files["Filedata"]; 
 string uploadPath = HttpContext.Current.Server.MapPath(UploadFileCommon.CreateDir(fileFolderName)); 
 if (file != null) 
 { 
 if (!Directory.Exists(uploadPath)) 
 { 
 Directory.CreateDirectory(uploadPath); 
 } 
 Model.ModelFile model = new Model.ModelFile(); 
 model.File_ID = Guid.NewGuid().ToString(); 
 model.File_Name = file.FileName; 
 model.File_Path = UploadFileCommon.CreateDir(fileFolderName); 
 model.File_Size = file.ContentLength; 
 model.File_Extension = file.FileName.Substring(file.FileName.LastIndexOf('.') + 1); 
 model.File_Date = DateTime.Now; 
 model.File_CurrentMan = CLSOFT.Web.LZKS.Edu.Globe.name; 
 file.SaveAs(uploadPath + model.File_Name); 
 
 List<Model.ModelFile> list = null; 
 if (context.Session["File"] == null) 
 { 
 list = new List<Model.ModelFile>(); 
 } 
 else 
 { 
 list = context.Session["File"] as List<Model.ModelFile>; 
 } 
 list.Add(model); 
 context.Session.Add("File", list); 
 } 
 else 
 { 
 context.Response.Write("0"); 
 } 
 } 

Ext.onReady(function () { 
 Ext.QuickTips.init(); 
 <%--JQuery装载函数--%> 
 $("#uploadify").uploadify({ 
 'uploader': '../Uploadify-v2.1.4/uploadify.swf',//上传swf相对路径 
 'script': '../Service/FileUploadHelper.ashx',//后台上传处理呈现 
 'cancelImg': '../Uploadify-v2.1.4/cancel.png',//取消上传按钮相对路径 
 'checkExisting':true,//服务端重复文件检测 
 'folder': '../UploadFile/',//上传目录 
 'fileExt':'*.jpg;*.png;*.gif;*.bmp',//允许上传的文件格式 
 'fileDesc':'jpg、png、gif、bmp',//文件选择时显示的提示 
 'queueID': 'fileQueue',//上传容器 
 'auto': false, 
 'multi': false,//只允许单文件上传 
 'buttonText':'Choose File', 
 'scriptData': { 'name': '', 'type': '','length':'' },//在加载时此处是null 
 //'onInit':function(){alert("1");},//初始化工作，在Extjs的嵌套中最先触发的函数 
 //选择一个文件后触发 
 'onSelect': function(event, queueID, fileObj) { 
// alert("唯一标识:" + queueID + "\r\n" + 
// "文件名：" + fileObj.name + "\r\n" + 
// "文件大小：" + fileObj.size + "\r\n" + 
// "创建时间：" + fileObj.creationDate + "\r\n" + 
// "最后修改时间：" + fileObj.modificationDate + "\r\n" + 
// "文件类型：" + fileObj.type); 
 $("#uploadify").uploadifySettings("scriptData", { "length": fileObj.size}); //动态更新配(执行此处时可获得值) 
 }, 
 //上传单个文件接收后触发 
 'onComplete': function (event, queueID, fileObj, response, data) { 
 var value = response; 
 if(value==1){ 
 Ext.Msg.alert("提示","上传成功"); 
 } 
 else if(value==0){ 
 Ext.Msg.alert("提示","请选择上传文件"); 
 } 
 else if(value==-1){ 
 Ext.Msg.alert("提示","已存在该文件"); 
 } 
 
 } 
 }); 
 <%-- jQuery装载函数结束--%> 

//动态加载 
 function loadFileType(){ 
 //检测 
 var medianame=Ext.getCmp("eName").getValue(); 
 if(medianame.trim()==""){ 
 Ext.Msg.alert("提示","媒体名称不能为空"); 
 return; 
 } 
 var filetype=Ext.getCmp("eType").getValue(); 
 if(filetype=="" || filetype<0){ 
 Ext.Msg.alert("提示","请选择媒体类型"); 
 return; 
 } 
 //动态更新配(执行此处时可获得值) 
 $("#uploadify").uploadifySettings("scriptData", { "name": medianame,"type":filetype,"sessionuserid":<%=session_userid %> }); 
 //上传开始 
 $('#uploadify').uploadifyUpload(); 
 } 

public class FileUploadHelper : IRequiresSessionState, IHttpHandler 
{ 
 
 int nCurrentUserID = -1; 
 public void ProcessRequest(HttpContext context) 
 { 
 try 
 { 
 nCurrentUserID = WebUtil.GetCurrentUserID();//该处的session值得不到 
 } 
 catch (Exception) 
 { 
 } 
 context.Response.ContentType = "text/plain"; 
 context.Response.Charset = "utf-8"; 
 
 string strFilename = string.Empty; 
 int nFiletype = 0; 
 float fFilelength = 0; 
 string strFileExt = string.Empty; 
 string strFilePath = string.Empty; 
 if (context.Request["sessionuserid"] != null) 
 { 
 nCurrentUserID = Convert.ToInt32(context.Request["sessionuserid"].ToString()); 
 } 
 if (context.Request["name"] != null)//获得文件名(动态参数) 
 { 
 strFilename = context.Request["name"].ToString(); 
 } 
 if (context.Request["type"] != null)//获得文件类型（动态参数） 
 { 
 nFiletype = Convert.ToInt32(context.Request["type"].ToString()); 
 } 
 if (context.Request["length"] != null)//获得文件长度（动态参数） 
 { 
 int nEmptFileLength = Convert.ToInt32(context.Request["length"].ToString()); 
 fFilelength = (float)nEmptFileLength / 1024; 
 } 
 if (context.Request["Filename"] != null)//获得文件名（系统自带） 
 { 
 string filename = context.Request["Filename"].ToString(); 
 strFileExt = Path.GetExtension(filename).ToLower();//获得后缀名 
 } 
 HttpPostedFile file = context.Request.Files["Filedata"]; 
 string uploadPath = HttpContext.Current.Server.MapPath(@context.Request["folder"]); 
 //根据当前日期创建一个文件夹 
 string dirName = System.DateTime.Now.ToString("yyyyMMdd"); 
 uploadPath += dirName; 
 
 string tmpRootDir = context.Server.MapPath(System.Web.HttpContext.Current.Request.ApplicationPath.ToString());//获取程序根目录 
 
 if (file != null) 
 { 
 //判断目录是否存在 
 if (!Directory.Exists(uploadPath)) 
 { 
 Directory.CreateDirectory(uploadPath); 
 } 
 //判断文件是否存在 
 strFilePath = uploadPath + "\\" + strFilename + strFileExt; 
 if (!File.Exists(strFilePath)) 
 { 
 //写数据库成功保存文件 
 Media model = new Media(); 
 int newMediaID = -1; 
 model.media_type = nFiletype; 
 model.media_name = strFilename + strFileExt; 
 model.file_path = strFilePath.Replace(tmpRootDir, "");//保存相对目录 
 model.file_length = fFilelength; 
 newMediaID = MediaBLL.AddMadia(model, nCurrentUserID); 
 if (newMediaID > -1)//数据库写入成功 
 { 
 //保存文件 
 file.SaveAs(strFilePath); 
 //下面这句代码缺少的话，上传成功后上传队列的显示不会自动消失 
 context.Response.Write("1"); 
 } 
 } 
 else 
 { 
 context.Response.Write("-1"); 
 } 
 } 
 else 
 { 
 context.Response.Write("0"); 
 } 
 }