解决uploadify使用时session发生丢失问题的方法

今天在使用uploadify时发现session会发生丢失的情况，经过一番研究发现，其丢失并不是真正的丢失，而是在使用Flash上传控件的时候使用的session机制和asp.net中的不相同。为解决这个问题使用两种方案，下面进行介绍

第一种：修改Gobal
前台aspx页面：

$("#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');
        }
      });
    });

接着修改Gobal中的代码：

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);
    }

在JS加载前面定义下面两个变量

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

Handler文件代码如下：

 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");
      }
    }

这段代码的功能是将多文件的信息存到context.Session["File"] as List<Model.ModelFileModel.ModelFile>为文件信息类 实现批量上传的信息给Session 
第二种方案：直接向后台传递session值

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--%>

动态的传递参数，并判断是否合法

//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();
  }

<%=session_userid %>是取后台的一个变量，该变量在加载页面的时候获得了session值。当然也可以在前台直接获得session值。 
后台处理程序：

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");
    }
  }

这样就可以解决该问题了。

希望这两种方法都能帮助大家顺利解决session丢失问题，谢谢大家的阅读。