解决文件上传插件Uploadify在火狐浏览器下，Session丢失的问题

因为在火狐浏览器下Flash发送的请求不会带有cookie，所以导致后台的session失效。

解决的方法就是手动传递SessionID到后台。

 $("#fileresultfiles").uploadify({
                swf: '/Scripts/uploadify/uploadify.swf',
                uploader: '/UploadFiles.ashx',
                queueID: 'fileQueue',
                buttonText: '附件上传',
                auto: true,
                debug: false,
                removeCompleted: true,
                multi: true,
                displayData: 'speed',
                uploadLimit: 20,
                fileSizeLimit: '500MB',
                formData: {
                    'ASPSESSID': '<%=Session.SessionID %>',
                    'primarykey': $("#<%=hid_resultStrId.ClientID %>").val(),
                },
                onQueueComplete: function (queueData) {
                    //队列上传完成后,ajax获取上传的所有列表
                    AjaxRequestFile();
                },
                onSelectError: function (file, errorCode, errorMsg) {
                    var errorMsg = "";
                    if (errorCode == "QUEUE_LIMIT_EXCEEDED") {
                        errorMsg = "文件数量过多！";
                    }
                    if (errorCode == "-110") {
                        errorMsg = "文件大小超出限制！";
                    }
                    $('#' + file.id).find('.data').html(' errorMsg');
                },
                onUploadSuccess: function (file, data, response) {
                    if (data != "OK") {
                        $("#fileresultfiles").uploadify('cancel', '*');
                        alert(data);
                    }
                }
            });

 'ASPSESSID': '<%=Session.SessionID %>'这句就是把SessionID传递过去

然后在Global.asax文件中监听每一个请求，如果有SessionID传过来就重新设置cookie

        protected void Application_BeginRequest(object sender, EventArgs e)
        {
            //为了Uploadify在谷歌和火狐下不能上传的BUG
            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
            {
            }
        }

        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);//重新设定请求中的cookie值，将服务器端的session值赋值给它
            }
        }