TrapRefreshPage改进版

捕捉刷新事件
参考了以下文章
http://msdn2.microsoft.com/en-us/library/ms379557(VS.80).aspx

做了一些改进，把计数器放到Cookie中，不使用HttpMoudle，不用在每个按钮事件里加TraceSatae方法，不用每次页面请求时都判断

主要实现类

     public   static   class  RefreshTracker
     {
        Constants#region Constants
        /**//// <summary>
        /// 刷新跟踪记数器
        /// </summary>
        public const string CurrentRefreshCounter = "CurrentRefreshCounter";
        public const string LastRefreshCounter = "LastRefreshCounter";
        public const string HiddenFieldRefreshCounter = "HiddenFieldRefreshtCounter";
        #endregion

       

        private static int GetLastRefreshTicket(HttpContext ctx)
        {
            if (ctx.Request.Cookies[RefreshTracker.LastRefreshCounter] == null)
            {
                HttpCookie cookie = new HttpCookie(LastRefreshCounter, "0");
                ctx.Response.Cookies.Add(cookie);
            }

            return Convert.ToInt32(ctx.Request.Cookies[LastRefreshCounter].Value);
        }
        
        /**//// <summary>
        /// 从HiddenField中取出当前的刷新次数
        /// </summary>
        /// <param name="ctx"></param>
        /// <returns></returns>
        private static int GetCurrentRefreshTicket(HttpContext ctx)
        {
            if (ctx.Request.Cookies[CurrentRefreshCounter] == null)
            {
                ctx.Response.Cookies.Add(new HttpCookie(CurrentRefreshCounter, "0"));
            }

            return Convert.ToInt32(ctx.Request[HiddenFieldRefreshCounter]);
        }
        /**//// <summary>
        /// 更新最后刷新记数器
        /// </summary>
        /// <param name="ctx"></param>
        /// <param name="ticket"></param>
        private static void UpdateLastRefreshCounter(HttpContext ctx, int ticket)
        {
            if (ctx.Request.Cookies[RefreshTracker.LastRefreshCounter] == null)
            {
                HttpCookie cookie = new HttpCookie(LastRefreshCounter, "0");
                ctx.Response.Cookies.Add(cookie);
            }

            ctx.Response.Cookies[LastRefreshCounter].Value = ticket.ToString();
        }

        public static bool Check(HttpContext ctx)
        {


            //从Cookie中读出最后一次刷新记数
            int lastTicket = GetLastRefreshTicket(ctx);

            //从Cookie中读出当前的刷新记数
            int thisTicket = GetCurrentRefreshTicket(ctx);


            // 如果当前刷新记数大于或等于最后次刷新记录数，说明是用户提交
            if (thisTicket > lastTicket ||
                (thisTicket == lastTicket && thisTicket == 0))
            {
                //更新最后一次刷新记数
                UpdateLastRefreshCounter(ctx, thisTicket);
                return false;
            }
            else
            {
                return true;
            }
        }



        /**//// <summary>
        /// 跟踪刷新，当用户点击后，将当前记数器加上1
        /// </summary>
        /// <param name="ctx"></param>
        public static void TrackRefreshState(HttpContext ctx)
        {
            if (ctx.Request.Cookies[CurrentRefreshCounter] == null)
            {
                ctx.Response.Cookies.Add(new HttpCookie(CurrentRefreshCounter, "0"));
            }

            int ticket = Convert.ToInt32(ctx.Request.Cookies[CurrentRefreshCounter].Value) + 1;


            ctx.Response.Cookies[CurrentRefreshCounter].Value = ticket.ToString();


        }

        /**//// <summary>
        /// 保存刷新记数到当前记数器和HiddenField
        /// </summary>
        public static void SaveRefreshState(Page page, HttpContext ctx)
        {
            if (ctx.Request.Cookies[CurrentRefreshCounter] == null)
            {
                ctx.Response.Cookies.Add(new HttpCookie(CurrentRefreshCounter, "0"));
            }

            int ticket = Convert.ToInt32(ctx.Request.Cookies[CurrentRefreshCounter].Value) + 1;
            ctx.Response.Cookies[CurrentRefreshCounter].Value = ticket.ToString();

            //将当前刷新数写入HiddenField,这样，当用户点刷新后，HiddenField中的值不会被加1
            page.ClientScript.RegisterHiddenField(RefreshTracker.HiddenFieldRefreshCounter, ticket.ToString());
        }
     

    }

调用页面和示例代码
CS页

     /**/ /// <summary>
    /// 判断当前的请求是否为用户刷新（如按F5）
    /// </summary>
     public   bool  IsPageRefresh
     {
        get
        {
            return RefreshTracker.Check(this.Context);
        }
    }


     protected   override   void  OnPreRender(EventArgs e)
     {

        base.OnPreRender(e);
        RefreshTracker.SaveRefreshState(this, this.Context);

    }

     protected   override   void  RaisePostBackEvent(IPostBackEventHandler sourceControl,  string  eventArgument)
     {
        RefreshTracker.TrackRefreshState(this.Context);

        base.RaisePostBackEvent(sourceControl, eventArgument);
    }

     protected   void  Button1_Click( object  sender, EventArgs e)
     {
        if (!this.IsPageRefresh)
        {
            Response.Write("Action");
        }
        else
        {
            Response.Write("IsPageRefresh");
        }
    }

HTML页

<% @ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" ValidateRequest="false"  %>


<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >

< html  xmlns ="http://www.w3.org/1999/xhtml"   >
< head  runat ="server" >
     < title > 无标题页 </ title >

     </ head >

< body >
     < form  id ="form1"  runat ="server" >


     < asp:Button  ID ="Button1"  runat ="server"  Text ="Button"  OnClick ="Button1_Click"   />


     </ form >
</ body >
</ html >