几种判断asp.net中session过期方法的比较

                    //登陆成功的情况
                    Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "", "<script>alert('登录成功！')</script>");
                }
                else
                {
                    //过期，重新登录
                    Response.Redirect("LoginForm.aspx");

                }
            }
        }

namespace JudgeSessionOutTime
{
    //1.继承IHttpModule类，实现接口成员
    public class Module:IHttpModule
    {
        #region IHttpModule 成员

        public void Dispose()
        {
            throw new NotImplementedException();
        }

        //2.在Init()方法中对Context进行注册AcquireRequestState事件。
        public void Init(HttpApplication context)
        {
            context.AcquireRequestState+=new EventHandler(context_AcquireRequestState);
        }

        //3.完善AcquireRequestState方法，然后判断session过期
        public void context_AcquireRequestState(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;

            if (app.Context.Session["username"] == null)
            {
                app.Response.Write("<script>alert('session到期！');</script>");
            }
        }

        #endregion
    }
}

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

namespace JudgeSessionOutTime
{
    public class JudgeSession : System.Web.UI.Page
    {
        protected override void OnInit(EventArgs e)
        {
            if (Session["username"] == null)
            {
                Response.Write("session过期!");
            }
            else
            {
                Response.Write("session没有过期，用户名："+Session["username"].ToString());
            }
        }

    }
}