使用application对象显示在线人数，Global.asax文件

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Security;using System.Web.SessionState;namespace ManageStudent{    public class Global : System.Web.HttpApplication    {        protected void Application_Start(object sender, EventArgs e)        {            //在应用程序启动时运行的代码            //初始化变量：UserCount（）            Application.Lock();//临界变量，使用加锁功能            Application["UserCount"] = 0;            Application.UnLock();//临界变量被解锁        }        protected void Session_Start(object sender, EventArgs e)        {            //在新会话启动时运行的代码            //用户数量加1            Application.Lock();            Application["UserCount"] = Int32.Parse(Application["UserCount"].ToString()) + 1;            Application.UnLock();        }        protected void Application_BeginRequest(object sender, EventArgs e)        {        }        protected void Application_AuthenticateRequest(object sender, EventArgs e)        {        }        protected void Application_Error(object sender, EventArgs e)        {        }        protected void Session_End(object sender, EventArgs e)        {            //在新会话结束时运行的代码            //注意：只有在web.config文件中的sessionstate模式设置为InProc时。            //如果会话模式设置为StateServer或SQLServer，则不会引发该事件            //用户数量减一            Application.Lock();            Application["UserCount"] = Int32.Parse(Application["UserCount"].ToString())- 1;            Application.UnLock();        }        protected void Application_End(object sender, EventArgs e)        {        }    }}

接下来，需要在web.config配置文件中<system,web>标签内添加如下一条语句

 <sessionState mode="InProc"/>

在ApplicationDemo.aspx中写入代码

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ApplicationDemo.aspx.cs" Inherits="ManageStudent.ApplicationDemo" %>        
     
    
      
        
       
       
        
           
      
    
     

 

 

在cs文件中，写入代码，用于显示在线人数

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;namespace ManageStudent{    public partial class ApplicationDemo : System.Web.UI.Page    {        protected void Page_Load(object sender, EventArgs e)        {            if (!Page.IsPostBack)            {                lblUserCount.Text = "网站在线人数：" + Application["UserCount"] + "人";            }        }        protected void btnLogout_Click(object sender, EventArgs e)        {            //销毁Session            Session.Abandon();        }    }}