统计web应用程序的访问人数

新建一个空网站，添加Global.asax全局处理。

文件目录如图：

在global类中添加代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.SessionState;

namespace WebApplication
{
    public class Global : System.Web.HttpApplication
    {

        protected void Application_Start(object sender, EventArgs e)
        {
            Application["UserCount"] = 0;
        }

        protected void Session_Start(object sender, EventArgs e)
        {
            try
            {
                Application.Lock();
                int countUser = (int)Application["UserCount"];
                Application["UserCount"] = ++countUser;
            }
            catch
            {
            }
            finally
            {
                Application.UnLock();
            }
        }

　　新建一个web窗体applicationstateread类添加在如下代码：

public partial class ApplicationStateRead : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            int userCount = (int)Application["UserCount"];
            Label1.Text = userCount.ToString();
        }
    }public partial class ApplicationStateRead : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            int userCount = (int)Application["UserCount"];
            Label1.Text = userCount.ToString();
        }
    }public partial class ApplicationStateRead : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            int userCount = (int)Application["UserCount"];
            Label1.Text = userCount.ToString();
        }
    }

　　运行效果图：