统计在线人数

<%@ Import Namespace="System.Data"%>

void Application_Start(object sender, EventArgs e) 

    {

       //在应用程序启动时运行的代码,网站启动时即出发此事件

        try

        {



            DataTable userTable = new DataTable();

            userTable.Columns.Add("SessionID");

            userTable.Columns.Add("UserIP");

            userTable.Columns.Add("Browser");

            userTable.Columns.Add("OSName");



            userTable.AcceptChanges();

            Application.Lock();

            Application["OnLineusers"] = userTable;

            Application.UnLock();

    }

 

    void Session_Start(object sender, EventArgs e) 

    {

        //在新会话启动时运行的代码，用户访问时会触发Session_Start事件，在Session_Start中记录下该用户的信息，存入表中,
        //Application["OnLineusers"]存放了所有用户的信息


        string sessionid = Session.SessionID;

        string userIP = Request.UserHostAddress;

        HttpBrowserCapabilities bc = Request.Browser;

        string osName = bc.Platform;

        string Browser=bc.Type;



        DataTable userTable = (DataTable)Application["OnLineusers"];

        if (userTable == null) return;

        DataRow[] curRow=userTable.Select("SessionId='"+sessionid+"'");

        if (curRow.Length == 0)

        {

            DataRow newRow = userTable.NewRow();

            newRow["SessionID"] = sessionid;

            newRow[1] = userIP;

            newRow[2] = Browser;

            newRow[3] = osName;

            userTable.Rows.Add(newRow);

            userTable.AcceptChanges();

            Application.Lock();

            Application["OnLineusers"] = userTable;

            Application.UnLock();

             

        }

        

      }

   //移除回话结束的Session
　　void Session_End(object sender, EventArgs e)

    {

        Hashtable onlineuserhash = (Hashtable)Application["OnLineusers"];

        onlineuserhash.Remove(Request.UserHostAddress);



        string sessionid = Session.SessionID;

        DataTable usertable = (DataTable)Application["OnLineusers"];

        if (usertable == null)

        { return; }

        foreach (DataRow row in usertable.Select("SessionID='" + sessionid + "'")) 

        {

            usertable.Rows.Remove(row); 

        }

        usertable.AcceptChanges();

        Application.Lock();

        Application["OnLineusers"] = usertable;

        Application.UnLock();

    }

 常用的解决方法：在项目下建一个txt文件存储在线人数,Session_Start,Session_end对txt进行操作