在线人数

用asp.net显示在线登陆人数及位置
http://topic.csdn.net/t/20041231/16/3692181.html
Global.aspx

 private static System.Threading.Timer timer;
        //检查在线用户的间隔时间默认20分钟  60000 * 20
        private const int interval = 60000 * 5; 

        private void ScheduledWorkCallback(object sender)
        {
            //LastRequestTime 4点 第二个当前事件是4.10 减去20分钟 是 3.50    4点 <  3.50  没有这个数据不删除。
            //                    第二个当前事件是4.40 减去20分钟 是 4.20    4点 <   4.20  删除。
            string filter = "Convert(LastRequestTime,'System.DateTime') < Convert('" + System.DateTime.Now.AddSeconds(-interval / 1000).ToString() + "','System.DateTime')";
            DataTable userTable = (DataTable)Application["UserOnLine"];
            DataRow[] lineOutUsers = userTable.Select(filter);
            for (int i = 0; i < lineOutUsers.Length; i++)
            {
                DataRow curRow = lineOutUsers[i];

                //保存到数据库   
                //XsStudio.Database db = new XsStudio.Database();
                curRow.Delete();

            }
            userTable.AcceptChanges();
            
            Application.Lock();
            Application["UserOnLine"] = userTable;
            Application.UnLock();
        }   

          
        protected void Application_Start(object sender, EventArgs e)
        {
            //在global.asax做一个Timer周期性地检查
            //每隔20分钟执行一次ScheduledWorkCallback函数
            if (timer == null)
                timer = new System.Threading.Timer(new System.Threading.TimerCallback(ScheduledWorkCallback),sender, 0, interval);

            DataTable userTable = new DataTable();
            userTable.Columns.Add("UserID");//用户ID   
            userTable.Columns.Add("UserName");//用户姓名   
            userTable.Columns.Add("FirstRequestTime");//第一次请求的时间   
            userTable.Columns.Add("LastRequestTime");//最后一次请求的时间   

            userTable.PrimaryKey = new DataColumn[] { userTable.Columns[0] };
            userTable.AcceptChanges();



            Application.Lock();
            Application["UserOnLine"] = userTable;
            Application.UnLock();



        }

页面调用

public void online()
        {
            AjaxControl myCtrl = new AjaxControl("Online", this.Page);
            Literal OnLine = myCtrl.AjaxLtr("OnLine");


            if (Session == null) return;
            if (Session["UserID"].ToString() == "0") return;
            string userID = Session["UserID"].ToString();
            string userName = Session["UserName"].ToString();

            DataTable userTable = (DataTable)Application["UserOnLine"];
            DataRow curRow = userTable.Rows.Find(new object[] { userID });
            if (curRow != null)
            {
                this.GetDataRowFromHttpApp(curRow);
            }
            else
            {
                DataRow newRow = userTable.NewRow();
                this.GetDataRowFromHttpApp(newRow);
                userTable.Rows.Add(newRow);
            }
            userTable.AcceptChanges();

            Application.Lock();
            Application["UserOnLine"] = userTable;
            Application.UnLock();

            string Table = "";

            if (userTable.Rows.Count != 0)
            {
                Table = "<ul>";
                for (int i = 0; i < userTable.Rows.Count; i++)
                {
                    Table += "<li class=\"olw1\">" + userTable.Rows[i][1].ToString() + "</li>";
                }
                Table += "</ul>";
                
            }
            OnLine.Text = Table;

            response = myCtrl.GetString();
        }


        public void LogOut()
        {

            DataTable userTable = (DataTable)Application["UserOnLine"];
            DataRow[] lineOutUsers = userTable.Select("UserID=" + Session["UserID"].ToString());
            for (int i = 0; i < lineOutUsers.Length; i++)
            {
                DataRow curRow = lineOutUsers[i];

                //保存到数据库   
                //XsStudio.Database db = new XsStudio.Database();
                curRow.Delete();

            }
            userTable.AcceptChanges();

            Application.Lock();
            Application["UserOnLine"] = userTable;
            Application.UnLock();

            UserHelper.SetUserSession("", "", 2, 0, 0, 0, 0, 0, DateTime.Now);
            Session.Abandon(); 
            response = "Default.aspx";
        }

        private void GetDataRowFromHttpApp(DataRow mRow)
        {
            if (Session == null) return;
            if (Session["UserID"].ToString() == "0") return;
            string userID = Session["UserID"].ToString();
            string userName = Session["UserName"].ToString();

            if (mRow["UserID"].ToString().Length < 1)
            {
                mRow["UserID"] = userID;
                mRow["UserName"] = userName;
                mRow["FirstRequestTime"] = System.DateTime.Now;
            }

            mRow["LastRequestTime"] = System.DateTime.Now;
            //mRow["LastRequestPath"]   =   requestPath;   

        }