asp.net中显示在线用户

asp.net中显示在线用户
private static System.Threading.Timer timer;
private const int interval = 1000 * 60 * 20;//检查在线用户的间隔时间
/// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.IContainer components = null;
public Global()
{
InitializeComponent();
}
protected void Application_Start(Object sender, EventArgs e)
{
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.Columns.Add("ClientIP");//
userTable.Columns.Add("ClientName");//
userTable.Columns.Add("ClientAgent");//
userTable.PrimaryKey = new DataColumn[]{userTable.Columns[0]};
userTable.AcceptChanges();
Application.Lock();
Application["UserOnLine"] = userTable;
Application.UnLock();
}
protected void Session_Start(Object sender, EventArgs e)
{
}
protected void Application_BeginRequest(Object sender, EventArgs e)
{
}
protected void Application_EndRequest(Object sender, EventArgs e)
{
}
protected void Application_AcquireRequestState(Object sender, EventArgs e)
{
if(sender == null) return;
if(!(sender is HttpApplication)) return;
HttpApplication mApp = (HttpApplication)sender;
if(mApp.Context.Session == null) return;
if(mApp.Context.Session["UserID"]==null ) return;
string userID = mApp.Context.Session["UserID"].ToString();
if(Application["UserOnLine"] == null) return;
if(!(Application["UserOnLine"] is DataTable)) return;
DataTable userTable = (DataTable)Application["UserOnLine"];
DataRow curRow = userTable.Rows.Find(new object[]{userID});
if(curRow != null)
{
this.GetDataRowfromHttpApp(mApp,ref curRow);
}
else
{
DataRow newRow = userTable.NewRow();
this.GetDataRowfromHtt