ASP.NET实现同一时间相同账户不可重复登陆

void checkUserLoginOnOrOff()
{
 bool userLoginOnOrOff = false;
 ArrayList list = Application.Get("GLOBAL_USER_LIST") as ArrayList;
 if(list == null)
 {
  list = new ArrayList();
 }
 for(int i = 0 ; i < list.Count ; i++)
 {
  if(txtLoginId.Text.Trim() == (list[i] as string))
  {
   lbl_Err.Text = "检测到账户使用中!请稍后再试...";
   userLoginOnOrOff = true;
   break;
  }
 }
 if(!userLoginOnOrOff)
 {
  list.Add(txtLoginId.Text.Trim());
  Application.Add("GLOBAL_USER_LIST",list)
  Session["ADMIN_USER"] = txtLoginId.Text.Trim();
 }
}

设置SESSION存活期WEB.CONFIG中SYSTEM.WEB中SESSIONSTATE一项的TIMEOUT,其计时单位为分钟

<SESSIONSTATE MODE="INPRC" STATECONNECTIONSTRING="TCPIP=127.0.0.1:49157" SQLCONNECTIONSTRING="DATA SOURCE=127.0.0.1;UID=SA;PWD=;" COOKIEELESS="FALSE" TIMEOUT="1"/>