Global.asxa

using System;
using System.Collections;
using System.ComponentModel;
using System.Web;
using System.Web.SessionState;

namespace elcare
{
 /// <summary>
 /// Global 
 /// </summary>
 public class Global : System.Web.HttpApplication
 {
  /// <summary>

  /// </summary>

  private System.ComponentModel.IContainer components = null;

  public Global()
  {
   InitializeComponent();
  } 
  
  protected void Application_Start(Object sender, EventArgs e)
  {
   Application["OL_UserCount"]=0;
  }
 
  protected void Session_Start(Object sender, EventArgs e)
  { 
   Application.Lock();
   Application["OL_UserCount"]=(int)Application["OL_UserCount"]+1;//在线用户
   Application.Add(Session.SessionID.ToString(),1);
   Application.UnLock();
  }

  protected void Application_BeginRequest(Object sender, EventArgs e)
  {
   
  }

  protected void Application_EndRequest(Object sender, EventArgs e)
  {

  }

  protected void Application_AuthenticateRequest(Object sender, EventArgs e)
  {
 
  }

  protected void Application_Error(Object sender, EventArgs e)
  {

  }

  protected void Session_End(Object sender, EventArgs e)
  {
   Application.Lock();
   Application.Remove(Session.SessionID.ToString());
   Application["OL_UserCount"]=(int)Application["OL_UserCount"]-1;
   Application.UnLock();
  }

  protected void Application_End(Object sender, EventArgs e)
  {

  }
   
  #region   /// <summary>
  /// </summary>
  private void InitializeComponent()
  {   
   this.components = new System.ComponentModel.Container();
  }
  #endregion
 }
}

登陆验证
  public void IdPassInSQL()
  {
   string strConn=(String) ((NameValueCollection) Context.GetConfig("system.web/database"))["strConn"];
   using (SqlConnection conn = new SqlConnection(strConn))
   {
    SqlCommand cmd = new SqlCommand("sp_IDPWD",conn);
    cmd.CommandType=CommandType.StoredProcedure;
    cmd.Parameters.Add("@ID",SqlDbType.VarChar,20);
    cmd.Parameters.Add("@PWD",SqlDbType.VarChar,20);
    cmd.Parameters["@ID"].Value=txtName.Text;
    cmd.Parameters["@PWD"].Value=txtPwd.Text;
    conn.Open();

    using (SqlDataReader dr = cmd.ExecuteReader())
    {
     if(dr.Read())
     {
      bool NotOL=true;
      for(int i=0;i<Application.Count;i++)
      {
       if(Application[Application.GetKey(i).ToString()].ToString()==dr["UserID"].ToString())
        NotOL=false;
      }
      if(NotOL)
      {
       Session["UserName"]=dr["UserName"].ToString(); //Session["UserName"] 用户名字
       Session["UserID"]=dr["UserID"].ToString(); //Session["UserID"] 用户ID
       Application[Session.SessionID.ToString()]=dr["UserID"].ToString();//给Session_Start生成的Application付用户ID
       Response.Redirect("./main/main.aspx");
      }
      else
       message.Text="该用户已登陆";
     }
     else
     {
      message.Text="密码错误";
     }
    }
   }
  }

注销退出
  private void btnQuit_Click(object sender, System.EventArgs e)
  {
   Session.Abandon();//该语句将调用Global的Session_End事件
   Response.Write("<script language=javascript>parent.location='../default.aspx'</script>");//
  }