[code] 
package com.samagam;
import java.util.HashMap;
import java.util.Hashtable;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionBindingEvent;
 
public class sessionList implements javax.servlet.http.HttpSessionListener, javax.servlet.http.HttpSessionAttributeListener 
{
  private String name = null;
  private HttpSession session = null;
  private String val = null;
  public static Hashtable tb = new Hashtable();
 
  public void sessionCreated(HttpSessionEvent event)
  {
    session = event.getSession();
    tb.put(session,"0");
  }
 
  public void sessionDestroyed(HttpSessionEvent event)
  {
    session = event.getSession();
    tb.remove(session);
  }
 
  public void attributeAdded(HttpSessionBindingEvent event)
  {
    name = (String)event.getName();
    session = event.getSession();
    val = (String)event.getValue();
    if(name.equals("userid")){
    tb.put(session,val);
    }
  }
   public void attributeRemoved(HttpSessionBindingEvent event)
  {
    name = event.getName();
    session = event.getSession();
  }
 
  public void attributeReplaced(HttpSessionBindingEvent event)
  {
    name = event.getName();
    session = event.getSession();
  }
  public static String fnd(String id){
  boolean i;
  String p;
   i = tb.containsValue(id);
   //System.out.println(i);
   if(i){
   p = "yes";
   return p;
   }else{
   p="no";
   return p;
   }
  }
}
 
[/code]