@Override
 public void sessionCreated(HttpSessionEvent se) {
   // TODO Auto-generated method stub
   SiteStatistics.raise();
 }
 @Override
 public void sessionDestroyed(HttpSessionEvent se) {
   // TODO Auto-generated method stub
   String checked = (String) se.getSession().getAttribute("checked");
   if (checked == null) SiteStatistics.reduce();
 }