Use of Listener and Timer in JSP

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Sometimes you need to regularly execute some programs during JSP running, such as collecting traffic and updating cache data. Generally, Listener and Timer are used. The following is a simple application, the purpose is to check whether the program is being executed at any time.

Create a TimerTask

Public class LogTask extends TimerTask {
@ Override
Public void run (){
// TODO Auto-generated method stub
SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd HH: mm: ss ");
System. out. println (sdf. format (new Date () + "-- this programe is running! ");

}
}

Create a listener

Public class LogListener implements ServletContextListener {
Private Timer timer = null;
@ Override
Public void contextDestroyed (ServletContextEvent arg0 ){
// TODO Auto-generated method stub
If (timer! = Null)
{
Timer. cancel ();
}
}

@ Override
Public void contextInitialized (ServletContextEvent arg0 ){
// TODO Auto-generated method stub
If (timer = null)
{
Timer = new Timer ();
Timer. schedule (new LogTask (), new Date (), 1000 );
}
}

}

Configure in web. xml

<Listener>
<Listener-class> org. heroking. web. LogListener </listener-class>
</Listener>