JAVA-如何实现TIMER功能

JAVA-如何实现TIMER功能

2004-11-8

Author :Meanson Wang

Email:meansonw@hotmail.com

Date:2004-11-8

JAVA-如何实现TIMER功能

1.listener class

package timer;

import java.util.TimerTask;

import java.util.Timer;

import javax.servlet.*;

public class RemindListener implements ServletContextListener {

private java.util.Timer timer = null;

public void contextInitialized(ServletContextEvent sce) {

timer = new java.util.Timer(true);

sce.getServletContext().log(new java.util.Date()+"Timer start up!");

timer.schedule(new RemindTask(),0,1*60*1000);//1 minute roll

sce.getServletContext().log(new java.util.Date()+"Schedule loaded!");

}

public void contextDestroyed(ServletContextEvent sce) {

timer.cancel();

sce.getServletContext().log(new java.util.Date()+"Timer destroyed!");

}

}

2.Task class

package timer;

import java.util.TimerTask;

import java.util.Calendar;

public class RemindTask extends TimerTask{

private static final int C_SCHEDULE_HOUR = 15;

private static boolean isRunning = false;

public RemindTask() {

}

public void run() {

Calendar cal = Calendar.getInstance();

if (!isRunning) {

if (C_SCHEDULE_HOUR == cal.get(Calendar.HOUR_OF_DAY)) {

isRunning = true;

System.out.println(new java.util.Date()+"task start");

//TODO for example

int i = 0;

while (i++ < 10) {

System.out.println(new java.util.Date()+"Done!task" + i + "/" + 10);

}

isRunning = false;

System.out.println(new java.util.Date()+"All task Done!");

}

}

else

{

System.out.println(new java.util.Date()+"Task existed!");

}

}

}

3.loadonstart in web.xml

<listener>

<listener-class>timer.RemindListener</listener-class>

</listener>

4.restart server