package com.ripsoft.util;

import java.util.Calendar;

import java.util.Timer;

import javax.servlet.ServletContextEvent;

import javax.servlet.ServletContextListener;

public class TimerListener implements ServletContextListener{

    private Timer timer = null;  

    @Override

    public void contextInitialized(ServletContextEvent event) {

        timer = new Timer(true);

        event.getServletContext().log("定时器已启动");  

      //设置执行时间

        Calendar calendar = Calendar.getInstance();

        int year = calendar.get(Calendar.YEAR);

        int month = calendar.get(Calendar.MONTH);

        int day = calendar.get(Calendar.DAY_OF_MONTH);//每天

        //定制每天的11:00:00执行

        calendar.set(year, month, day, 11, 00, 00);

        java.util.Date date = calendar.getTime();

        int period = 30 * 1000;

        //每天的date时刻执行TestTask，每隔30秒重复执行

        timer.schedule(new TestTask(), date, period);

        //每天的date时刻执行TestTask, 仅执行一次

        //timer.schedule(new TestTask(), date);

    }  

    @Override

    public void contextDestroyed(ServletContextEvent event) {

        if (timer != null) {

            timer.cancel();

            event.getServletContext().log("定时器销毁");

        }

    }

}

package com.ripsoft.util;

import java.util.TimerTask;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

public class TestTask extends TimerTask{

    protected final Log logger = LogFactory.getLog(getClass());  

    private static boolean isRunning = false;  

    @Override

    public void run() {

        if (!isRunning) {

            isRunning = true;

            logger.info("开始执行任务。");  

            int i = 0;

            while (i++ < 10) {

                logger.info("已完成任务的" + i + "/" + 10);

            }  

            isRunning = false;

            logger.info("任务执行结束。");  

        } else {

            logger.info("上一次任务执行还未结束，本次任务不能执行。");

        }  

    }

}

    <listener>

        <listener-class>com.ripsoft.util.TimerListener</listener-class>

    </listener>