1、实现监听启动的接口

package cn.geekapp.timer;

import java.util.Timer;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class MyListener implements ServletContextListener{
	
	/**
	 * 定时器
	 */
	private static Timer mTimer = null;
	/**
	 * 定时器启动间隔
	 */
	private static final long mPeriod = 1 * 10 * 1000L;//10秒

	@Override
	public void contextDestroyed(ServletContextEvent event) {
		// TODO Auto-generated method stub
		System.out.println("contextDestroyed begin");
		if(mTimer != null){
			mTimer.cancel();
		}
		System.out.println("contextDestroyed end");
	}

	@Override
	public void contextInitialized(ServletContextEvent event) {
		// TODO Auto-generated method stub
		System.out.println("contextInitialized begin");
		mTimer = new Timer(true);
		mTimer.scheduleAtFixedRate(new MyTimerTask(), mPeriod, mPeriod);
		System.out.println("contextInitialized end");
	}

}

2、定义TimerTask

package cn.geekapp.timer;

import java.util.TimerTask;

public class MyTimerTask extends TimerTask{
	
	private static boolean isRun = false; 

	@Override
	public void run() {
		// TODO Auto-generated method stub
		try {
			if(isRun){
				System.out.println("task is running,return!");
				return;
			}
			isRun = true;
			System.out.println("MyTimerTask run at time "+System.currentTimeMillis());
			//业务逻辑代码
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}finally{
			isRun = false;
		}
	}

}

3、web.xml添加监听

  
	cn.geekapp.timer.MyListener
  

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