java Web定时器实例

//这是我的定时器类，用来定时执行某段任务；

package com.my.time;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;


public class BugXmlTimer{
publicTimer timer;


public void timerStart(){
timer = new Timer();
Date datetime=new Date();
Date midnightDate=new Date();

SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd");
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

try {

midnightDate = sdf2.parse(sdf1.format(datetime)+" 23:00:00");
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

long in=midnightDate.getTime()-datetime.getTime();

System.out.println("before task");
//立刻执行，然后每隔30s执行一次
timer.schedule(new BugXmlTimerTask(), 0,30000);


}

public void timerStop(){
if(timer!=null)
timer.cancel();
}

public static void main(String[] args){
BugXmlTimer myTimer=new BugXmlTimer();


// TODO Auto-generated method stub
myTimer.timerStart();

}
}

//这是执行任务的类，即每隔一段时间要做的事情在这里

package com.my.time;


import java.util.TimerTask;

public class BugXmlTimerTask extends TimerTask {
@Override
public void run() {
System.out.print("run task");
}
}
//以下是出发定时操作的类，该类继承了ServletContextListener


public class MyTimerListener implements ServletContextListener {
private BugXmlTimermytimer = new BugXmlTimer();
public void contextInitialized(ServletContextEvent event) {
mytimer.timerStart();
}

public void contextDestroyed(ServletContextEvent event) {
mytimer.timerStop();
}
}


然后在web.xml里部署一下，即可在程序启动后运行定时器了！


<listener>
<listener-class>com.my.time.MyTimerListener </listener-class>
</listener>