JAVA-如何实现TIMER功能

meanson

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