java、Tomcat定时机制

TimerDemo.java

package com.chase;

import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;

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

public class TimerDemo implements ServletContextListener{
    
     Timer timer;
     
     public TimerDemo() {
         timer = new Timer();
         timer.schedule(new RemindTask(), 10000, 5000);//10000是启动时间，5000是间隔时间
     }

    public void contextDestroyed(ServletContextEvent arg0) {
        System.out.println("contextDestroyed()------------------------------");
        timer.cancel();
        
    }

    public void contextInitialized(ServletContextEvent arg0) {
        System.out.println("contextInitialized()+++++++++++++++++++++++++++++++");//初始化就会运行
//        new TimerDemo();
    }
    
    class RemindTask extends TimerTask{
        @Override
        public void run() {
             String greetings[] = {"--早上好","----上午好","------中午好","-------下午好","--------晚上好"};
             System.out.println(System.currentTimeMillis()+greetings[new Random().nextInt(greetings.length)]);
             String surprise = ShuangSeQiu.surprise(1);
        }
        
    }
    
    public static void main(String[] args) {
        new TimerDemo();
    }

}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  
  
  <listener>  
    <listener-class>com.chase.TimerDemo</listener-class>  
  </listener>
</web-app>