当前位置：首页 > news >正文

Java定时器Web(转)

news 来源：原创 2024/5/4 20:26:36

通过定时器进行任务的执行是比较常见的情况，下面的是个简单的示例：

主要借助于监听器和TimerTask和Timer类进行实现，另外spring提供了定时器的高级实现好像是quarts。

package com.rx.timer;

import java.util.Date;
import java.util.TimerTask;

public class MyTask extends TimerTask {
    @Override
     public void run() {
        System.out.println( " call at " + ( new Date()));
    }
}

package com.rx.timer;

import java.util.Timer;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class MyListen   implements ServletContextListener {

     private Timer timer = null ;

    @Override
     public void contextDestroyed(ServletContextEvent arg0) {
        timer.cancel();
    }

    @Override
     public void contextInitialized(ServletContextEvent arg0) {
        timer = new Timer( true );
         // 设置任务计划，启动和间隔时间
        timer.schedule( new MyTask(), 0 , 1000 * 10 );
    }
}

<? xml version="1.0" encoding="UTF-8" ?>
< web-app id ="WebApp_ID" version ="2.4" xmlns ="http://java.sun.com/xml/ns/j2ee" xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation ="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" >
     < display-name >
    WebTimer </ display-name >

     < listener >
            < listener-class > com.rx.timer.MyListen </ listener-class >
    </ listener >

     < welcome-file-list >
         < welcome-file > index.jsp </ welcome-file >
     </ welcome-file-list >
</ web-app >

嗯...再转个复杂点的!和上面基本相同，但是在任务执行控制上更细致了

public class WorkServiceImpl implements WorkService , ServletContextListener{

     public void contextDestroyed(ServletContextEvent arg0){
       timer.cancel();
       System.out.println("定时器已销毁");
    }

     public void contextInitialized(ServletContextEvent event){
       timer = new java.util.Timer( true);
       sampleTask =   new SampleTask(event.getServletContext());
       System.out.println("定时器已启动");
       timer.schedule(sampleTask, 0, 60 * 60 * 1000);
       System.out.println("已经添加任务调度表");
    }
}

class SampleTask extends TimerTask{

     private ServletContext context;
     private static boolean isRunning = false; //是否在运行
     private static boolean flag = true;       //跑过一次就不跑了
     private static final int C_SCHEDULE_HOUR = 23; //运行时间
     private WorkServiceImpl workService;

     public SampleTask(ServletContext context){
         this.context = context;
    }

     public void run() {
    workService = new WorkServiceImpl();
        Calendar cal = Calendar.getInstance();
         if (!isRunning){
             if (C_SCHEDULE_HOUR == cal.get(Calendar.HOUR_OF_DAY) && flag){
                isRunning = true;
                workService.autoWorkOff();
                isRunning = false;
                flag = false;
                context.log("指定任务执行结束");
            }
        } else{
            context.log("上一次任务执行还未结束");
        }
         if(C_SCHEDULE_HOUR != cal.get(Calendar.HOUR_OF_DAY)){
            flag = true;
        }
      }
}

在web.xml中配置,如下:
<listener>

<listener-class>com.css.wam.service.impl.WorkServiceImpl</listener-class>

</listener>

转载于:https://www.cnblogs.com/Fskjb/archive/2009/08/24/1553184.html