Java定时器Web(转)

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>