java WEB中的定时器

JAVA WEB定时器,定时器的启动一般随web server的启动而启动,一般有两种方法.

方法一：在web.xml里配置一个Servlet，继承HttpServlet，并设置其随web server的启动而启动。然后在该Servlet的init()方法里启动定时器，在destory()方法里销毁定时器。

方法二：在web.xml里配置一个Listener，继承ServletContextListener，然后在该Listener的初始化方法里启动定时器，在其销毁的方法朝左销毁定时器。

在servlet中启动定时器

一，继承HttpServlet的写法：

1，Servlet

import java.io.IOException;
import java.util.Timer;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ConvergeDataServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;

	private Timer timer1 = null;

	private Task task1;

	/**
	 * Constructor of the object.
	 */
	public ConvergeDataServlet() {
		super();
	}

	/**
	 * Destruction of the servlet.
	 */
	public void destroy() {
		super.destroy();
		if (timer1 != null) {
			timer1.cancel();
		}
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

	// init方法启动定时器
	public void init() throws ServletException {

		ServletContext context = getServletContext();

		// (true为用定时间刷新缓存)
		String startTask = getInitParameter("startTask");

		// 定时刷新时间(分钟)
		Long delay = Long.parseLong(getInitParameter("delay"));

		// 启动定时器
		if (startTask.equals("true")) {
			timer1 = new Timer(true);
			task1 = new Task(context);
			timer1.schedule(task1, delay * 60 * 1000, delay * 60 * 1000);
		}
	}
}

 

2，任务

import java.util.TimerTask;   
  
import javax.servlet.ServletContext;   
  
public class Task extends TimerTask{   
  
    private ServletContext context;   
       
    private static boolean isRunning = true;   
       
    public Task(ServletContext context){   
        this.context = context;   
     }   
       
           
    @Override  
    public void run() {   
        if(isRunning){   
             
         }   
     }   
  
} 

3，web.xml中的配置

< servlet >
     < servlet-name >taskservlet< / servlet-name >
    < servlet-class >com.task< /servlet-class >
    < init-param >
    < param-name >startTask< /param-name >
    < param-value >true< /param-value >
    < /init-param >
    < init-param >
    < param-name >intervalTime< /param-name >
    < param-value >1< /param-value >
    < /init-param >
    < load-on-startup >300< /load-on-startup >
< /servlet >

二，继承ServletContextListener

1，定时器

/**
 * 
 */
package com.annlee.website.util;

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

/**
 * @author Administrator 定时器
 */
public class TimerListener implements ServletContextListener {
	private Timer timer;
	private AnnleeTimerTask task;

	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);
		task = new AnnleeTimerTask(event.getServletContext());
		System.out.println("定时器已启动");
		timer.schedule(task, 0, 60 * 1000);
		System.out.println("已经添加任务调度表");
	}
}

2，任务

package com.annlee.website.util;

import java.util.Calendar;
import java.util.TimerTask;
import javax.servlet.ServletContext;
import com.annlee.website.model.service.member.UsmAccessDataService;

/**
 * 定时器的任务
 */
public class AnnleeTimerTask extends TimerTask {
	private ServletContext context;
	private static boolean isRunning = false;
	private static boolean flag = true;
	private static final int C_SCHEDULE_HOUR = 0;
	private UsmAccessDataService accessDataService;

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

	public void run() {
		accessDataService = new UsmAccessDataService();
		Calendar cal = Calendar.getInstance();
		if (!isRunning) {
			if (C_SCHEDULE_HOUR == cal.get(Calendar.HOUR_OF_DAY) && flag) {
				isRunning = true;
				// accessDataService.SendHttpByMonth(0,0, 0);
				System.out.println("正在执行任务");
				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;
		}
	}
}

3，web.xml中的配置

  
    com.annlee.website.util.TimerListener