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之前接触过程序中的定时任务，但是没去自己亲自尝试过。终于这次抽空搞了一下。（一定要自己去操作，才能长经验，光看到过是没用的）

以下是两种方法，我使用的是监听的方法。

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。

一，继承HttpServlet的写法：

1，Servlet

1. 
   import
   
   java.io.IOException;
2. 
   import
   
   java.util.Timer;
3. 
   import
   
   javax.servlet.RequestDispatcher;
4. 
   import
   
   javax.servlet.ServletContext;
5. 
   import
   
   javax.servlet.ServletException;
6. 
   import
   
   javax.servlet.http.HttpServlet;
7. 
   import
   
   javax.servlet.http.HttpServletRequest;
8. 
   import
   
   javax.servlet.http.HttpServletResponse;
12. 
    public
    
    
    class
    
    ConvergeDataServlet
    
    extends
    
    HttpServlet {
14. 
    private
    
    
    static
    
    
    final
    
    
    long
    
    serialVersionUID = 1L;
16. 
    private
    
    Timer timer1 =
    
    null
    
    ;
18. 
    private
    
    Task task1;
20. 
    /**
    
21. 
    * Constructor of the object.
    
22. 
    */
    
23. 
    public
    
    ConvergeDataServlet() {
24. 
    super
    
    ();
25. }
27. 
    /**
    
28. 
    * Destruction of the servlet.
    
    
29. 
    */
    
30. 
    public
    
    
    void
    
    destroy() {
31. 
    super
    
    .destroy();
32. 
    if
    
    (timer1!=
    
    null
    
    ){
33. timer1.cancel();
34. }
35. }
38. 
    public
    
    
    void
    
    doGet(HttpServletRequest request, HttpServletResponse response)
39. 
    throws
    
    ServletException, IOException {
41. }
44. 
    public
    
    
    void
    
    doPost(HttpServletRequest request, HttpServletResponse response)
45. 
    throws
    
    ServletException, IOException {
46. doGet(request, response);
47. }
49. 
    // init方法启动定时器
    
50. 
    public
    
    
    void
    
    init()
    
    throws
    
    ServletException {
52. ServletContext context = getServletContext();
54. 
    // (true为用定时间刷新缓存)
    
55. String startTask = getInitParameter(
    
    “startTask”
    
    );
57. 
    // 定时刷新时间(分钟)
    
58. Long delay = Long.parseLong(getInitParameter(
    
    “delay”
    
    ));
60. 
    // 启动定时器
    
61. 
    if
    
    (startTask.equals(
    
    “true”
    
    )){
62. timer1 =
    
    new
    
    Timer(
    
    true
    
    );
63. task1 =
    
    new
    
    Task(context);
64. timer1.schedule(task1, delay *
    
    60
    
    *
    
    1000
    
    , delay *
    
    60
    
    *
    
    1000
    
    );
65. }
66. }
67. }

2，任务

2. import java.util.TimerTask;
5. import javax.servlet.ServletContext;
7. public class Task extends TimerTask{
9. private ServletContext context;
11. private static boolean isRunning = true;
13. public Task(ServletContext context){
14. this.context = context;
15. }
18. @Override
19. public void run() {
20. if(isRunning){
22. }
23. }
25. }

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;

public AnnleeTimerTask(ServletContext context){


this.context = context;

}

public void run() {

//你要执行的操作

}

}

3，web.xml中的配置

<listener>

<listener-class>

com.annlee.website.util.TimerListener

</listener-class>

</listener>