Java定时器在Web中的应用（2）

在web中,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，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,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

java 代码

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;   
  
import org.apache.commons.lang.StringUtils;   
  
public class ConvergeDataServlet extends HttpServlet {   
  
    private static final long serialVersionUID = 1L;   
  
    private Timer timer1 = null;   
       
    private Task task1;   
       
      
    public ConvergeDataServlet() {   
        super();   
    }   
  
      
    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);   
        }   
    }   
}

 定时执行操作

java 代码

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){   
             
        }   
    }
}   

在web.xml配置这个servlet为服务启动时就调用servlet

<servlet></servlet>
  <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>
<servlet></servlet>

 

引自：http://blog.sina.com.cn/s/blog_6231c6540100mjhu.html