JavaWeb如何设置定时任务

比眉伴天荒 2021-12-11 06:05 179阅读 0赞

1.在xml文件中添加监听器

<?xml version="1.0" encoding="UTF-8"?>
    <web-app 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">
     <listener>
      <listener-class>com.tct.test.ContextListener</listener-class>
     </listener>
    </web-app>

2.编写定时任务Java代码

package com.tct.test;  
    
        import java.util.Timer;  
    
        import javax.servlet.ServletContextEvent;  
        import javax.servlet.ServletContextListener;  
    
        public class ContextListener implements ServletContextListener {  
            Timer timer = new Timer() ;  
    
           public void contextInitialized(ServletContextEvent event) {  
               timer = new java.util.Timer(true);   
    
    
               event.getServletContext().log("定时器已启动");           
    
                timer.schedule(new MyTask(event.getServletContext()), 0,1000);   
    
               event.getServletContext().log("已经添加任务调度表");   
    
    
           }  
    
           public void contextDestroyed(ServletContextEvent event) {  
    
               timer.cancel();  
    
               event.getServletContext().log("定时器以销毁");  
           }  
    
       }  
    
       package com.tct.test;  
    
       import java.util.TimerTask;  
    
       import javax.servlet.ServletContext;  
    
       public class MyTask extends TimerTask {  
           private static boolean isRunning = false;   
           private ServletContext context = null;   
           public MyTask(ServletContext servletContext) {  
               this.context = servletContext;  
           }  
           @Override  
           public void run() {  
             if(!isRunning)  
             {  
               isRunning = true;  
               context.log("开始执行指定任务");   
               isRunning = false;  
             }  
             else  
             {  
                 context.log("上次的任务还未执行完成");  
             }  
           }  
       }