定时器tasktimer

1、web.xml中配置

<servlet> 
<servlet-name>TaskTimer</servlet-name> 
<servlet-class>com.XXXXX.controller.TaskTimer</servlet-class> 
<load-on-startup>2</load-on-startup> 
</servlet>

2、写实现方法

package com.XXX.controller;

import java.util.Date;
import java.util.Timer;  
import java.util.TimerTask;

import javax.servlet.http.HttpServlet;

public class TaskTimer extends HttpServlet{
    
    private static final long serialVersionUID = 1L;

    public void init(){
        Timer timer = new Timer();    
        timer.schedule(new TimerTask() {    
            public void run() {    
                System.out.println(new Date()+"-----Hello !!!");
            }    
        }, 1000*5, 1000*3);//第二个参数为多少毫秒后启动，第三个参数为每个多少毫秒执行一次
    }
}

 若在TaskTimer中调用service，用@Autowired注入，启动项目会报空指针错误，原因及分析可查看此文档

因此对代码进行修改

package com.XXXX.controller;

import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Timer;  
import java.util.TimerTask;

import javax.servlet.ServletContextEvent;
import javax.servlet.http.HttpServlet;

import org.springframework.stereotype.Controller;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

@Controller
public class TaskTimer extends HttpServlet{
    private static final long serialVersionUID = 1L;

    public void init(){
        final ServletContextEvent sce = new ServletContextEvent(getServletContext());
        
        Timer timer = new Timer();
        timer.schedule(new TimerTask() {
            //获得Spring容器
            WebApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(sce.getServletContext());
            //从Spring容器中获得SelectDataServlet的实例
            private Service service = ctx.getBean(service.class);public void run() {
                System.out.println("已经开始跑定时器");
　　　　　　　　　　//定时器主体，此处可调用service实体

            }
        }, 1000*5, 1000*60*60*24);
    }
}