A simple method of implementing timing task with Java in Web application

A simple method to implement timed tasks under Web application

In Web mode, if we want to implement certain tasks on a regular basis, in addition to using quartz and other third-party open source tools, we can use timer and Timetask to complete the specified timing tasks:

The first step: Create a task management class, implement Servletcontextlistener interface

The following is a reference fragment:

public class TaskManager implements ServletContextListener {
/**
　* 每天的毫秒数
　*/
public static final long PERIOD_DAY = DateUtils.MILLIS_IN_DAY;
/**
　* 一周内的毫秒数
　*/
public static final long PERIOD_WEEK = PERIOD_DAY * 7;
/**
　* 无延迟
　*/
public static final long NO_DELAY = 0;
/**
　* 定时器
　*/
private Timer timer;
/**
　* 在Web应用启动时初始化任务
　*/
public void contextInitialized(ServletContextEvent event) {
　　　　//定义定时器
　timer = new Timer("数据库表备份",true);
　//启动备份任务,每月(4个星期)执行一次
　timer.schedule(new BackUpTableTask(),NO_DELAY, PERIOD_WEEK * 4);
//　timer.schedule(new BackUpTableTask(),NO_DELAY, 30000);
}
/**
　* 在Web应用结束时停止任务
　*/
public void contextDestroyed(ServletContextEvent event) {
　timer.cancel(); // 定时器销毁
}
}

Step Two: Create a Time task class

The following is a reference fragment:

public class BackUpTableTask extends TimerTask {
private static Log log = LogFactory.getLog(BackUpTableTask.class);
private static boolean isRunning = false;
public void run() {
　if (!isRunning) {
　 isRunning = true;
　 log.debug("开始执行任务..."); //开始任务
　 //working　add what you want to do
　 log.debug("执行任务完成..."); //任务完成
　 isRunning = false;
　} else {
　 log.debug("上一次任务执行还未结束..."); //上一次任务执行还未结束
　}
}
}

Step three: Add a listener to the web

The following is a reference fragment:

<listener>
　<listener-class>***.TaskManager</listener-class>
　<description>要定期执行的任务</description>
</listener>

When the Web server is started, the task is also started and periodically executed.