分两步走: (1). 实现 javax.servlet.ServletContextListener 接口的两个方法:contextInitialized()和contextDestroyed() contextInitialized():当Servlet容器启动时会执行 contextDestroyed():当Servlet容器停止时会执行 (2). 在contextInitialized()中加入需要监听的程序,并由 java.util.Timer 的 schedule() 方法来控制监听程序执行的频率 DEMO(这是我的一个短信回复监听的程序原型,精简了一下) ---------------------------------------------------------------- ReplyListener.java ---------------------------------------------------------------- package com.hanweb.jcms; import javax.servlet.*; public class ReplyListener implements ServletContextListener { private ReplyTimer rt = null; public void contextInitialized(ServletContextEvent event) { String status = "[SYS] SMS reply listener start ."; event.getServletContext().log(status); System.out.println(status); rt = new ReplyTimer(1); rt.start(); } public void contextDestroyed(ServletContextEvent event) { String status = "[SYS] SMS reply listener stop ."; event.getServletContext().log(status); System.out.println(status); if (rt != null) { rt.stop(); } } } ---------------------------------------------------------------- ReplyTimer.java ---------------------------------------------------------------- package com.hanweb.jcms; import java.util.*; public class ReplyTimer { private final Timer timer = new Timer(); private final int min; public ReplyTimer(int minutes) { min = minutes; } public void start() { Date date = new Date(); timer.schedule(new ReplyTask(), date, min * 60 * 1000); } public void stop() { timer.cancel(); } } ---------------------------------------------------------------- ReplyTask.java ---------------------------------------------------------------- package com.hanweb.jcms; import java.util.*; public class ReplyTask extends TimerTask { public void doSomething() { System.out.println("[SYS] SMS reply listener running "); } public void run() { doSomething(); } } 将编译好的class文件放入WEB-INF/classes中,最后别忘记了在Servlet容器中当前WEB应用的web.xml中加入监听语句: com.hanweb.jcms.ReplyListener |