java 定时 发送 信息类似于闹钟

package a; import java.text.ParseException; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; public class ReplyListener implements ServletContextListener { private ReplyTimer t=null; public void contextDestroyed(ServletContextEvent arg0) { t.stop(); } public void contextInitialized(ServletContextEvent arg0) { t=new ReplyTimer(); try { t.start(); } catch (ParseException e) { e.printStackTrace(); } } }