Java Web监听器如何实现定时发送邮件

package com.sun.action;
 
import java.util.Timer;
 
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
 
/**
 * @author szy
 * @version 创建时间：2018-4-5 上午10:46:11
 *
 */
public class MyTimerTask implements ServletContextListener {
 
  private Timer timer = null;
  @Override
  public void contextDestroyed(ServletContextEvent event) {
    // TODO Auto-generated method stub
 
    timer.cancel();
     event.getServletContext().log("定时器销毁");
     
  }
 
  @Override
  public void contextInitialized(ServletContextEvent event) {
    // TODO Auto-generated method stub
 
    //在这里初始化监听器，在tomcat启动的时候监听器启动，可以在这里实现定时器功能
     timer = new Timer(true);
     event.getServletContext().log("定时器已启动");//添加日志，可在tomcat日志中查看到
     //调用exportHistoryBean，0表示任务无延迟，5*1000表示每隔5秒执行任务，60*60*1000表示一个小时；
     //timer.schedule(new SendEmail(event.getServletContext()),0,24*60*60*1000);
     timer.schedule(new SendEmail(event.getServletContext()),0,5*1000);
  }
}

package com.sun.action;
 
import java.util.TimerTask;
 
import javax.servlet.ServletContext;
 
/**
 * @author szy
 * @version 创建时间：2018-4-5 上午10:50:00
 *
 */
public class SendEmail extends TimerTask {
 
  private ServletContext context = null;
  public SendEmail(ServletContext context)
  {
   this.context = context;
  }
   
  @Override
  public void run() {
    // TODO Auto-generated method stub
    System.out.println("您的邮件已发送，清注意查收");
  }
 
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
 <display-name>TimerWeb</display-name>
 <welcome-file-list>
  <welcome-file>index.html</welcome-file>
  <welcome-file>index.htm</welcome-file>
  <welcome-file>index.jsp</welcome-file>
  <welcome-file>default.html</welcome-file>
  <welcome-file>default.htm</welcome-file>
  <welcome-file>default.jsp</welcome-file>
 </welcome-file-list>
 <listener>
  <listener-class>com.sun.action.MyTimerTask</listener-class>
 </listener>
</web-app>