WebLogic Server包含了Timer Service功能，你可以指定某一时刻或某一时间间隔产生Timer事件，同时你可以使用委托代理的机制，为这个事件注册事件监听器，以实现Timer Service功能。

　　从WebLogic Server 7.0以后的版本，WebLogic Timer Service扩展自标准的JMX Timer Service，使其可以运行于WebLogic Server的执行线程中，并且享有WebLogic Server的安全上下文环境，也就是说，可以在代码中得到安全信息，如用户名等。下面结合一个实例演示其功能。

File:TimerServiceListener.java

package org.yekki.weblogic.timer;

import java.util.Date;

import java.util.Random;

import javax.jms.JMSException;

import javax.jms.Queue;

import javax.jms.QueueConnection;

import javax.jms.QueueConnectionFactory;

import javax.jms.QueueSender;

import javax.jms.QueueSession;

import javax.jms.Session;

import javax.jms.TextMessage;

import javax.management.InstanceNotFoundException;

import javax.management.Notification;

import javax.management.NotificationListener;

import javax.naming.Context;

import javax.naming.InitialContext;

import javax.servlet.ServletContext;

import javax.servlet.ServletContextEvent;

import javax.servlet.ServletContextListener;

import org.apache.ecs.xml.XML;

import weblogic.management.timer.Timer;

public class TimerServiceListener

       implements ServletContextListener, NotificationListener {

       private long period;

       private boolean debug;

       private Timer timer;

       private Integer notificationId;

       private QueueConnectionFactory factory;

       private QueueConnection connection;

       private QueueSession session;

       private QueueSender sender;

       private Queue queue;

       private Context ctx;

       public void contextInitialized(ServletContextEvent event) {

              initParams(event);

              initJMS();

              debug(">>> contextInitialized called.");

              timer = new Timer();

              timer.addNotificationListener(this, null, "Message Broker ");

              Date timerTriggerAt = new Date((new Date()).getTime() + 5000L);

              notificationId =

                     timer.addNotification(

                            "Timer Type",

                            "Timer Message",

                            this,

                            timerTriggerAt,

                            period);

              timer.start();

              debug(">>> timer started.");

              printBrief();

       }

       public void initParams(ServletContextEvent event) {

              ServletContext ctx = event.getServletContext();

              try {

                     debug = Boolean.valueOf((String)ctx.getInitParameter("debug")).booleanValue();

              }

              catch (Exception e) {

                     debug = false;

                     e.printStackTrace();

              }

              try {

                     /*

                      second:1000L

                      minute:60000L

                      hour:3600000L

                      day:86400000L

                      week:604800000L

                      */

                     period =

                            Long

                                   .valueOf((String)ctx.getInitParameter("period"))

                                   .longValue();

              }

              catch (Exception e) {

                     period = Timer.ONE_MINUTE;

                     e.printStackTrace();

              }

              debug(">>> initialized application parameters.");

       }

       private void initJMS() {

              try {

                     ctx = new InitialContext();

                     factory =

                            (QueueConnectionFactory)ctx.lookup(

                                   "javax.jms.QueueConnectionFactory");

                     queue = (Queue)ctx.lookup("queue");

                     connection = factory.createQueueConnection();

                     session =

                            connection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);

                     sender = session.createSender(queue);

                     connection.start();

                     debug(">>> initialized jms.");

              }

              catch (Exception e) {

                     e.printStackTrace();

              }

       }

       public void sendMessage(String message) {

              try {

                     TextMessage msg = session.createTextMessage();

                     msg.setText(message);

                     sender.send(msg);

                     debug(">>> ################################");

                     debug("Send a message on " + new Date());

                     debug(message);

                     debug(">>> ################################");

              }

              catch (JMSException e) {

                     e.printStackTrace();

              }

       }

       public void contextDestroyed(ServletContextEvent event) {

              debug(">>> contextDestroyed called.");

              try {

                     timer.stop();

                     timer.removeNotification(notificationId);

                     debug(">>> timer stopped.");

              }

              catch (InstanceNotFoundException e) {

                     e.printStackTrace();

              }

              try {

                     if (session != null)

                            session.close();

                     if (connection != null)

                            connection.close();

                     debug(">>> closed jms connection and session.");

              }

              catch (JMSException e) {

                     e.printStackTrace();

              }

       }

       private void printBrief() {

              String d = "";

              d = debug ? "ON" : "OFF";

              print(">>> ################################");

              print(">>> Author: Niu Xiuyuan");

              print(">>> EMail: niuxiuyuan@bea.com.cn");

              print(">>> Company: BEA Systems");

              print("");

              print(">>> Debug: " + d);

              print(">>> Period: " + getPeriodInfo(period));

              print(">>> ################################");

       }

       private void print(String str) {

              System.out.println(str);

       }

       private String getPeriodInfo(long p) {

              if (p == Timer.ONE_DAY)

                     return "One Day";

              if (p == Timer.ONE_HOUR)

                     return "One Hour";

              if (p == Timer.ONE_MINUTE)

                     return "One Minute";

              if (p == Timer.ONE_SECOND)

                     return "One Second";

              if (p == Timer.ONE_WEEK)

                     return "One Week";

              return "Unsupported time period!! period=" + p;

       }

       public void handleNotification(Notification notif, Object handback) {

              Random rnd = new Random();

              sendMessage(genXML(rnd.nextInt(10)));

       }

       public String genXML(int id) {

              String username = "guru";

              String password = "niu986";

              XML usernameXML = null;

              XML idXML = null;

              XML passwordXML = null;

              XML userXML = null;

              XML profileXML = new XML("profiles");

              for (int i = 1; i <= id; i++) {

                     usernameXML = (new XML("user")).addElement(username);

                     idXML = (new XML("id")).addElement(Integer.toString(id));

                     passwordXML = (new XML("password")).addElement(password);

                     userXML =

                            (new XML("user"))

                                   .addXMLAttribute("age", "27")

                                   .addElement(idXML)

                                   .addElement(usernameXML)

                                   .addElement(passwordXML);

                     profileXML.addElement(userXML);

              }

              return profileXML.toString();

       }

       private void debug(String msg) {

              if (debug) {

                     System.out.println(msg);

              }

       }

       public static void main(String[] args) {

       }

}

　　说明：为了方便演示，此类中包含了事件产生器代码与事件监听器代码。使用ServletContextListener接口来控制Timer的启动与停止。

File:web.xml

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>

  <context-param>

    <param-name>debug</param-name>

    <param-value>false</param-value>

  </context-param>

  <context-param>

    <param-name>period</param-name>

    <param-value>60000</param-value>

  </context-param>

  <listener>

    <listener-class>org.yekki.weblogic.timer.TimerServiceListener</listener-class>

  </listener>

  <login-config>

    <auth-method></auth-method>

  </login-config>

</web-app>

　　说明：我们将webapp的Lisener注册，并且指定事件产生的时间间隔

    将此WebApp部署到WebLogic Server上，然后通过中端（例如：DOS窗口）查看实验结果。

　　附：本例中使用了Apache的ECS项目类库，您可以访问如下URL:

　　http://jakarta.apache.org/ecs/index.html