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发表于: IP:您无权察看 2013-3-18 10:07:31 | [全部帖] [楼主帖] 楼主

    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




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