EnterpriseJavaBeansDistilled...
2007-12-23 12:27:42 来源:WEB开发网核心提示:消息驱动bean(续)jms 应用客户程序to get a better idea of how JMS is used, we can create a java application whose sole purpose is receiving and PRocessing reservation messag
消息驱动bean(续)
jms 应用客户程序
to get a better idea of how JMS is used, we can create a java application whose sole purpose is receiving and PRocessing reservation messages. We will develop a very simple JMS client that simply prints a description of each ticket as it receives the messages. We'll assume that the TravelAgent EJB is using the TextMessage to send a description of the ticket to the JMS clients. The following code shows how the JMS application client might look:
为更好的理解如何使用JMS,可以开发一个Java应用,其唯一的用途在于接收和处理预定消息。在这里,将开发一个非常简单的JMS客户。当该客户接收到消息时,会打印出所每张票的描述信息。假定TravelAgent EJB使用TextMessage以发送票的描述给JMS客户。下列代码显示了JMS应用客户可能的样子:
JmsClient_1的构建器含有来自JNDI InitialContext的TopicConnectionFactory和Topic。这些对象是使用具体厂商产品的properties创建的,从而使得客户能够连接到TravelAgent EJB使用的同一JMS供应者。比如,WebLogic应用服务器中getInitialContext()方法的代码如下:(JNDI也允许将properties放置在jndi.properties文件中,该文件包含有用于InitialContext的property值,并能够在运行时被动态找到。本书中,显式的给出了properties值。)
一旦客户获得了TopicConnectionFactory和Topic,就可以采取和TravelAgent EJB相同的方式创建TopicConnection和TopicSession。它们的主要区别在于这里的TopicSession对象创建了TopicSubscriber对象,而不是TopicPublisher。其中,TopicSubscriber被明确设计成处理来自特定Topic的消息:
TopicSubscriber能直接接收消息,或者能够将消息的处理委派给接口javax.jms.MessageLister。在例子中,JmsClient_1实现了MessageListener接口,使得它可以处理消息。MessageListener对象实现了单一的方法,onMessage(),每当新消息发送到订阅者的topic中时,该方法都会被调用。在这里,每次TravelAgent EJB发送预定消息到topic中时,JMS客户中的onMessage()方法都会被调用,使得它能够接收到消息的拷贝并处理它:
待续。。。。。。。。
bill-转自:csdn进入讨论组讨论。
jms 应用客户程序
to get a better idea of how JMS is used, we can create a java application whose sole purpose is receiving and PRocessing reservation messages. We will develop a very simple JMS client that simply prints a description of each ticket as it receives the messages. We'll assume that the TravelAgent EJB is using the TextMessage to send a description of the ticket to the JMS clients. The following code shows how the JMS application client might look:
为更好的理解如何使用JMS,可以开发一个Java应用,其唯一的用途在于接收和处理预定消息。在这里,将开发一个非常简单的JMS客户。当该客户接收到消息时,会打印出所每张票的描述信息。假定TravelAgent EJB使用TextMessage以发送票的描述给JMS客户。下列代码显示了JMS应用客户可能的样子:
import javax.jms.Message;
import javax.jms.TextMessage;
import javax.jms.TopicConnectionFactory;
import javax.jms.TopicConnection;
import javax.jms.Topicsession;
import javax.jms.Topic;
import javax.jms.Session;
import javax.jms.TopicSubscriber;
import javax.jms.JMSException;
import javax.naming.InitialContext;
public class JmsClient_1 implements javax.jms.MessageListener {
public static void main(String[]args) throws Exception {
if(args.length != 2)
throw new Exception("Wrong number of arguments");
new JmsClient_1(args[0], args[1]);
while(true){Thread.sleep(10000);}
}
public JmsClient_1(String factoryName, String topicName) throws Exception {
InitialContext jndiContext = getInitialContext();
TopicConnectionFactory factory = (TopicConnectionFactory)
jndiContext.lookup("TopicFactoryNameGoesHere");
Topic topic = (Topic)jndiContext.lookup("TopicNameGoesHere");
TopicConnection connect = factory.createTopicConnection();
TopicSession session =
connect.createTopicSession(false,Session.AUTO_ACKNOWLEDGE);
TopicSubscriber subscriber = session.createSubscriber(topic);
subscriber.setMessageListener(this);
connect.start();
}
public void onMessage(Message message) {
try {
TextMessage textMsg = (TextMessage)message;
String text = textMsg.getText();
System.out.println("\n RESERVATION RECIEVED:\n"+text);
} catch(JMSException jmsE) {
jmsE.printStackTrace();
}
}
public static InitialContext getInitialContext() {
// 创建具体产品厂商的JNDI上下文
}
}
JmsClient_1的构建器含有来自JNDI InitialContext的TopicConnectionFactory和Topic。这些对象是使用具体厂商产品的properties创建的,从而使得客户能够连接到TravelAgent EJB使用的同一JMS供应者。比如,WebLogic应用服务器中getInitialContext()方法的代码如下:(JNDI也允许将properties放置在jndi.properties文件中,该文件包含有用于InitialContext的property值,并能够在运行时被动态找到。本书中,显式的给出了properties值。)
public static InitialContext getInitialContext() {
Properties env = new Properties();
env.put(Context.SECURITY_PRINCIPAL, "guest");
env.put(Context.SECURITY_CREDENTIALS, "guest");
env.put(Context.INITIAL_CONTEXT_FACTORY,
"weblogic.jndi.WLInitialContextFactory");
env.put(Context.PROVIDER_URL, "t3://localhost:7001");
return new InitialContext(env);
}
一旦客户获得了TopicConnectionFactory和Topic,就可以采取和TravelAgent EJB相同的方式创建TopicConnection和TopicSession。它们的主要区别在于这里的TopicSession对象创建了TopicSubscriber对象,而不是TopicPublisher。其中,TopicSubscriber被明确设计成处理来自特定Topic的消息:
TopicSession session =
connect.createTopicSession(false,Session.AUTO_ACKNOWLEDGE);
TopicSubscriber subscriber = session.createSubscriber(topic);
subscriber.setMessageListener(this);
connect.start();
TopicSubscriber能直接接收消息,或者能够将消息的处理委派给接口javax.jms.MessageLister。在例子中,JmsClient_1实现了MessageListener接口,使得它可以处理消息。MessageListener对象实现了单一的方法,onMessage(),每当新消息发送到订阅者的topic中时,该方法都会被调用。在这里,每次TravelAgent EJB发送预定消息到topic中时,JMS客户中的onMessage()方法都会被调用,使得它能够接收到消息的拷贝并处理它:
public void onMessage(Message message) {
try {
TextMessage textMsg = (TextMessage)message;
String text = textMsg.getText();
System.out.println("\n RESERVATION RECIEVED:\n"+text);
} catch(JMSException jmsE) {
jmsE.printStackTrace();
}
}
待续。。。。。。。。
bill-转自:csdn进入讨论组讨论。
(出处:http://www.cncms.com)
Tags:EnterpriseJavaBeansDistilled
编辑录入:爽爽 [复制链接] [打 印]- ››Enterprise-Wide Unique 标识符
- ››Enterprise JavaBeans组件慨述之一
- ››Enterprise JavaBeans 组件慨述之三
- ››EnterpriseJavaBean的结构优点的探讨
- ››Enterprise JavaBeans 基础知识简介
- ››Enterprise JavaBeans导论5
- ››Enterprise JavaBeans导论6
- ››Enterprise JavaBeans导论2
- ››Enterprise JavaBeans导论3
- ››Enterprise JavaBeans导论1
- ››Enterprise JavaBeans组件慨述之二
- ››Enterprise JavaBeans导论7
更多精彩
赞助商链接