J2EE----JMS

1、JMS是一个由AS提供的Message服务。它能接受消息产生者(Message Provider)所发出的消息，并把消息转发给消息消费者(Message  Consumer)。

2、JMS提供2种类型的消息服务：(1)Queue，即点对点，每个消息只转发给一个消息消费者使用。(2)Topic，即发布和订阅，每个消息可以转发给所有的订阅者(消费者)。

3、jboss下的JMS配置：

  (1)配置JMS Connection Factory
  (2)配置JMS File Store
  (3)配置JMS Server
  (4)在JMS Server的destinations中配置JMS Queue或者JMS Topic
其中提供给消息产生者和消息消费者使用的是JMS Connection Factory的JNDI和JMS Queue或者JMS Topic的JNDI。

4、消息产生者向JMS发送消息的步骤：

(1)使用JNDI查询对象JMS ConnectionFactory和Destination(JMS Queue/Topic)
(2)使用管理对象JMS ConnectionFactory建立连接Connection
(3)使用连接Connection 建立会话Session
(4)使用会话Session和管理对象Destination创建消息生产者MessageSender
(5)使用消息生产者MessageSender发送消息
一个消息发送者的例子：

package myjms;
import java.util.*;
import javax.naming.*;
import javax.jms.*;
public class MessageProducter {
  public static void main(String[] args) {
    String queueConnectionFactoryName = "myjmsconnectionfactory"; //JMS Connection Factory的JNDI
    String queueName = "myjmsqueue"; //JMS Queue或者JMS Topic的JNDI
    boolean transacted = false;//transaction模式
    int acknowledgementMode = Session.AUTO_ACKNOWLEDGE;//acknowledgement模式
    String message="Message need to send";//模拟需要发送的消息
    Properties properties = new Properties();
    properties.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory");
    properties.put(Context.PROVIDER_URL, "t3://localhost:7001");
    try {
      Context context = new InitialContext(properties);
      Object obj = context.lookup(queueConnectionFactoryName);
      QueueConnectionFactory queueConnectionFactory = (QueueConnectionFactory) obj;//JMS Connection Factory的获得
     
      obj = context.lookup(queueName);
      Queue queue = (Queue) obj;//JMS Queue或者JMS Topic的获得
      QueueConnection queueConnection=queueConnectionFactory.createQueueConnection();//产生连接
      queueConnection.start();
      QueueSession queueSession = queueConnection.createQueueSession(transacted, acknowledgementMode);
      TextMessage textMessage = queueSession.createTextMessage();
      textMessage.clearBody();
      textMessage.setText(message);
      QueueSender queueSender = queueSession.createSender(queue);
      queueSender.send(textMessage);
      if (transacted) {
        queueSession.commit();
      }
      if (queueSender != null) {
        queueSender.close();
      }
      if (queueSession != null) {
        queueSession.close();
      }
      if (queueConnection != null) {
        queueConnection.close();
      }
    }
    catch(Exception ex){
      ex.printStackTrace();
    }
  }
}

5、消息消费者从JMS接受消息的步骤：

(1)使用JNDI查询对象JMS ConnectionFactory和Destination(JMS Queue/Topic)
(2)使用管理对象JMS ConnectionFactory建立连接Connection
(3)使用连接Connection 建立会话Session
(4)使用会话Session和管理对象Destination创建消息消费者MessageReceiver
(5)使用消息消费者MessageReceiver接受消息，需要用setMessageListener将MessageListener接口绑定到MessageReceiver
消息消费者必须实现了MessageListener接口，需要定义onMessage事件方法。
一个消息消费者的例子：

package myjms;
import java.util.*;
import javax.naming.*;
import javax.jms.*;
public class MessageReciever
    implements MessageListener {
  public void onMessage(Message message) {
    if (message instanceof TextMessage) {
      TextMessage textMessage = (TextMessage) message;
      try {
        System.out.println("Message content is:" + textMessage.getText());
      }
      catch (JMSException e) {
        e.printStackTrace();
      }
    }
  }
  public static void main(String[] args) {
   
    MessageReciever msgRcvr=new MessageReciever();
    String queueConnectionFactoryName = "myjmsconnectionfactory";
    String queueName = "myjmsqueue";
    boolean transacted = false;
    int acknowledgementMode = Session.AUTO_ACKNOWLEDGE;
    Properties properties = new Properties();
    properties.put(Context.INITIAL_CONTEXT_FACTORY,
                   "weblogic.jndi.WLInitialContextFactory");
    properties.put(Context.PROVIDER_URL, "t3://localhost:7001");
    try {
      Context context = new InitialContext(properties);
      Object obj = context.lookup(queueConnectionFactoryName);
      QueueConnectionFactory queueConnectionFactory = (QueueConnectionFactory)
          obj;
      obj = context.lookup(queueName);
      Queue queue = (Queue) obj;
      QueueConnection queueConnection = queueConnectionFactory.
          createQueueConnection();
      queueConnection.start();
      QueueSession queueSession = queueConnection.createQueueSession(transacted,
          acknowledgementMode);
      QueueReceiver queueReceiver = queueSession.createReceiver(queue);
      queueReceiver.setMessageListener(msgRcvr);
      synchronized(msgRcvr){
        msgRcvr.wait(100000);
      }
      if (queueReceiver != null) {
        queueReceiver.close();
      }
      if (queueSession != null) {
        queueSession.close();
      }
      if (queueConnection != null) {
        queueConnection.close();
      }
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }
  }
}