在EJB3中，一個MDB（消息驅(qū)動Bean）就是一個實(shí)現(xiàn)了MessageListener接口的POJO。下面就是一個簡單的MDB。
@MessageDriven(activationConfig={
        @ActivationConfigProperty(propertyName="destinationType",
                propertyValue="javax.jms.Queue"),
        @ActivationConfigProperty(propertyName="destination",
                propertyValue="queue/testQueue")})
public class SimpleMDB implements MessageListener {
   
    public void onMessage(Message message) {
        try {
            System.out.println("Receive Message : " + ((TextMessage)message).getText());
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }
}

它要求必須標(biāo)注為@MessageDriven。它所監(jiān)聽Destination通過標(biāo)注屬性來注入。

下面是一個發(fā)送消息的StatelessBean：
@Remote
public interface IMessageSender {
    public void sendMessage(String content) throws Exception;
}


@Stateless
@Remote
public class MessageSender implements IMessageSender {
    @Resource(mappedName="ConnectionFactory")
    private ConnectionFactory factory;
   
    @Resource(mappedName="queue/testQueue")
    private Queue queue;
   
   
    public void sendMessage(String content) throws Exception {
        Connection cn = factory.createConnection();
       
        Session session = cn.createSession(false, Session.AUTO_ACKNOWLEDGE);
        MessageProducer producer = session.createProducer(queue);
        producer.send(session.createTextMessage(content));
    }
}
這個EJB只有一個方法SendMessage。ConnectionFactory和Queue通過標(biāo)注注入。

接下來是客戶端：
public class MessageSenderClient {
    public static void main(String[] args) throws Exception {
        Properties props = new Properties();
        props.setProperty(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
        props.setProperty(Context.PROVIDER_URL, "localhost:2099");
        Context context = new InitialContext(props);
        IMessageSender messageSender = (IMessageSender) context.lookup("MessageSender/remote");
        messageSender.sendMessage("Hello");
    }
}
它通過JNDI查找到上面的EJB，然后調(diào)用sengMessage.