Eclipse中的Java EE项目文件夹结构？

Question

I am new to Java EE programming. I am attempting to write a JMS sender in Eclipse using Java EE. I have created a new Java EE project and now my doubt is what is the folder structure and where to write my JMS sender java file.

I am using JBoss AS. My requirement is that I have to push the messages to a JMS Queue using this JMS sender application.

Answer 1

First of all you need to write a MDB ( Message driven bean) to consume your JMS messages. For clarity purposes i will present a small example;

@MessageDriven(activationConfig = {
    @ActivationConfigProperty(propertyName = "destinationType", propertyValue =   "javax.jms.Queue"),
    @ActivationConfigProperty(propertyName = "destination", propertyValue = "queue/offlinemsg"),
    @ActivationConfigProperty(propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge") })
@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
public class MessageHandlerMDB implements MessageListener {

private static final Logger log = Logger.getLogger(MessageHandlerMDB.class);


@Override
public void onMessage(Message message) {

    log.info("Message received in MessageHandlerMDB");


}

}

On deployment of your app the server will identify the message driven bean based on the annotations and create a queue for you. You can then send message to this queue as usual through a ConnectionFactory. If you are sending a message through the same application within Jboss then you can write as follows;

 private void sendObjectToQueue(Serializable object) {


    Session session = null;
    MessageProducer sender = null;
    Connection connect = null;

    if (logger.isDebugEnabled()) {
    logger.debug("Entered sendObjectToQueue(" + object.getClass());
    }

    try {

        Context context = new InitialContext();
        ConnectionFactory factory = (ConnectionFactory) context
                .lookup("ConnectionFactory");

        Queue queue = (Queue) context.lookup("queue/offlinemsg");
        connect = factory.createConnection();
        session = connect.createSession(false,
                Session.AUTO_ACKNOWLEDGE);
        sender = session.createProducer(queue);

        ObjectMessage message = session.createObjectMessage();

        message.setObject(object);
        sender.send(message);
        sender.close();
        connect.close();

        if (logger.isDebugEnabled()) {
        logger.debug("The " + object.getClass() + " object was sent to jms queue");
        }

    } catch (JMSException e) {
        logger.error("Sending object to queue failed", e);


    } catch (Exception e) {
        logger.error("Sending object to queue failed", e);


    } finally {

        if (sender != null) {
            try {
                sender.close();
                if (logger.isDebugEnabled()) {
                    logger.debug("Closed jms session");
                }
            } catch (JMSException e) {
                logger.error("Closing jms session failed", e);
            }
        }

        if (connect != null) {
            try {
                connect.close();
                if (logger.isDebugEnabled()) {
                    logger.debug("Closed jms session");
                }
            } catch (Exception e) {
                logger.error("Closing jms session failed", e);
            }
        }

        if (session != null) {
            try {
                session.close();
                if (logger.isDebugEnabled()) {
                    logger.debug("Closed jms session");
                }
            } catch (Exception e) {
                logger.error("Closing jms session failed", e);
            }
        }
    }
}

Let me know if you need further clarification. Hope this helps.

Edited *

If you are calling from a normal java class then following code is required(note that this is specific to JBoss)

Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
env.put(Context.PROVIDER_URL, "jnp://localhost:1099");
env.put(Context.URL_PKG_PREFIXES, "org.jboss.naming:org.jnp.interfaces");

Context ctx = new InitialContext(env);
ConnectionFactory cf = (ConnectionFactory)ctx.lookup("/ConnectionFactory");
Queue queue = (Queue)ic.lookup("/queues/MyQueue");
Connection connection = cf.createConnection();
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
MessageProducer producer = session.createProducer(queue);
connection.start();
TextMessage message = session.createTextMessage("Test");
producer.send(message);

Note that you should reuse the Connection creation and session creation as best practices...