I have a question about Message Driven Beans (MDB). Is there a way to generate these only at runtime? I want to provide a way in my backend to start or stop receiving messages. It should be controlled via a configuration entry in the database. When starting WildFly, it should also first check whether the MDBs can be started.
Is it Java EE compliant to do without an MDB and create the listeners manually?
I am currently using the following code
@MessageDriven(name = "MyMDB", activationConfig = {
@ActivationConfigProperty(propertyName = "maxSession", propertyValue = "2"),
@ActivationConfigProperty(propertyName = "destination", propertyValue = "java:/jms/queue/Test"),
@ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue"),
@ActivationConfigProperty(propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge")})
public class JmsConsumer implements MessageListener {
@Override
public void onMessage(final Message msg) {
if (msg instanceof TextMessage) {
try {
final String text = ((TextMessage) msg).getText();
System.out.println("message: " + text + " (" + msg.getJMSRedelivered() + ")");
} catch (final JMSException e) {
e.printStackTrace();
}
}
}
}
Would this code also conform to Java EE?
@Singleton
@LocalBean
public class QueueWorkerManager {
private InitialContext initialContext = null;
private QueueConnectionFactory queueConnectionFactory = null;
private Queue queue = null;
private QueueConnection queueConnection = null;
private QueueSession queueSession = null;
private MessageConsumer consumer = null;
@PostConstruct
public void init() {
try {
this.initialContext = new InitialContext();
this.queueConnectionFactory = (QueueConnectionFactory) initialContext
.lookup("java:/ConnectionFactory");
this.queue = (Queue) initialContext.lookup(MyQueueSender.WORKER_QUEUE);
this.queueConnection = queueConnectionFactory.createQueueConnection();
this.queueSession = queueConnection.createQueueSession(false, Session.CLIENT_ACKNOWLEDGE);
this.consumer = queueSession.createConsumer(this.queue);
this.consumer.setMessageListener(new ConsumerMessageListener());
this.queueConnection.start();
} catch (Exception ex) {
ex.printStackTrace();
}
}
@PreDestroy
public void destroy() {
this.stopConsumer(this.consumer;
if(this.consumer != null) {
try {
this.consumer.close();
} catch (JMSException e) {
}
this.consumer = null;
}
if(this.queueSession != null) {
try {
this.queueSession.close();
} catch (JMSException e) {
}
this.queueSession = null;
}
if(this.queueConnection != null) {
try {
this.queueConnection.close();
} catch (JMSException e) {
}
this.queueConnection = null;
}
}
}
public class ConsumerMessageListener implements MessageListener {
@Override
public void onMessage(Message message) {
TextMessage textMessage = (TextMessage) message;
try {
System.out.println("message: " + textMessage.getText() + " (" + msg.getJMSRedelivered() + ")");
message.acknowledge();
} catch (JMSException | InterruptedException e) {
e.printStackTrace();
}
}
}
