JMS QueueBrowser Example

This example shows you how to use a JMS QueueBrowser with ActiveMQ.
Queues are a standard part of JMS, please consult the JMS 1.1 specification for full details.
A QueueBrowser is used to look at messages on the queue without removing them. It can scan the entire content of a queue or only messages matching a message selector.

The example will send 2 messages on a queue, use a QueueBrowser to browse the queue (looking at the message without removing them) and finally consume the 2 messages

Example step-by-step

To run the example, simply type mvn verify -Pexample from this directory

1. First we need to get an initial context so we can look-up the JMS connection factory and destination objects from JNDI. This initial context will get it's properties from the client-jndi.properties file in the directory ../common/config

           InitialContext initialContext = getContext();
        

2. We look up the JMS queue object from JNDI

           Queue queue = (Queue) initialContext.lookup("/queue/exampleQueue");
        

3. We look up the JMS connection factory object from JNDI

           ConnectionFactory cf = (ConnectionFactory) initialContext.lookup("/ConnectionFactory");
        

4. We create a JMS connection

           connection = cf.createConnection();
        

5. We create a JMS session. The session is created as non transacted and will auto acknowledge messages.

           Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        

6. We create a JMS message producer on the session. This will be used to send the messages.

          MessageProducer messageProducer = session.createProducer(topic);
       

7. We create 2 JMS text messages that we are going to send.

            TextMessage message_1 = session.createTextMessage("this is the 1st message");
            TextMessage message_2 = session.createTextMessage("this is the 2nd message");
        

8. We send messages to the queue

           messageProducer.send(message_1);
           messageProducer.send(message_2);
        

9. We create a JMS QueueBrowser.
   We have not specified a message selector so the browser will enumerate the entire content of the queue.

           QueueBrowser browser = session.createBrowser(queue);
        

10. We browse the queue and display all the messages' text

            Enumeration messageEnum = browser.getEnumeration();
            while (messageEnum.hasMoreElements())
            {
               TextMessage message = (TextMessage)messageEnum.nextElement();
               System.out.println("Browsing: " + message.getText());
            }
        

11. We close the browser once we have finished to use it

            browser.close();
        

The messages were browsed but they were not removed from the queue. We will now consume them.

12. We create a JMS Message Consumer to receive the messages.

           MessageConsumer messageConsumer = session.createConsumer(queue);
        

13. We start the connection. In order for delivery to occur on any consumers or subscribers on a connection, the connection must be started

           connection.start();
        

14. The 2 messages arrive at the consumer

           TextMessage messageReceived = (TextMessage)messageConsumer.receive(5000);
           System.out.println("Received message: " + messageReceived.getText());
           messageReceived = (TextMessage)messageConsumer.receive(5000);
           System.out.println("Received message: " + messageReceived.getText());
        

15. And finally, always remember to close your JMS connections and resources after use, in a finally block. Closing a JMS connection will automatically close all of its sessions, consumers, producer and browser objects

           finally
           {
              if (initialContext != null)
              {
                initialContext.close();
              }
              if (connection != null)
              {
                 connection.close();
              }
           }