Example usage for javax.jms MapMessage itemExists

Introduction

In this page you can find the example usage for javax.jms MapMessage itemExists.

Prototype

boolean itemExists(String name) throws JMSException;

Source Link

Document

Indicates whether an item exists in this MapMessage object.

Usage

From source file:org.apache.james.queue.activemq.ActiveMQMailQueue.java

/**
 * Try to use ActiveMQ StatisticsPlugin to get size and if that fails
 * fallback to {@link JMSMailQueue#getSize()}
 *//* www  .  ja v  a 2s .  co  m*/
@Override
public long getSize() throws MailQueueException {

    Connection connection = null;
    Session session = null;
    MessageConsumer consumer = null;
    MessageProducer producer = null;
    TemporaryQueue replyTo = null;
    long size = -1;

    try {
        connection = connectionFactory.createConnection();
        connection.start();

        session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        replyTo = session.createTemporaryQueue();
        consumer = session.createConsumer(replyTo);

        Queue myQueue = session.createQueue(queuename);
        producer = session.createProducer(null);

        String queueName = "ActiveMQ.Statistics.Destination." + myQueue.getQueueName();
        Queue query = session.createQueue(queueName);

        Message msg = session.createMessage();
        msg.setJMSReplyTo(replyTo);
        producer.send(query, msg);
        MapMessage reply = (MapMessage) consumer.receive(2000);
        if (reply != null && reply.itemExists("size")) {
            try {
                size = reply.getLong("size");
                return size;
            } catch (NumberFormatException e) {
                // if we hit this we can't calculate the size so just catch
                // it
            }
        }

    } catch (Exception e) {
        throw new MailQueueException("Unable to remove mails", e);

    } finally {

        if (consumer != null) {

            try {
                consumer.close();
            } catch (JMSException e1) {
                e1.printStackTrace();
                // ignore on rollback
            }
        }

        if (producer != null) {

            try {
                producer.close();
            } catch (JMSException e1) {
                // ignore on rollback
            }
        }

        if (replyTo != null) {
            try {

                // we need to delete the temporary queue to be sure we will
                // free up memory if thats not done and a pool is used
                // its possible that we will register a new mbean in jmx for
                // every TemporaryQueue which will never get unregistered
                replyTo.delete();
            } catch (JMSException e) {
            }
        }
        try {
            if (session != null)
                session.close();
        } catch (JMSException e1) {
            // ignore here
        }

        try {
            if (connection != null)
                connection.close();
        } catch (JMSException e1) {
            // ignore here
        }
    }

    // if we came to this point we should just fallback to super method
    return super.getSize();
}

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