无法让ActiveMQ重新发送我的消息

Question

我有一个用Java编写的单线程ActiveMQ使用者.我要做的就是从队列中接收()一个消息,尝试将其发送到Web服务,如果成功则确认()它.如果Web服务调用失败,我希望消息保留在队列中并在超时后重新发送.

除了重新发送部分之外,它或多或少都在工作:每次重新启动我的消费者时,它会为仍然在队列中的每个消息收到一条消息,但是在发送它们之后,消息永远不会被重新发送.

我的代码看起来像:

public boolean init() throws JMSException, FileNotFoundException, IOException {
    ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory(user, password, url);
    RedeliveryPolicy policy = new RedeliveryPolicy();
    policy.setInitialRedeliveryDelay(500);
    policy.setBackOffMultiplier(2);
    policy.setUseExponentialBackOff(true);

    connectionFactory.setRedeliveryPolicy(policy);
    connectionFactory.setUseRetroactiveConsumer(true); // ????
    Connection connection = connectionFactory.createConnection();

    connection.setExceptionListener(this);
    connection.start();

    session = connection.createSession(transacted, ActiveMQSession.INDIVIDUAL_ACKNOWLEDGE);
    destination = session.createQueue(subject); //???

    consumer = session.createConsumer(destination);
    //consumer.setMessageListener(this); // message listener had same behaviour

}

private void process() {
    while(true) {
        System.out.println("Waiting...");
        try {
            Message message = consumer.receive();
            onMessage(message);
        } catch (JMSException e) {
            e.printStackTrace();
        }
        try {
            Thread.sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

@Override
public void onMessage(Message message) {
    System.out.println("onMessage");
    messagesReceived++;

    if (message instanceof TextMessage) {
        try {
            TextMessage txtMsg = (TextMessage) message;
            String msg = txtMsg.getText();

            if(!client.sendMessage(msg)) {
                System.out.println("Webservice call failed. Keeping message");
                //message.
            } else {
                message.acknowledge();
            }

            if (transacted) {
                if ((messagesReceived % batch) == 0) {
                    System.out.println("Commiting transaction for last " + batch + " messages; messages so far = " + messagesReceived);
                    session.commit();
                }
            }
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }
}

我目前没有使用交易(也许我应该这样做？).

我确定我错过了一些简单的东西,很快就会拍打我的额头,但我似乎无法弄清楚这是怎么回事.谢谢!

---

编辑:由于代表不够,我自己无法回答:

好的,经过一些实验,事实证明交易是实现这一目标的唯一方法.这是新代码:

public boolean init() throws JMSException, FileNotFoundException, IOException {
    ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory(user, password, url);
    RedeliveryPolicy policy = new RedeliveryPolicy();
    policy.setInitialRedeliveryDelay(1000L);
    policy.setMaximumRedeliveries(RedeliveryPolicy.NO_MAXIMUM_REDELIVERIES);

    connectionFactory.setRedeliveryPolicy(policy);
    connectionFactory.setUseRetroactiveConsumer(true);
    Connection connection = connectionFactory.createConnection();

    connection.setExceptionListener(this);
    connection.start();

    session = connection.createSession(transacted, ActiveMQSession.CLIENT_ACKNOWLEDGE);
    destination = session.createQueue(subject);

    consumer = session.createConsumer(destination);
}

@Override
public void onMessage(Message message) {
    System.out.println("onMessage");
    messagesReceived++;

    if (message instanceof TextMessage) {
        try {
            TextMessage txtMsg = (TextMessage) message;
            String msg = txtMsg.getText();

            if(client.sendMessage(msg)) {
                if(transacted) {
                    System.out.println("Call succeeded - committing message");
                    session.commit();
                }
                //message.acknowledge();
            } else {
                if(transacted) {
                    System.out.println("Webservice call failed. Rolling back message");
                    session.rollback();
                }
            }

        } catch (JMSException e) {
            e.printStackTrace();
        }
    }
}

现在,按照"重新传递策略"中的指定,每1000毫秒重新发送一条消息.

希望这有助于其他人!:)

Answer 1

您不必使用事务，CLIENT_ACK/Session.recover() 也可以工作......

当发生以下任一情况时，消息将重新传送到客户端：

• 使用事务处理会话并调用 rollback()。
• 事务会话在调用提交之前关闭。
• 会话正在使用 CLIENT_ACKNOWLEDGE 并调用 Session.recover()。

请参阅http://activemq.apache.org/message-redelivery-and-dlq-handling.html