How to use

setMessagesPerAck

method

in

org.springframework.amqp.rabbit.listener.DirectMessageListenerContainer

/**
 * @param messagesPerAck the messages per ack.
 * @return the spec.
 * @see DirectMessageListenerContainer#setMessagesPerAck(int)
 */
public DirectMessageListenerContainerSpec messagesPerAck(int messagesPerAck) {
  this.listenerContainer.setMessagesPerAck(messagesPerAck);
  return this;
}

/**
 * @param messagesPerAck the messages per ack.
 * @return the spec.
 * @see DirectMessageListenerContainer#setMessagesPerAck(int)
 */
public DirectMessageListenerContainerSpec messagesPerAck(int messagesPerAck) {
  this.listenerContainer.setMessagesPerAck(messagesPerAck);
  return this;
}

@Override
protected void initializeContainer(DirectMessageListenerContainer instance, RabbitListenerEndpoint endpoint) {
  super.initializeContainer(instance, endpoint);
  if (this.taskScheduler != null) {
    instance.setTaskScheduler(this.taskScheduler);
  }
  if (this.monitorInterval != null) {
    instance.setMonitorInterval(this.monitorInterval);
  }
  if (endpoint != null && endpoint.getConcurrency() != null) {
    try {
      instance.setConsumersPerQueue(Integer.parseInt(endpoint.getConcurrency()));
    }
    catch (NumberFormatException e) {
      throw new IllegalStateException("Failed to parse concurrency: " + e.getMessage(), e);
    }
  }
  else if (this.consumersPerQueue != null) {
    instance.setConsumersPerQueue(this.consumersPerQueue);
  }
  if (this.messagesPerAck != null) {
    instance.setMessagesPerAck(this.messagesPerAck);
  }
  if (this.ackTimeout != null) {
    instance.setAckTimeout(this.ackTimeout);
  }
}

container.setPrefetchCount(2);
container.setMonitorInterval(100);
container.setMessagesPerAck(10);
container.setAckTimeout(100);
container.setMessageListener(m -> {

@Test
public void testDeferredAcks() throws Exception {
  CachingConnectionFactory cf = new CachingConnectionFactory("localhost");
  DirectMessageListenerContainer container = new DirectMessageListenerContainer(cf);
  final CountDownLatch latch = new CountDownLatch(2);
  container.setMessageListener(m -> {
    latch.countDown();
  });
  container.setQueueNames(Q1);
  container.setBeanName("deferredAcks");
  container.setMessagesPerAck(2);
  container.afterPropertiesSet();
  container.start();
  RabbitTemplate rabbitTemplate = new RabbitTemplate(cf);
  rabbitTemplate.convertAndSend(Q1, "foo");
  rabbitTemplate.convertAndSend(Q1, "bar");
  assertTrue(latch.await(10, TimeUnit.SECONDS));
  container.stop();
  cf.destroy();
}