Master Object-Based Messaging in Spring Boot 3 with RabbitMQ – Code Samples & Tips

Spring Boot 3 practical case collection now includes over 90 up‑to‑date examples and promises permanent updates for subscribers.

1. Object‑based message sending and receiving

1.1 Custom message converter

<code>@Bean
public MessageConverter messageConverter() {
    return new Jackson2JsonMessageConverter();
}</code>

1.2 Sending a message

<code>@Resource
private RabbitTemplate rabbitTemplate;

Person person = new Person();
rabbitTemplate.convertAndSend("person.exchange", "person.a", person);
</code>

This automatically converts the Person object to JSON.

1.3 Message listener

<code>@RabbitListener(id = "msg-queue", queues = "msg-queue", ackMode = "AUTO")
public void listener(Person person) {
    System.out.printf("%s - Received message: %s%n", Thread.currentThread().getName(), person.toString());
}
</code>

2. Message validation

2.1 Add validation dependency

<code>&lt;dependency&gt;
  &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
  &lt;artifactId&gt;spring-boot-starter-validation&lt;/artifactId&gt;
&lt;/dependency&gt;
</code>

2.2 Define the message object

<code>public class Person {
    @NotEmpty(message = "Name cannot be empty")
    private String name;
}
</code>

2.3 Configure a validated listener

<code>@Component
@Validated
public class MessageListener {
    @RabbitListener(id = "msg-queue", queues = "msg-queue", ackMode = "AUTO")
    public void listener2(@Valid Person person) {
        System.out.printf("%s - Received message: %s%n", Thread.currentThread().getName(), person.toString());
    }
}
</code>

3. Listening for queue idle state

From Spring AMQP 1.6 you can listen for ListenerContainerIdleEvent when no messages are received for a configured period.

<code>@Component
public class RabbitIdleApplicationListener implements ApplicationListener<ListenerContainerIdleEvent> {
    @Override
    public void onApplicationEvent(ListenerContainerIdleEvent event) {
        System.out.printf("%s - No messages processed, idle time: %s%n",
            Arrays.toString(event.getQueueNames()),
            new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date(event.getIdleTime())));
    }
}
</code>

Configure the interval in application.yml :

<code>spring:
  rabbitmq:
    listener:
      simple:
        idle-event-interval: 5s
</code>

4. Custom message listener container

<code>@Bean
SimpleMessageListenerContainer factoryCreatedContainerNoListener(SimpleRabbitListenerContainerFactory rabbitListenerContainerFactory) {
    SimpleMessageListenerContainer container = rabbitListenerContainerFactory.createListenerContainer();
    container.setListenerId("custom-listener");
    container.setMessageListener(message -> {
        System.out.printf("%s - Detected message: %s%n", Thread.currentThread().getName(), new String(message.getBody()));
    });
    container.setAcknowledgeMode(AcknowledgeMode.AUTO);
    container.setQueueNames("test-1");
    return container;
}
</code>

You can define multiple containers as needed.