[FIXED] Argument type error with Spring AMQP receiver

Issue

My Spring AMQP application has been logging the following exception on initiation:

org.springframework.amqp.rabbit.listener.exception.ListenerExecutionFailedException: Failed to invoke target method 'receiveMessage' with argument type = [class [B], value = [{[B@660cff44}]

From my searching I understand that this is because there is a class incompatibility with the message type? However, I am not able to see where this is.

The following are the relevant code segments:

@Bean
public MessageConverter jsonMessageConverter(){
    return new Jackson2JsonMessageConverter();
}

@Bean
Queue queue() {
    return new Queue(config.getAMQPResultsQueue(), false);
}

@Bean
TopicExchange exchange() {
    return new TopicExchange(config.getAMQPResultsExchange());
}

@Bean
Binding binding(Queue queue, TopicExchange exchange) {
    return BindingBuilder.bind(queue).to(exchange).with("#");
}

@Bean
SimpleMessageListenerContainer container(ConnectionFactory connectionFactory, MessageListenerAdapter listenerAdapter) {
    SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
    container.setConnectionFactory(connectionFactory);
    container.setQueueNames(config.getAMQPResultsQueue());
    container.setMessageListener(listenerAdapter);
    container.setMessageConverter(jsonMessageConverter());
    return container;
}

@Bean
MessageListenerAdapter listenerAdapter(Receiver receiver) {
    return new MessageListenerAdapter(receiver, "receiveMessage");
}

and

@Component
public class Receiver {
    public void receiveMessage(String message) {
        System.out.println("Received <" + message + ">");
    }
}

I have tried setting the class of message to Byte[] but the result is the same. I am sure I am missing something simple - just not sure what it is!

Solution

The Jackson2JsonMessageConverter will only perform conversion if the message has a content_type header that contains json.

Otherwise, it will return byte[].

byte[] will also not be converted to Byte[]. Set the header or use byte[].

Answered By - Gary Russell
Answer Checked By - Gilberto Lyons (JavaFixing Admin)