Spring AMQP - MessageListenerAdapter - pass additional arguments - rabbitmq

Question

To create a SimpleMessageListenerContainer, I do something like this.
SimpleMessageConsumer simpleMessageConsumer = new SimpleMessageConsumer();
MessageListenerAdapter adapter =
new CustomMessageListenerAdapater(simpleMessageConsumer);
adapter.setDefaultListenerMethod("consume");
adapter.setMessageConverter(new SimpleMessageConverter());
SimpleMessageListenerContainer
container =
new SimpleMessageListenerContainer(connectionFactory);
container.setMessageListener(adapter);
My SimpleMessageConsumer
public void consume(String message){
log.info(message);
}
I noticed in the spring-amqp-refrence that the "annotated
listener endpoint infrastructure" allows you to conveniently pass additional Message properties into your consumer like so :
#RabbitListener(queues = "myQueue")
public void processOrder(Order order, #Header("order_type") String orderType) {
...
}
Can that be done using consumer creation approach I mention above? I want to access to some of the headers of the Message object. I know that I can make my consumer implement the MessageListener or the ChannelAwareMessageListener and have access to the entire Message object. However, I dont want the whole Message object, since I like the convenience of using the ContentTypeDelegatingMessageConverter with the Jackson2JsonMessageConverter to do conversion to my desired type(in my real app), before my consumer delegated method is triggered.

Answer 1

public class CustomMessageListenerAdapter extends MessageListenerAdapter {
public CustomMessageListenerAdapter(Object delegate) {
super(delegate);
}
#Override
protected Object invokeListenerMethod(String methodName, Object[] arguments,
Message originalMessage) throws Exception {
Object[] modifiedArguments = new Object[arguments.length+1];
System.arraycopy(arguments, 0, modifiedArguments,
0, arguments.length);
//add the original message with headers
modifiedArguments[arguments.length] = originalMessage;
return super.invokeListenerMethod(methodName, modifiedArguments, originalMessage);
}
}
and my Message consumer now has an additional argument - the original message
public class SimpleMessageConsumer {
private static final Logger log = LoggerFactory.getLogger(SimpleMessageConsumer.class);
public void consume(String messageConverted, Message originalMessage){
log.info(originalMessage.toString());
}
}
My Bean Configuration looks something like this:
SimpleMessageConsumer simpleMessageConsumer = new SimpleMessageConsumer();
MessageListenerAdapter adapter =
new CustomMessageListenerAdapter(simpleMessageConsumer);
adapter.setDefaultListenerMethod("consume");
adapter.setMessageConverter(messageConverter());
//container
SimpleMessageListenerContainer
container =
new SimpleMessageListenerContainer(connectionFactory);
container.setMessageListener(adapter);

Answer 2

You need to use a MessagingMessageConverter with the payloadConverter as the mentioned Jackson2JsonMessageConverter and then in your CustomMessageListenerAdapater you override there a:
/**
* Build an array of arguments to be passed into the target listener method. Allows for multiple method arguments to
* be built from a single message object.
* <p>
* The default implementation builds an array with the given message object as sole element. This means that the
* extracted message will always be passed into a <i>single</i> method argument, even if it is an array, with the
* target method having a corresponding single argument of the array's type declared.
* <p>
* This can be overridden to treat special message content such as arrays differently, for example passing in each
* element of the message array as distinct method argument.
* #param extractedMessage the content of the message
* #return the array of arguments to be passed into the listener method (each element of the array corresponding to
* a distinct method argument)
*/
protected Object[] buildListenerArguments(Object extractedMessage) {
casting that extractedMessage to the Message<?> and extract desired headers if that.