How send reply from listener - spring

Question

I am working on homework to my studies with Java and RabbitMQ. I am not familiar much with Spring and RabbitMQ, but I can't handle this problem.
I have 2 single application.
First one, which produces the message (bolid application)
I created a producer of the message (bolid), which every 10 seconds send a message to listeners
#SpringBootApplication
public class BolidApplication implements CommandLineRunner {
public static void main(String[] args) {
SpringApplication.run(BolidApplication.class, args);
}
#Autowired
private RabbitTemplate rabbitTemplate;
#Override
public void run(String... args) throws Exception {
Bolid bolid = new Bolid();
int i = 10;
while (true) {
bolid.setData(new Date());
rabbitTemplate.setReplyAddress("bolidReply");
rabbitTemplate.convertAndSend("RaceExchange", "raceRouting", bolid.toString());
rabbitTemplate.convertAndSend("MonitorExchange", "raceRouting", bolid.toString());
Thread.sleep(15000);
i += 10;
}
}
}
So, I create 2 queue (RaceQueue and MonitorQueue), define exchange and bind them.
I have 2 listeners: RaceListener and MonitorListener.
There is the code of my listeners:
And the second application, which is listeners.
public class RabbitConfig {
private static final String RACE_QUEUE = "RaceQueue";
private static final String MONITOR_QUEUE = "MonitorQueue";
#Bean
Queue myQueue() {
return new Queue(RACE_QUEUE, true);
}
#Bean
Queue monitorQueue() {
return new Queue(MONITOR_QUEUE, true);
}
#Bean
Exchange myExchange() {
return ExchangeBuilder.topicExchange("RaceExchange")
.durable(true)
.build();
}
#Bean
Exchange monitorExchange() {
return ExchangeBuilder.topicExchange("MonitorExchange")
.durable(true)
.build();
}
#Bean
Binding binding() {
// return new Binding(MY_QUEUE, Binding.DestinationType.QUEUE, "MyTopicExchange", "topic", null)
return BindingBuilder
.bind(myQueue())
.to(myExchange())
.with("raceRouting")
.noargs();
}
#Bean
Binding monitorBinding() {
return BindingBuilder
.bind(monitorQueue())
.to(monitorExchange())
.with("raceRouting")
.noargs();
}
#Bean
ConnectionFactory connectionFactory() {
CachingConnectionFactory cachingConnectionFactory = new CachingConnectionFactory("localhost");
cachingConnectionFactory.setUsername("guest");
cachingConnectionFactory.setPassword("guest");
return cachingConnectionFactory;
}
#Bean
MessageListenerContainer rabbitRaceListener() {
SimpleMessageListenerContainer simpleMessageListenerContainer = new SimpleMessageListenerContainer();
simpleMessageListenerContainer.setConnectionFactory(connectionFactory());
simpleMessageListenerContainer.setQueues(myQueue());
simpleMessageListenerContainer.setupMessageListener(new RabbitRaceListener());
return simpleMessageListenerContainer;
}
#Bean
MessageListenerContainer rabbitMonitorListener() {
SimpleMessageListenerContainer simpleMessageListenerContainer = new SimpleMessageListenerContainer();
simpleMessageListenerContainer.setConnectionFactory(connectionFactory());
simpleMessageListenerContainer.setQueues(monitorQueue());
simpleMessageListenerContainer.setupMessageListener(new RabbitMonitorListener());
return simpleMessageListenerContainer;
}
}
From MonitorListener I want to use reply pattern to reply message to my first application (bolid application). So Bolid application can receive my message.
My Code for MonitorListener:
public class RabbitMonitorListener implements MessageListener {
#Autowired
private RabbitTemplate rabbitTemplate;
#Override
public void onMessage(Message message) {
String[] splitted = new String(message.getBody()).split("\\|");
int oilTemperature = Integer.parseInt(splitted[1].split(" ")[2]);
int engineTemperature = Integer.parseInt(splitted[2].split(" ")[2]);
int tirePressure = Integer.parseInt(splitted[3].split(" ")[2]);
System.out.println("message2 = [" + new String(message.getBody()) + "]");
if (oilTemperature > 120 || engineTemperature > 120 || tirePressure > 12) {
System.out.println("SEND REPLY TO BOLID!");
}
if (oilTemperature > 150 || engineTemperature > 150 || tirePressure > 17) {
System.out.println("SEND RELY TO BOLID!");
}
}
}
How can I achieve that? So here I can send the message go back to bolid and on the bolid application I can read it?
EDIT:
I did some research, I want to do it like this way:
public class RabbitMonitorListener implements MessageListener {
#Autowired
private RabbitTemplate rabbitTemplate;
#Override
public void onMessage(Message message) {
String[] splitted = new String(message.getBody()).split("\\|");
int oilTemperature = Integer.parseInt(splitted[1].split(" ")[2]);
int engineTemperature = Integer.parseInt(splitted[2].split(" ")[2]);
int tirePressure = Integer.parseInt(splitted[3].split(" ")[2]);
String response = "Hello";
MessageProperties properties = new MessageProperties();
Message responseMessage = new Message(response.getBytes(), properties);
rabbitTemplate.send(message.getMessageProperties().getReplyTo(), responseMessage);
System.out.println("message2 = [" + new String(message.getBody()) + "]");
if (oilTemperature > 120 || engineTemperature > 120 || tirePressure > 12) {
System.out.println("WARN MECHANICS");
}
if (oilTemperature > 150 || engineTemperature > 150 || tirePressure > 17) {
System.out.println("WARN MECHANICS");
}
}
}
but the rabbitTemplate is null here, so I can't #Autowired it here. How can I have access to rabbitTemplate and method send in MessageListener?

Answer 1

new RabbitRaceListener() - that must be a #Bean too, to get auto wiring.
However, you are over-complicating things; the framework can take care of all of this for you.
See Request/Reply Messaging for the client side - and use convertSendAndReceive() or convertSendAndReceiveAsType().
On the server side, see Annotation-driven Listener Endpoints.
#RabbitListener(queues = "request")
public String handle(String in) {
return in.toUpperCase();
}