https://kennay-kermani.medium.com/simple-pub-sub-implementation-with-spring-boot-docker-and-rabbitmq-4ed7461de239 - Simple Pub-Sub implementation with Spring Boot, Docker, and RabbitMQ tutorial

application.properties

spring.rabbitmq.listener.simple.acknowledge-mode=manual

DemoEventConsumer.java

package com.example.consumer.event;

import com.example.publisher.config.RabbitMQConfig;
import com.rabbitmq.client.Channel;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.amqp.support.AmqpHeaders;
import org.springframework.messaging.handler.annotation.Header;
import org.springframework.stereotype.Component;

import java.io.IOException;

@Component
public class DemoEventConsumer {

    @RabbitListener(queues = RabbitMQConfig.QK_EXAMPLE_QUEUE)
    public void onMessageReceived(String message, Channel channel, @Header(AmqpHeaders.DELIVERY_TAG) long tag) throws IOException {
        System.out.println("Message received!: " + message);
        
        try{
            channel.basicAck(tag, false);   
        }catch (Exception e) {
            channel.basicNack(tag, false, true);
        }
    }
}

DemoEventController.java

package com.example.publisher.event;

import com.example.publisher.config.RabbitMQConfig;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;

import java.text.SimpleDateFormat;

@Controller
public class DemoEventController {

    private final RabbitTemplate rabbitTemplate;

    public DemoEventController(RabbitTemplate rabbitTemplate) {
        this.rabbitTemplate = rabbitTemplate;
    }

    @PostMapping("/event")
    ResponseEntity<Void> postEventMessage() {
        final String timeNowMessage = String.format("%s - %s", "ExampleMessage", getTimeNowRepresentation());
        rabbitTemplate.convertAndSend(RabbitMQConfig.QK_EXAMPLE_QUEUE, timeNowMessage);
        return new ResponseEntity<>(HttpStatus.OK);
    }

    private String getTimeNowRepresentation() {
        long now = System.currentTimeMillis();
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("hh:mm:ss");
        return simpleDateFormat.format(now);
    }
}

docker-command

docker run --rm -it --hostname demo-tutorial-rabbit -p 15672:15672 -p 5672:5672 rabbitmq:3-management

RabbitMQConfig.java

package com.example.publisher.config;

import org.springframework.amqp.core.Queue;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.amqp.support.converter.MessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class RabbitMQConfig {

    public static final String QK_EXAMPLE_QUEUE = "exampleQueue";

    @Bean
    public RabbitTemplate jsonRabbitTemplate(ConnectionFactory connectionFactory) {
        RabbitTemplate template = new RabbitTemplate(connectionFactory);
        template.setMessageConverter(jsonConverter());
        return template;
    }

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

    @Bean
    public Queue exampleQueue() {
        return new Queue(QK_EXAMPLE_QUEUE);
    }
}

terminal-test-post

curl -X POST http://localhost:8080/event