Spring Boot 2 - RabbitMQ simple example (producer + consumer)

In this article, we would like to show you how to create a simple project that uses RabbitMQ to transfer messages from one application to another using Spring Boot 2.

Definitions:

• producer - the logic that sends messages
• consumer - the logic that receives messages

Requirements

• RabbitMQ

  • Installation as service: RabbitMQ - service installation under Windows

  • Installation with Docker: Rabbitmq - Official Image | Docker Hub

  Hint:

  Default configuration to get connection with RabbitMQ is:

  host:     localhost
  port:     5672
  username: guest
  password: guest

Spring Boot 2 Applications

Producer application example

Project structure:

DemoApplication.java file:

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}
}

ProducerConfig.java file:

package com.example.demo;

import org.springframework.amqp.core.Queue;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class ProducerConfig {

    @Bean
    public Queue myQueue() {  // creates my-queue automatically on the RabbitMQ server if not available
        return new Queue("my-queue");
    }
}

ProducerController.java file:

package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class ProducerController {

    @Autowired
    private ProducerService producerService;

    @RequestMapping("/test")
    @ResponseBody
    public void test() {
        this.producerService.sendMessage("Testing message...");
    }
}

ProducerService.java file:

package com.example.demo;

import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class ProducerService {

    @Autowired
    private RabbitTemplate template;

    public void sendMessage(String message) {
        this.template.convertAndSend("my-queue", message);  // sends string message to my-queue
    }
}

application.properties file:

server.port=8081

spring.rabbitmq.host=localhost
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest

Consumer application example

Project structure:

DemoApplication.java file:

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}
}

ConsumerConfig.java file:

package com.example.demo;

import org.springframework.amqp.core.Queue;
import org.springframework.amqp.rabbit.annotation.EnableRabbit;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableRabbit
public class ConsumerConfig {

    @Bean
    public Queue myQueue() {  // creates my-queue automatically on the RabbitMQ server if not available
        return new Queue("my-queue");
    }
}

ConsumerService.java file:

package com.example.demo;

import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Service;

@Service
public class ConsumerService {

    @RabbitListener(queues = "my-queue")
    public void handleMyQueue(String message) {  // receives string message from my-queue
        System.out.println("Message: " + message);
    }
}

application.properties file:

server.port=8082

spring.rabbitmq.host=localhost
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest

Common files

pom.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

	<modelVersion>4.0.0</modelVersion>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.7.0</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<groupId>com.example</groupId>
	<artifactId>demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<name>demo</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>11</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>                                           <!-- --- required -->
			<groupId>org.springframework.boot</groupId>        <!-- --- required -->
			<artifactId>spring-boot-starter-amqp</artifactId>  <!-- --- required -->
		</dependency>                                          <!-- --- required -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>                                           <!-- --- required for tests only -->
			<groupId>org.springframework.amqp</groupId>        <!-- --- required for tests only -->
			<artifactId>spring-rabbit-test</artifactId>        <!-- --- required for tests only -->
			<scope>test</scope>                                <!-- --- required for tests only -->
		</dependency>                                          <!-- --- required for tests only -->
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

See also

1. RabbitMQ - manage service installed under Windows via web browser