Spring Boot RabbitMQ Producer Consumer Example

Table of Contents

Introduction

In this tutorial I will show you how to build producer consumer example using Spring Boot and RabbitMQ. This is also called point-to-point messaging model as there are only one producer or sender and only one consumer or receiver.

RabbitMQ is a message broker; it accepts, stores and forwards binary data or messages. A message producer, a message consumer and a queue participate in this message processing event.

A message producer sends the message to the consumer through queue. A message is stored inside a queue. A queue is bound by host’s memory and disk limit. So, it’s a large memory buffer.

Many producers can send messages to a single queue and many consumers can consume messages from a single queue.

It is not necessary that producer, consumer and broker will reside on the same host. Even an application can be both producer and consumer.

point to point jms

In this example tutorial, I am going to use spring amqp library and a producer that sends a single message and a consumer that receives a single message from the queue & prints it out in the console.

Prerequisites

Java 1.8+, Maven 3.8.2, Spring Boot 2.6.2, Spring Boot AMQP 2.6.2, RabbitMQ Server 3.9.4 – 3.9.13

Project Setup

I am going to create maven based project for this example and the following pom.xml file can be used for your project too.

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.roytuts</groupId>
	<artifactId>spring-rabbitmq-producer-consumer</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.compiler.source>16</maven.compiler.source>
		<maven.compiler.target>16</maven.compiler.target>
	</properties>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.6.2</version>
	</parent>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-amqp</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
		</dependency>
	</dependencies>

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

</project>

application.properties

The application.properties file has the queue name declaration and this file is kept in the class path folder src/main/resources.

queue.name=roytuts.queue

Producer

A Producer or Sender class that sends a message to a queue.

package com.roytuts.spring.rabbitmq.producer;

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

@Component
public class Producer {

	@Autowired
	private Queue queue;

	@Autowired
	private RabbitTemplate rabbitTemplate;

	public void sendMsg(final String msg) {
		rabbitTemplate.convertAndSend(queue.getName(), msg);
		System.out.println("Sent: " + msg);
	}

}

The above class has a method sendMsg() that takes a string as an argument and sends it to the broker or queue. To send the message I have used RabbitTemplate and Queue.

Consumer

A Consumer or Receiver class that consumes message from the broker or queue upon arrival.

package com.roytuts.spring.rabbitmq.consumer;

import org.springframework.amqp.rabbit.annotation.RabbitHandler;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;

@Component
@RabbitListener(queues = "${queue.name}")
public class Consumer {

	@RabbitHandler
	public void receiveMsg(final String msg) {
		System.out.println("Received: " + msg);
	}

}

The above class uses annotation @RabbitListener with queue name, so once a message arrives in the queue, the message will be consumed by the consumer.

Configuration

A Config class that configures beans for Queue, Producer (if required) and Consumer (if required).

package com.roytuts.spring.rabbitmq.producer.consumer.config;

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

import com.roytuts.spring.rabbitmq.consumer.Consumer;
import com.roytuts.spring.rabbitmq.producer.Producer;

@Configuration
public class Config {

	@Value("${queue.name}")
	private String queueName;

	@Bean
	public Queue queue() {
		return new Queue(queueName);
	}

	// @Bean
	public Producer producer() {
		return new Producer();
	}

	// @Bean
	public Consumer consumer() {
		return new Consumer();
	}

}

If you are not using @Component annotation on Producer and Consumer classes then you can declare them as beans using @Bean annotation (omit the comment) in the Config class.

Spring Boot RabbitMQ Main Class

A class that has a main method and @SpringBootApplication annotation will deploy the application in embedded Tomcat server.

package com.roytuts.spring.rabbitmq;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import com.roytuts.spring.rabbitmq.producer.Producer;

@SpringBootApplication
public class RabbitMqProducerConsumerApp implements CommandLineRunner {

	@Autowired
	private Producer producer;

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

	@Override
	public void run(String... args) throws Exception {
		producer.sendMsg("This message passes through RabbitMQ broker");
	}

}

The above class uses CLI interface to run the application because I am not using anything for the web application.

Testing Producer Consumer App

Once you run the above main class, you will see that the producer sent a message and consumer received a message:

Sent: This message passes through RabbitMQ broker
Received: This message passes through RabbitMQ broker

The following queue gets created in the RabbitMQ server:

rabbitmq producer consumer

Hope you got an idea how to work with point-to-point messaging model using RabbitMQ broker.

Source Code

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