Spring Boot + RabbitMQ (2023) Hello World Example
In this tutorial we will be implementing a RabbitMq with Spring boot with the help of a simple example.RabbitMq is a AMQP broker that is used widely. AMQP stands for Advanced Message Queuing Protocol. RabbitMq is use for sending as well as receiving messages.
Different programming languages as well operating systems support RabbitMq.
The basic flow of RabbitMQ can be expressed as follows-
The Exchange method helps in the routing of messages to zero or more queues. In our example there are two microservices Sender and Receiver,
RabbitMq acts as a middleman for the sender and the receiver.The sender will generate a message and then send the message to the messaging queue.The Receiver then connects to the broker and now the message can be seen by the Receiver.
The digrammatic representation of RabbitMq in our example can be shown in the following manner:-
Installation of RabbitMq
For downloading the RabbitMQ, firstly we need to download Erlang and install the binary file successfully.Now we need to download RabbitMQ and then install RabbitMQ on our system.
Open Command Prompt and go to the location where RabbitMQ is installed and start the server by the following command:-
rabbitmq-server start
install all the plugins using the following command:-
rabbitmq-plugins.bat enable rabbitmq_management
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Project Structure
This will be the standard directory layout for maven project structure-
We need to start by creating a Maven pom.xml(Project Object Model) file. The pom.xml file contains the project configuration details.<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> <groupId>com.codeusingjava</groupId> <artifactId>SpringBootRabbitMQ</artifactId> <version>0.0.1-SNAPSHOT</version> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.3.2.RELEASE</version> </parent> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-amqp</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> <finalName>Spring-Boot-Rabbitmq</finalName> </build> </project>
Create the application.properties class for the configuration. All the configurations related to RabbitMQ are also done in this file.spring.application.name=SpringbootRabbitMQ server.port=8889 spring.rabbitmq.host=localhost spring.rabbitmq.port=5672 spring.rabbitmq.username=guest spring.rabbitmq.password=guest rabbitmq.queue=MessageQueue rabbitmq.exchange=exchange rabbitmq.routingkey=routekey
The configuration class is as follows-
The topicExchange is responsible for matching between the routing key and the pattern.
With the help of binding, we can set up relation between queue and an exchange.package com.codeusingjava.configuration; import org.springframework.amqp.core.Binding; import org.springframework.amqp.core.BindingBuilder; import org.springframework.amqp.core.Queue; import org.springframework.amqp.core.TopicExchange; import org.springframework.beans.factory.annotation.Value; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; @Configuration public class RabbitMqConfig { @Value("") private String qName; @Value("") private String exchange; @Value("") private String routingKey; @Bean Queue qu() { return new Queue(qName, Boolean.FALSE); } @Bean TopicExchange topicExchange() { return new TopicExchange(exchange); } @Bean Binding binding(final Queue q, final TopicExchange topicExchange) { return BindingBuilder.bind(q).to(topicExchange).with(routingKey); } }The controller class is as follows- @ResponseStatus annotation is used to organize with a status code which we can apply to the HttpResponse.package com.codeusingjava.sender.controller; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.amqp.core.Binding; import org.springframework.amqp.rabbit.core.RabbitTemplate; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.HttpStatus; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.ResponseStatus; import org.springframework.web.bind.annotation.RestController; @RestController public class Sender { private static final Logger LOGGER = LoggerFactory.getLogger(Sender.class); @Autowired RabbitTemplate rabbitTemplate; @Autowired Binding binding; @GetMapping(value = "/send/{msg}") @ResponseStatus(code = HttpStatus.OK) public String send(@PathVariable("msg") final String message) { LOGGER.info("Sending message to the queue."); rabbitTemplate.convertAndSend(binding.getExchange(), binding.getRoutingKey(), message); LOGGER.info("Message sent successfully to the queue!!!"); return "Great!! your message is sent"; } }The Receiver class will first read the name of the queue from the Queue Object and then logger will be printed which will contain the messages also.package com.codeusingjava.receiver; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.amqp.core.Queue; import org.springframework.amqp.rabbit.annotation.RabbitListener; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component public class Receiver { private static final Logger LOGGER = LoggerFactory.getLogger(Receiver.class); @Autowired Queue qu; @RabbitListener(queues = "#{qu.getName()}") public void getMsg(final String message) { LOGGER.info("Getting messages....."); LOGGER.info("Finally Receiver received the message and the message is..\n" + message); } }The main class for the SpringbootRabbitMQ application is as follows:-package com.codeusingjava; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class SpringbootRabbitmq { public static void main(String[] args) { SpringApplication.run(SpringbootRabbitmq.class, args); } }
Now we see the console logs. This logs are from the Receiver side.
Type the url http://localhost:15672/#/queues
