SpringBoot 系列 | 第十篇：使用RabbitMQ收发消息

SpringBoot 系列 | 第十篇：使用RabbitMQ收发消息

本篇文章参考了官方文档:Messaging with RabbitMQ

Spring Boot中使用RabbitQM需要机器安装好RabbitMQ。没有了解RabbitMQ的可以参考一下文章：

• RabbitMq使用 | 第一篇：安装和Hello World
• RabbitMq使用 | 第二篇：消息队列和确认
• RabbitMQ使用 | 第三篇：发布/订阅模式
• RabbitMQ 使用 | 第四篇：路由选择

添加依赖

<dependency>
    <groupId>org.springframework.bootgroupId>
    <artifactId>spring-boot-starter-amqpartifactId>
dependency>

配置

spring.rabbitmq.host=120.55.72.39
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest

创建一个消息接受者

@Component
public class Receiver {

    private CountDownLatch latch = new CountDownLatch(1);

    public void receiveMessage(String message) {
        System.out.println("Received <" + message + ">");
        latch.countDown();
    }

    public CountDownLatch getLatch() {
        return latch;
    }
}

这个Receiver是一个简单的POJO，定义了一个方法用于接收消息，名字可以自定义

为了简便，这个POJO有一个CountDownLatch.在这里的场景用于确保消息收到之后程序才会关闭。

注册消息接受者和发送消息

Spring AMQP的RabbitTemplate提供了需要使用RabbitMQ发送和接收消息的功能，需要定义以下配置：

• A message listener container
• Declare the queue,the exchange,and the binding between them
• A components to send some messages to test the listener

SpringBoot自动创建了一个ConnectFactory和一个RabbitTemplate。

程序代码：

@SpringBootApplication
public class Application {

    final static String queueName = "spring-boot";

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

    @Bean
    TopicExchange exchange() {
        return new TopicExchange("spring-boot-exchange");
    }

    @Bean
    Binding binding(Queue queue, TopicExchange exchange) {
        return BindingBuilder.bind(queue).to(exchange).with(queueName);
    }

    @Bean
    SimpleMessageListenerContainer container(ConnectionFactory connectionFactory,
            MessageListenerAdapter listenerAdapter) {
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        container.setQueueNames(queueName);
        container.setMessageListener(listenerAdapter);
        return container;
    }

    @Bean
    MessageListenerAdapter listenerAdapter(Receiver receiver) {
        return new MessageListenerAdapter(receiver, "receiveMessage");
    }

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

上述代码定义了一个listenerAdapter方法声明消息接收监听器，会监听spring-boot队列的消息，因为Receiver是一个POJO,他需要使用一个MessageListenerAdapter来包装，定义了它的接收方法为receiveMessage

发送一条消息

@Component
public class Runner implements CommandLineRunner {

    private final RabbitTemplate rabbitTemplate;
    private final Receiver receiver;
    private final ConfigurableApplicationContext context;

    public Runner(Receiver receiver, RabbitTemplate rabbitTemplate,
            ConfigurableApplicationContext context) {
        this.receiver = receiver;
        this.rabbitTemplate = rabbitTemplate;
        this.context = context;
    }

    @Override
    public void run(String... args) throws Exception {
        System.out.println("Sending message...");
        rabbitTemplate.convertAndSend("spring-boot-exchange","spring-boot", "Hello from RabbitMQ!");
        receiver.getLatch().await(10000, TimeUnit.MILLISECONDS);
        context.close();
    }
}

运行程序，你会发现如下输出：

Sending message...
Received from RabbitMQ!>