Spring Boot——整合RabbitMQ

1、什么是RabbitMQ？
RabbitMQ 即一个消息队列，主要是用来实现应用程序的异步和解耦，同时也能起到消息缓冲，消息分发的作用。常用的消息中间件有ActiveMQ和RabbitMQ，这里先说RabbitMQ。关于RabbitMQ的基本知识，可以参考：http://blog.720ui.com/2017/rabbitmq_action_01_helloworld/

消息中间件最主要的作用是解耦，中间件最标准的用法是生产者生产消息传送到队列，消费者从队列中拿取消息并处理，生产者不用关心是谁来消费，消费者不用关心谁在生产消息，从而达到解耦的目的。在分布式的系统中，消息队列也会被用在很多其它的方面，比如：分布式事务的支持，RPC的调用等等。参考：http://www.ityouknow.com/springboot/2016/11/30/spring-boot-rabbitMQ.html
Windows环境下的安装RabbitMQ可以参考如下：https://www.cnblogs.com/junrong624/p/4121656.html

2、Spring Boot整合RabbitMQ
A、引入RabbitMQ依赖：

<!-- 增加 RabbitMQ 依赖 -->
<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-amqp</artifactId>
</dependency>

B、配置信息：

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

C、注册队列

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

@Configuration
public class RabbitMQConfig {
    public static final String QUEUE_NAME = "spring-boot_queue";
    @Bean
    public Queue queue() {
        return new Queue(QUEUE_NAME);
    }
}

D、生产者

package com.guxf.demo.service;

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

import com.guxf.demo.domain.RabbitMQConfig;

@Service
public class Sender {
    @Autowired
    private AmqpTemplate rabbitTemplate;
    
    public void send() {
        System.out.println("我是生產者——我要发送消息啦...");
        rabbitTemplate.convertAndSend(RabbitMQConfig.QUEUE_NAME, "HelloWorld!");
    }
}

E、接收者

package com.guxf.demo.service;

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

@Service
public class Receiver {
    @Autowired
    private AmqpTemplate rabbitTemplate;
    
    @RabbitListener(queues = "spring-boot_queue")
    public void receiveMessage(String message) {
        System.out.println("我是接收者，我接到的消息是——" + message );
    }
}

启动Application即可看到成果，下面来看下 RabbitMQ 路由场景：
只需要改队列， 在RabbitMQConfig 中注册转发器，监听等，代码如下：

package com.guxf.demo.domain;

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.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer;
import org.springframework.amqp.rabbit.listener.adapter.MessageListenerAdapter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.guxf.demo.service.Receiver;

@Configuration
public class RabbitMQConfig {
 
    public static final String QUEUE_NAME = "spring-boot";
    public static final String QUEUE_EXCHANGE_NAME = "spring-boot-exchange";
 
    @Bean
    public Queue queue() {
        // 是否持久化
        boolean durable = true; 
        // 仅创建者可以使用的私有队列，断开后自动删除
        boolean exclusive = false; 
        // 当所有消费客户端连接断开后，是否自动删除队列
        boolean autoDelete = false; 
        return new Queue(QUEUE_NAME, durable, exclusive, autoDelete);
    }
 
    @Bean
    public TopicExchange exchange() {
        // 是否持久化
        boolean durable = true;
        // 当所有消费客户端连接断开后，是否自动删除队列
        boolean autoDelete = false;
        return new TopicExchange(QUEUE_EXCHANGE_NAME, durable, autoDelete);
    }
 
    @Bean
    public Binding binding(Queue queue, TopicExchange exchange) {
        return BindingBuilder.bind(queue).to(exchange).with(QUEUE_NAME);
    }
 
    @Bean
    SimpleMessageListenerContainer container(ConnectionFactory connectionFactory,
            MessageListenerAdapter listenerAdapter) {
        SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        container.setQueueNames(QUEUE_NAME);
        container.setMessageListener(listenerAdapter);
        return container;
    }
 
    @Bean
    MessageListenerAdapter listenerAdapter(Receiver receiver) {
        return new MessageListenerAdapter(receiver, "receiveMessage");
    }
}