1.RabbitMQ介绍

1.1现存问题

服务调用：两个服务调用时，我们可以通过传统的HTTP方式，让服务A直接去调用服务B的接口，但是这种方式是同步的方式，虽然可以采用SpringBoot提供的@Async注解实现异步调用，但是这种方式无法确保请求一定回访问到服务B的接口。[那如何保证服务A的请求信息一定能送达到服务B去完成一些业务操作呢？如何实现异步调用

海量请求：在我们在做一些秒杀业务时，可能会在某个时间点突然出现大量的并发请求，这可能已经远远超过服务器的并发瓶颈，这时我们需要做一些削峰的操作，也就是将大量的请求缓冲到一个队列中，然后慢慢的消费掉。[如何提供一个可以存储千万级别请求的队列呢？

在微服务架构下，可能一个业务会出现同时调用多个其他服务的场景，而且这些服务之间一般会用到Feign的方式进行轻量级的通讯，如果存在一个业务，用户创建订单成功后，还需要去给用户添加积分、通知商家、通知物流系统、扣减商品库存，而在执行这个操作时，如果任意一个服务出现了问题，都会导致整体的下单业务失败，并且会导致给用户反馈的时间延长。这时就造成了服务之间存在一个较高的耦合性的问题。[如何可以降低服务之间的耦合性呢？

1.2 处理问题

RabbitMQ就可以解决上述的全部问题

服务之间如何想实现可靠的异步调用，可以通过RabbitMQ的方式实现，服务A只需要保证可以把消息发送到RabbitMQ的队列中，服务B就一定会消费到队列中的消息只不过会存在一定的延时。异步访问

忽然的海量请求可以存储在RabbitMQ的队列中，然后由消费者慢慢消费掉，RabbitMQ的队列本身就可以存储上千万条消息

在调用其他服务时，如果允许延迟效果的出现，可以将消息发送到RabbitMQ中，再由消费者慢慢消费

2. RabbitMQ介绍

RabbitMQ是实现了高级消息队列协议（AMQP）的开源消息代理软件（亦称面向消息的中间件）。RabbitMQ服务器是用[Erlang](https://baike.baidu.com/item/Erlang)语言编写的，而集群和故障转移是构建在[开放电信平台](https://baike.baidu.com/item/开放电信平台)框架上的。所有主要的[编程语言](https://baike.baidu.com/item/编程语言/9845131)均有与代理接口通讯的[客户端](https://baike.baidu.com/item/客户端/101081)库。

首先RabbitMQ基于AMQP协议开发，所以很多基于AMQP协议的功能RabbitMQ都是支持的，比如SpringCloud中的消息总线bus

其次RabbitMQ是基于Erlang编写，这是也是RabbitMQ天生的优势，Erlang被称为面向并发编程的语言，并发能力极强，在众多的MQ中，RabbitMQ的延迟特别低，在微秒级别，所以一般的业务处理RabbitMQ比Kafka和RocketMQ更有优势。

最后RabbitMQ提供自带了图形化界面，操作方便，还自带了多种集群模式，可以保证RabbitMQ的高可用，并且SpringBoot默认就整合RabbitMQ，使用简单方便。

3.RabbitMQ构架

RabbitMQ的架构可以查看官方地址：https://rabbitmq.com/tutorials/amqp-concepts.html

可以看出RabbitMQ中主要分为三个角色：

- Publisher：消息的发布者，将消息发布到RabbitMQ中的Exchange
- RabbitMQ服务：Exchange接收Publisher的消息，并且根据Routes策略将消息转发到Queue中
- Consumer：消息的消费者，监听Queue中的消息并进行消费

官方提供的架构图相对简洁，我们可以自己画一份相对完整一些的架构图：

可以看出Publisher和Consumer都是单独和RabbitMQ服务中某一个Virtual Host建立Connection的客户端

后续通过Connection可以构建Channel通道，用来发布、接收消息

一个Virtual Host中可以有多个Exchange和Queue，Exchange可以同时绑定多个Queue

在基于架构图查看图形化界面，会更加清晰

4.RabbitMQ通讯方式

4.1 RabbitMQ提供的通讯方式

- [Hello World!](https://rabbitmq.com/tutorials/tutorial-one-python.html)：为了入门操作！
- [Work queues](https://rabbitmq.com/tutorials/tutorial-two-python.html)：一个队列被多个消费者消费
- [Publish/Subscribe](https://rabbitmq.com/tutorials/tutorial-three-python.html)：手动创建Exchange（FANOUT）
- [Routing](https://rabbitmq.com/tutorials/tutorial-four-python.html)：手动创建Exchange（DIRECT）
- [Topics](https://rabbitmq.com/tutorials/tutorial-five-python.html)：手动创建Exchange（TOPIC）
- [RPC](https://rabbitmq.com/tutorials/tutorial-six-python.html)：RPC方式
- [Publisher Confirms](https://rabbitmq.com/tutorials/tutorial-seven-java.html)：保证消息可靠性

5.构建Connection工具类

<dependencies>
    <dependency>
        <groupId>com.rabbitmq</groupId>
        <artifactId>amqp-client</artifactId>
        <version>5.9.0</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
</dependencies>

5.1构建工具类：

package com.mashibing.util;

import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

import java.io.IOException;
import java.util.concurrent.TimeoutException;

/**
 * @author zjw
 * @description
 */
public class RabbitMQConnectionUtil {

    public static final String RABBITMQ_HOST = "192.168.11.32";

    public static final int RABBITMQ_PORT = 5672;

    public static final String RABBITMQ_USERNAME = "guest";

    public static final String RABBITMQ_PASSWORD = "guest";

    public static final String RABBITMQ_VIRTUAL_HOST = "/";

    /**
     * 构建RabbitMQ的连接对象
     * @return
     */
    public static Connection getConnection() throws Exception {
        //1. 创建Connection工厂
        ConnectionFactory factory = new ConnectionFactory();

        //2. 设置RabbitMQ的连接信息
        factory.setHost(RABBITMQ_HOST);
        factory.setPort(RABBITMQ_PORT);
        factory.setUsername(RABBITMQ_USERNAME);
        factory.setPassword(RABBITMQ_PASSWORD);
        factory.setVirtualHost(RABBITMQ_VIRTUAL_HOST);

        //3. 返回连接对象
        Connection connection = factory.newConnection();
        return connection;
    }

}

5.2采用通信方式

5.3 构建生产者：

package com.mashibing.helloworld;

import com.mashibing.util.RabbitMQConnectionUtil;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import org.junit.Test;

/**
 * @author zjw
 * @description
 * @date 2022/1/24 22:54
 */
public class Publisher {

    public static final String QUEUE_NAME = "hello";

    @Test
    public void publish() throws Exception {
        //1. 获取连接对象
        Connection connection = RabbitMQConnectionUtil.getConnection();

        //2. 构建Channel
        Channel channel = connection.createChannel();

        //3. 构建队列
        channel.queueDeclare(QUEUE_NAME,false,false,false,null);

        //4. 发布消息
        String message = "Hello World!";
        channel.basicPublish("",QUEUE_NAME,null,message.getBytes());
        System.out.println("消息发送成功！");
    }
}

5.4消费者：

package com.mashibing.helloworld;

import com.mashibing.util.RabbitMQConnectionUtil;
import com.rabbitmq.client.*;
import org.junit.Test;

import java.io.IOException;

/**
 * @author zjw
 * @description
 * @date 2022/1/24 23:02
 */
public class Consumer {

    @Test
    public void consume() throws Exception {
        //1. 获取连接对象
        Connection connection = RabbitMQConnectionUtil.getConnection();

        //2. 构建Channel
        Channel channel = connection.createChannel();

        //3. 构建队列 //要与publisher的队列保持一直，生产了什么消息就要消费相同的消息否则会报错
        channel.queueDeclare(Publisher.QUEUE_NAME,false,false,false,null);

        //4. 监听消息
        DefaultConsumer callback = new DefaultConsumer(channel){
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                System.out.println("消费者获取到消息：" + new String(body,"UTF-8"));
            }
        };
        channel.basicConsume(Publisher.QUEUE_NAME,true,callback);
        System.out.println("开始监听队列");

        System.in.read();
    }
}

6. Work Queues多个consumer消费

- 生产者：生产者和Hello World的形式是一样的，都是将消息推送到默认交换机。
- 消费者：让消费者关闭自动ack，并且设置消息的流控，最终实现消费者可以尽可能去多消费消息

6.1构建两个consumer

package com.mashibing.workqueues;

import com.mashibing.util.RabbitMQConnectionUtil;
import com.rabbitmq.client.*;
import org.junit.Test;

import java.io.IOException;

/**
 * @author zjw
 * @description
 * @date 2022/1/25 19:52
 */
public class Consumer {

    @Test
    public void consume1() throws Exception {
        //1. 获取连接对象
        Connection connection = RabbitMQConnectionUtil.getConnection();

        //2. 构建Channel
        Channel channel = connection.createChannel();

        //3. 构建队列
        channel.queueDeclare(Publisher.QUEUE_NAME,false,false,false,null);

        //3.5 设置消息的流控消费者一次拿几个消息
        channel.basicQos(3);

        //4. 监听消息
        DefaultConsumer callback = new DefaultConsumer(channel){
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("消费者1号-获取到消息：" + new String(body,"UTF-8"));
				//手动设置Ack
                channel.basicAck(envelope.getDeliveryTag(),false);
            }
        };
        channel.basicConsume(Publisher.QUEUE_NAME,false,callback);//false表示手动设置Ack，true表示自动设置
        System.out.println("开始监听队列");

        System.in.read();
    }

    @Test
    public void consume2() throws Exception {
        //1. 获取连接对象
        Connection connection = RabbitMQConnectionUtil.getConnection();

        //2. 构建Channel
        Channel channel = connection.createChannel();

        //3. 构建队列
        channel.queueDeclare(Publisher.QUEUE_NAME,false,false,false,null);

        channel.basicQos(3);

        //4. 监听消息
        DefaultConsumer callback = new DefaultConsumer(channel){
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("消费者2号-获取到消息：" + new String(body,"UTF-8"));
                channel.basicAck(envelope.getDeliveryTag(),false);
            }
        };
、、
        channel.basicConsume(Publisher.QUEUE_NAME,false,callback);
        System.out.println("开始监听队列");

        System.in.read();
    }
}

6.2构建消息发送者

package com.msb.util.mes;

import com.msb.util.RabbitMQConnectionutil;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import org.junit.Test;

import java.nio.charset.StandardCharsets;

public class Publisher {
    /***
     Connection connection = RabbitMQConnectionutil.getConnection();
     Channel channel = connection.createChannel();
     channel.queueDeclare(HELLO,false,false,false,null);
     String message = "HelloWord";
     channel.basicPublish("",HELLO,null,message.getBytes());
     System.out.println("消息发送成功");
     System.in.read();
     */
    public static final String WORK="work";

    @Test
    public void publish() throws Exception{
        Connection connection = RabbitMQConnectionutil.getConnection();
        Channel channel = connection.createChannel();
        channel.queueDeclare(WORK,false,false,false,null);
        for (int i = 0; i < 10; i++) {
            String ms1 = "Hello World"+i;
            channel.basicPublish("",WORK,null,ms1.getBytes(StandardCharsets.UTF_8));
        }

        System.out.println("消息发送成功");
        System.in.read();
    }
}

7. Publish/Subscribe

生产者：自行构建Exchange并绑定指定队列[（FANOUT类型）]

package com.mashibing.pubsub;

import com.mashibing.util.RabbitMQConnectionUtil;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import org.junit.Test;

/**
 * @author zjw
 * @description
 * @date 2022/1/25 20:08
 */
public class Publisher {

    public static final String EXCHANGE_NAME = "pubsub";
    public static final String QUEUE_NAME1 = "pubsub-one";
    public static final String QUEUE_NAME2 = "pubsub-two";
    @Test
    public void publish() throws Exception {
        //1. 获取连接对象
        Connection connection = RabbitMQConnectionUtil.getConnection();

        //2. 构建Channel
        Channel channel = connection.createChannel();

        //3. 构建交换机
        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT);

        //4. 构建队列
        channel.queueDeclare(QUEUE_NAME1,false,false,false,null);
        channel.queueDeclare(QUEUE_NAME2,false,false,false,null);

        //5. 绑定交换机和队列，使用的是FANOUT类型的交换机，绑定方式是直接绑定
        channel.queueBind(QUEUE_NAME1,EXCHANGE_NAME,"");
        channel.queueBind(QUEUE_NAME2,EXCHANGE_NAME,"");

        //6. 发消息到交换机
        channel.basicPublish(EXCHANGE_NAME,"45jk6h645jk",null,"publish/subscribe!".getBytes());
        System.out.println("消息成功发送！");
    }
}

8. Routing

生产者：在绑定Exchange和Queue时，需要指定好routingKey，同时在发送消息时，也指定routingKey，只有routingKey一致时，才会把指定的消息路由到指定的Queue

package com.mashibing.routing;

import com.mashibing.util.RabbitMQConnectionUtil;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import org.junit.Test;

/**
 * @author zjw
 * @description
 * @date 2022/1/25 20:20
 */
public class Publisher {

    public static final String EXCHANGE_NAME = "routing";
    public static final String QUEUE_NAME1 = "routing-one";
    public static final String QUEUE_NAME2 = "routing-two";
    @Test
    public void publish() throws Exception {
        //1. 获取连接对象
        Connection connection = RabbitMQConnectionUtil.getConnection();

        //2. 构建Channel
        Channel channel = connection.createChannel();

        //3. 构建交换机
        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.DIRECT);

        //4. 构建队列
        channel.queueDeclare(QUEUE_NAME1,false,false,false,null);
        channel.queueDeclare(QUEUE_NAME2,false,false,false,null);

        //5. 绑定交换机和队列
        channel.queueBind(QUEUE_NAME1,EXCHANGE_NAME,"ORANGE");
        channel.queueBind(QUEUE_NAME2,EXCHANGE_NAME,"BLACK");
        channel.queueBind(QUEUE_NAME2,EXCHANGE_NAME,"GREEN");

        //6. 发消息到交换机
        channel.basicPublish(EXCHANGE_NAME,"ORANGE",null,"大橙子！".getBytes());
        channel.basicPublish(EXCHANGE_NAME,"BLACK",null,"黑布林大狸子".getBytes());
        channel.basicPublish(EXCHANGE_NAME,"WHITE",null,"小白兔！".getBytes());
        System.out.println("消息成功发送！");


    }

}

生产者：TOPIC类型可以编写带有特殊意义的routingKey的绑定方式

package com.mashibing.topics;

import com.mashibing.util.RabbitMQConnectionUtil;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import org.junit.Test;

/**
 * @author zjw
 * @description
 * @date 2022/1/25 20:28
 */
public class Publisher {

    public static final String EXCHANGE_NAME = "topic";
    public static final String QUEUE_NAME1 = "topic-one";
    public static final String QUEUE_NAME2 = "topic-two";
    @Test
    public void publish() throws Exception {
        //1. 获取连接对象
        Connection connection = RabbitMQConnectionUtil.getConnection();

        //2. 构建Channel
        Channel channel = connection.createChannel();

        //3. 构建交换机
        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.TOPIC);

        //4. 构建队列
        channel.queueDeclare(QUEUE_NAME1,false,false,false,null);
        channel.queueDeclare(QUEUE_NAME2,false,false,false,null);

        //5. 绑定交换机和队列，
        // TOPIC类型的交换机在和队列绑定时，需要以aaa.bbb.ccc..方式编写routingkey
        // 其中有两个特殊字符：*（相当于占位符），#（相当通配符）
        channel.queueBind(QUEUE_NAME1,EXCHANGE_NAME,"*.orange.*");
        channel.queueBind(QUEUE_NAME2,EXCHANGE_NAME,"*.*.rabbit");
        channel.queueBind(QUEUE_NAME2,EXCHANGE_NAME,"lazy.#");

        //6. 发消息到交换机
        channel.basicPublish(EXCHANGE_NAME,"big.orange.rabbit",null,"大橙兔子！".getBytes());
        channel.basicPublish(EXCHANGE_NAME,"small.white.rabbit",null,"小白兔".getBytes());
        channel.basicPublish(EXCHANGE_NAME,"lazy.dog.dog.dog.dog.dog.dog",null,"懒狗狗狗狗狗狗".getBytes());
        System.out.println("消息成功发送！");

    }
}

9.SpringBoot操作RabbitMQ

9.1 SpringBoot声明信息

- 创建项目
- 导入依赖

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

spring:
  rabbitmq:
    host: 192.168.11.32
    port: 5672
    username: guest
    password: guest
    virtual-host: /

9.2声明交换机&队列

package com.mashibing.rabbitmqboot.config;

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

/**
 * @author zjw
 * @description
 * @date 2022/2/8 20:25
 */
@Configuration
public class RabbitMQConfig {

    public static final String EXCHANGE = "boot-exchange";
    public static final String QUEUE = "boot-queue";
    public static final String ROUTING_KEY = "*.black.*";


    @Bean
    public Exchange bootExchange(){
        // channel.DeclareExchange
        return ExchangeBuilder.topicExchange(EXCHANGE).build();
    }

    @Bean
    public Queue bootQueue(){
        return QueueBuilder.durable(QUEUE).build();
    }

    @Bean
    public Binding bootBinding(Exchange bootExchange,Queue bootQueue){
        return BindingBuilder.bind(bootQueue).to(bootExchange).with(ROUTING_KEY).noargs();
    }
}

9.3生产者操作

package com.mashibing.rabbitmqboot;

import com.mashibing.rabbitmqboot.config.RabbitMQConfig;
import org.junit.jupiter.api.Test;
import org.springframework.amqp.AmqpException;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessagePostProcessor;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

/**
 * @author zjw
 * @description
 * @date 2022/2/8 21:05
 */
@SpringBootTest
public class PublisherTest {

    @Autowired
    public RabbitTemplate rabbitTemplate;

    @Test
    public void publish(){
        rabbitTemplate.convertAndSend(RabbitMQConfig.EXCHANGE,"big.black.dog","message");
        System.out.println("消息发送成功");
    }


    @Test
    public void publishWithProps(){
        rabbitTemplate.convertAndSend(RabbitMQConfig.EXCHANGE, "big.black.dog", "messageWithProps", new MessagePostProcessor() {
            @Override
            public Message postProcessMessage(Message message) throws AmqpException {
                message.getMessageProperties().setCorrelationId("123");
                return message;
            }
        });
        System.out.println("消息发送成功");
    }
}

9.4 消费者操作

package com.mashibing.rabbitmqboot;

import com.mashibing.rabbitmqboot.config.RabbitMQConfig;
import com.rabbitmq.client.Channel;
import org.junit.jupiter.api.Test;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

import java.io.IOException;

/**
 * @author zjw
 * @description
 * @date 2022/2/8 21:11
 */
@Component
public class ConsumeListener {

    @RabbitListener(queues = RabbitMQConfig.QUEUE)
    public void consume(String msg, Channel channel, Message message) throws IOException {
        System.out.println("队列的消息为：" + msg);
        String correlationId = message.getMessageProperties().getCorrelationId();
        System.out.println("唯一标识为：" + correlationId);
        channel.basicAck(message.getMessageProperties().getDeliveryTag(),false);
    }
}

10. RabbitMQ保证消息可靠性（原生api）

产生消息丢失的地方：

1.生产者发消息的时候网络不稳定

2.Exchange不会持久化消息，断电后就会丢失

3.Queue默认是不会持久化消息（只保证队列还在）

4.消费者没有消费Ack模式需要开启

10.1 保证消息一定送达到Exchange

Confirm机制

可以通过Confirm效果保证消息一定送达到Exchange，官方提供了三种方式，选择了对于效率影响最低的异步回调的效果

//4. 开启confirms
channel.confirmSelect();

//5. 设置confirms的异步回调
channel.addConfirmListener(new ConfirmListener() {
    @Override
    public void handleAck(long deliveryTag, boolean multiple) throws IOException {
        System.out.println("消息成功的发送到Exchange！");
    }

    @Override
    public void handleNack(long deliveryTag, boolean multiple) throws IOException {
        System.out.println("消息没有发送到Exchange，尝试重试，或者保存到数据库做其他补偿操作！");
    }
});

10.2保证消息可以路由到Queue

Return机制

为了保证Exchange上的消息一定可以送达到Queue

//6. 设置Return回调，确认消息是否路由到了Queue
channel.addReturnListener(new ReturnListener() {
    @Override
    public void handleReturn(int replyCode, String replyText, String exchange, String routingKey, AMQP.BasicProperties properties, byte[] body) throws IOException {
        System.out.println("消息没有路由到指定队列，做其他的补偿措施！！");
    }
});
//7. 在发送消息时，将basicPublish方法参数中的mandatory设置为true，即可开启Return机制，当消息没有路由到队列中时，就会执行return回调

true只能保证重启后的队列还在但是消息不会存在；解决方法如下：

10.3保证Queue可以持久化消息

DeliveryMode设置消息持久化

DeliveryMode设置为2代表持久化，如果设置为1，就代表不会持久化。

//7. 设置消息持久化
AMQP.BasicProperties props = new AMQP.BasicProperties()
    .builder()
    .deliveryMode(2)
    .build();

//7. 发布消息
channel.basicPublish("","confirms",true,props,message.getBytes());

10.4 保证消费者可以正常消费消息

`详情看WorkQueue模式`

11.pringBoot（ RabbitMQ保证消息可靠性）

11.1 Confirm

- 编写配置文件开启Confirm机制

spring:
  rabbitmq:
    publisher-confirm-type: correlated  # 新版本
    publisher-confirms: true  # 老版本

在发送消息时，配置RabbitTemplate

@Test
public void publishWithConfirms() throws IOException {
    rabbitTemplate.setConfirmCallback(new RabbitTemplate.ConfirmCallback() {
        @Override
        public void confirm(CorrelationData correlationData, boolean ack, String cause) {
            if(ack){
                System.out.println("消息已经送达到交换机！！");
            }else{
                System.out.println("消息没有送达到Exchange，需要做一些补偿操作！！retry！！！");
            }
        }
    });
    rabbitTemplate.convertAndSend(RabbitMQConfig.EXCHANGE,"big.black.dog","message");
    System.out.println("消息发送成功");

    System.in.read();
}

11.2Return

- 编写配置文件开启Return机制

spring:
  rabbitmq:
    publisher-returns: true # 开启Return机制

在发送消息时，配置RabbitTemplate

@Test
public void publishWithReturn() throws IOException {
    // 新版本用 setReturnsCallback ，老版本用setReturnCallback
    rabbitTemplate.setReturnsCallback(new RabbitTemplate.ReturnsCallback() {
        @Override
        public void returnedMessage(ReturnedMessage returned) {
            String msg = new String(returned.getMessage().getBody());
            System.out.println("消息：" + msg + "路由队列失败！！做补救操作！！");
        }
    });
    rabbitTemplate.convertAndSend(RabbitMQConfig.EXCHANGE,"big.black.dog","message");
    System.out.println("消息发送成功");

    System.in.read();
}

11.3消息持久化

@Test
public void publishWithBasicProperties() throws IOException {
    rabbitTemplate.convertAndSend(RabbitMQConfig.EXCHANGE, "big.black.dog", "message", new MessagePostProcessor() {
        @Override
        public Message postProcessMessage(Message message) throws AmqpException {
            // 设置消息的持久化！
            message.getMessageProperties().setDeliveryMode(MessageDeliveryMode.PERSISTENT);
            return message;
        }
    });
    System.out.println("消息发送成功");
}

12.RabbitMQ死信队列&延迟交换机

12.1什么是死信

死信队列的应用：

- 基于死信队列在队列消息已满的情况下，消息也不会丢失
- 实现延迟消费的效果。比如：下订单时，有15分钟的付款时间

12.2实现死信队列

12.3 准备Exchange&Queue

package com.mashibing.rabbitmqboot.config;

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

/**
 * @author zjw
 * @description
 * @date 2022/2/10 15:04
 */
@Configuration
public class DeadLetterConfig {

    public static final String NORMAL_EXCHANGE = "normal-exchange";
    public static final String NORMAL_QUEUE = "normal-queue";
    public static final String NORMAL_ROUTING_KEY = "normal.#";

    public static final String DEAD_EXCHANGE = "dead-exchange";
    public static final String DEAD_QUEUE = "dead-queue";
    public static final String DEAD_ROUTING_KEY = "dead.#";


    @Bean
    public Exchange normalExchange(){
        return ExchangeBuilder.topicExchange(NORMAL_EXCHANGE).build();
    }

    @Bean
    public Queue normalQueue(){
        return QueueBuilder.durable(NORMAL_QUEUE).deadLetterExchange(DEAD_EXCHANGE).deadLetterRoutingKey("dead.abc").build();
    }

    @Bean
    public Binding normalBinding(Queue normalQueue,Exchange normalExchange){
        return BindingBuilder.bind(normalQueue).to(normalExchange).with(NORMAL_ROUTING_KEY).noargs();
    }


    @Bean
    public Exchange deadExchange(){
        return ExchangeBuilder.topicExchange(DEAD_EXCHANGE).build();
    }

    @Bean
    public Queue deadQueue(){
        return QueueBuilder.durable(DEAD_QUEUE).build();
    }

    @Bean
    public Binding deadBinding(Queue deadQueue,Exchange deadExchange){
        return BindingBuilder.bind(deadQueue).to(deadExchange).with(DEAD_ROUTING_KEY).noargs();
    }

}

12.4实现效果

- 基于消费者进行reject或者nack实现死信效果

package com.mashibing.rabbitmqboot;

import com.mashibing.rabbitmqboot.config.DeadLetterConfig;
import com.rabbitmq.client.Channel;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;

import java.io.IOException;

/**
 * @author zjw
 * @description
 * @date 2022/2/10 15:17
 */
@Component
public class DeadListener {

    @RabbitListener(queues = DeadLetterConfig.NORMAL_QUEUE)
    public void consume(String msg, Channel channel, Message message) throws IOException {
        System.out.println("接收到normal队列的消息：" + msg);
        channel.basicReject(message.getMessageProperties().getDeliveryTag(),false);
        channel.basicNack(message.getMessageProperties().getDeliveryTag(),false,false);
    }
}

@Test
public void publishExpire(){
    String msg = "dead letter expire";
    rabbitTemplate.convertAndSend(DeadLetterConfig.NORMAL_EXCHANGE, "normal.abc", msg, new MessagePostProcessor() {
        @Override
        public Message postProcessMessage(Message message) throws AmqpException {
            message.getMessageProperties().setExpiration("5000");
            return message;
        }
    });
}

给队列设置消息的生存时间

@Bean
public Queue normalQueue(){
    return QueueBuilder.durable(NORMAL_QUEUE)
            .deadLetterExchange(DEAD_EXCHANGE)
            .deadLetterRoutingKey("dead.abc")
            .ttl(10000)
            .build();
}

设置Queue中的消息最大长度

@Bean
public Queue normalQueue(){
    return QueueBuilder.durable(NORMAL_QUEUE)
            .deadLetterExchange(DEAD_EXCHANGE)
            .deadLetterRoutingKey("dead.abc")
            .maxLength(1)
            .build();
}

只要Queue中已经有一个消息，如果再次发送一个消息，这个消息会变为死信！

13.延迟交换机

13.1设置死信的问题：

设置死信的生存时间时mq只会按顺序执行，mq只会监听最外侧的消息

如A消息设置了10s的生存时间，B消息设置了5s的生存时间，A先到达队列里面，那么MQ会先开始监听A，A的时间过去了，才会监听B，这时B的生存时间已经过去了，这就会导致B的消息也存活了10s

下载地址：https://github.com/rabbitmq/rabbitmq-delayed-message-exchange/releases/tag/3.8.9

死信队列实现延迟消费时，如果延迟时间比较复杂，比较多，直接使用死信队列时，需要创建大量的队列还对应不同的时间，可以采用延迟交换机来解决这个问题。

安装延时交换机

1.docker cp rabbitmq_delayed_message_exchange-3.8.9-0199d11c.ez rabbitmq_docker_rabbitmq_1:/opt/rabbitmq/plugins

2.rabbitmq-plugins enable rabbitmq_delayed_message_exchang

3.docker restart rabbitmq_docker_rabbitmq_1

13.2构建配置

package com.mashibing.rabbitmqboot.config;

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

import java.util.HashMap;
import java.util.Map;

/**
 * @author zjw
 * @description
 */
@Configuration
public class DelayedConfig {

    public static final String DELAYED_EXCHANGE = "delayed-exchange";
    public static final String DELAYED_QUEUE = "delayed-queue";
    public static final String DELAYED_ROUTING_KEY = "delayed.#";

    @Bean
    public Exchange delayedExchange(){
        Map<String, Object> arguments = new HashMap<>();
        arguments.put("x-delayed-type","topic");
        Exchange exchange = new CustomExchange(DELAYED_EXCHANGE,"x-delayed-message",true,false,arguments);
        return exchange;
    }

    @Bean
    public Queue delayedQueue(){
        return QueueBuilder.durable(DELAYED_QUEUE).build();
    }

    @Bean
    public Binding delayedBinding(Queue delayedQueue,Exchange delayedExchange){
        return BindingBuilder.bind(delayedQueue).to(delayedExchange).with(DELAYED_ROUTING_KEY).noargs();
    }
}

13.3构建消息发送者

import com.mashibing.rabbitmqboot.config.DelayedConfig;
import org.junit.jupiter.api.Test;
import org.springframework.amqp.AmqpException;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessagePostProcessor;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

/**
 * @author zjw
 * @description
 */
@SpringBootTest
public class DelayedPublisherTest {

    @Autowired
    private RabbitTemplate rabbitTemplate;

    @Test
    public void publish(){
        rabbitTemplate.convertAndSend(DelayedConfig.DELAYED_EXCHANGE, "delayed.abc", "xxxx", new MessagePostProcessor() {
            @Override
            public Message postProcessMessage(Message message) throws AmqpException {
                message.getMessageProperties().setDelay(30000);
                return message;
            }
        });
    }
}

14.RabbitMQ的集群

RabbitMQ的镜像模式

14.1搭建RabbitMQ集群

- 准备两台虚拟机（克隆）
- 准备RabbitMQ的yml文件

rabbitmq1：

version: '3.1'
services:
  rabbitmq1:
    image: rabbitmq:3.8.5-management-alpine
    container_name: rabbitmq1
    hostname: rabbitmq1
    extra_hosts:
      - "rabbitmq1:192.168.11.32"
      - "rabbitmq2:192.168.11.33"
    environment: 
      - RABBITMQ_ERLANG_COOKIE=SDJHFGDFFS
    ports:
      - 5672:5672
      - 15672:15672
      - 4369:4369
      - 25672:25672

rabbitmq2：

version: '3.1'
services:
  rabbitmq2:
    image: rabbitmq:3.8.5-management-alpine
    container_name: rabbitmq2
    hostname: rabbitmq2
    extra_hosts:
      - "rabbitmq1:192.168.11.32"
      - "rabbitmq2:192.168.11.33"
    environment: 
      - RABBITMQ_ERLANG_COOKIE=SDJHFGDFFS
    ports:
      - 5672:5672
      - 15672:15672
      - 4369:4369
      - 25672:25672

准备完毕之后，启动两台RabbitMQ

让RabbitMQ服务实现join操作

需要四个命令完成join操作

让rabbitmq2 join rabbitmq1，需要进入到rabbitmq2的容器内部，去执行下述命令

rabbitmqctl stop_app
rabbitmqctl reset
rabbitmqctl join_cluster rabbit@rabbitmq1
rabbitmqctl start_app

执行成功后：

设置镜像模式

在指定的RabbitMQ服务中设置好镜像策略即可

15.Headers类型Exchange

headers就是一个基于key-value的方式，让Exchange和Queue绑定的到一起的一种规则

相比Topic形式，可以采用的类型更丰富。

15.1headers绑定方式

注：x-match为all时代表全匹配只有name与age相同时才能到Queue1中

x-match为any时代表满足一个条件就可以进入到Queue2中

15.2构建config

package com.mashibing.headers;

import com.mashibing.util.RabbitMQConnectionUtil;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import org.junit.Test;

import java.util.HashMap;
import java.util.Map;

/**
 * @author zjw
 * @description
 */
public class Publisher {

    public static final String HEADER_EXCHANGE = "header_exchange";
    public static final String HEADER_QUEUE = "header_queue";


    @Test
    public void publish()throws  Exception{
        //1. 获取连接对象
        Connection connection = RabbitMQConnectionUtil.getConnection();

        //2. 构建Channel
        Channel channel = connection.createChannel();


        //3. 构建交换机和队列并基于header的方式绑定
        channel.exchangeDeclare(HEADER_EXCHANGE, BuiltinExchangeType.HEADERS);
        channel.queueDeclare(HEADER_QUEUE,true,false,false,null);
        Map<String,Object> args = new HashMap<>();
        // 多个header的key-value只要可以匹配上一个就可以
        // args.put("x-match","any");
        // 多个header的key-value要求全部匹配上！
        args.put("x-match","all");
        args.put("name","jack");
        args.put("age","23");
        channel.queueBind(HEADER_QUEUE,HEADER_EXCHANGE,"",args);

        //4. 发送消息
        String msg = "header测试消息！";
        Map<String, Object> headers = new HashMap<>();
        headers.put("name","jac");
        headers.put("age","2");
        AMQP.BasicProperties props = new AMQP.BasicProperties()
                .builder()
                .headers(headers)
                .build();

        channel.basicPublish(HEADER_EXCHANGE,"",props,msg.getBytes());

        System.out.println("发送消息成功，header = " + headers);

    }
}