RabbitMQ 交换机类型

常用交换机

一个生产者给多个队列发送消息，X 代表交换机。

交换机的作用：类似网络路由器，主要提供转发功能，解决怎么把消息转发到不同的队列中，让消费者从不同队列取然后消费。

绑定：交换机和队列关联起来

发布订阅交换机，队列进行持久化，生产者发布消息，所有消费者都能接收到消息。

生产者代码

java 复制代码

public class FanoutProducer{

  private static final String EXCHANGE_NAME = "fanout_exchange";

  public static void main(String[] argv) throws Exception {
    ConnectionFactory factory = new ConnectionFactory();
    factory.setHost("localhost");
    try (Connection connection = factory.newConnection();
         Channel channel = connection.createChannel()) {
        //创建交换机，参数：交换机名称，交换机类型
        channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNext()){
            String message = scanner.nextLine();
            //第二个参数是路由规则
            channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes("UTF-8"));
            System.out.println(" [x] Sent '" + message + "'");
        }

    }
  }
}

消费者代码

java 复制代码

public class FanoutConsumer {
    private static final String EXCHANGE_NAME = "fanout_exchange";

    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        //绑定交换机，以及设置绑定规则
        channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
        String queueName1 = "xiaowang";
        String queueName2 = "xiaoli";
        channel.queueDeclare(queueName1, true, false, false, null);
        channel.queueDeclare(queueName2, true, false, false, null);
        //创建队列，不指定队列，随机分配
        //String queueName = channel.queueDeclare().getQueue();
        channel.queueBind(queueName1, EXCHANGE_NAME, "");
        System.out.println(" [xiaowang] Waiting for messages. To exit press CTRL+C");
		//交换机绑定队列
        channel.queueBind(queueName2, EXCHANGE_NAME, "");
        System.out.println(" [xiaoli] Waiting for messages. To exit press CTRL+C");
        DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(  " [xiaowang] Received '" + message + "'");
        };
        DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(  " [xiaoli] Received '" + message + "'");
        };
        channel.basicConsume(queueName1, true, deliverCallback1, consumerTag -> {
        });
        channel.basicConsume(queueName2, true, deliverCallback2, consumerTag -> {
        });
    }
}

channel 频道：理解为操作消息队列的 Client，通过 channel 收发消息，提供了和消息对了 server 建立通信的传输方法

channel.queueDeclare 方法参数：

queue：这是一个字符串参数，代表要声明的队列的名称。如果队列不存在，则会自动创建一个新的队列。

durable：这是一个布尔值参数，表示队列是否持久化。如果设置为true，则队列会在服务器重启后仍然存在；如果设置为false，则队列在服务器重启后会被删除。默认值为false。

exclusive：这也是一个布尔值参数，表示队列是否为独占模式。如果设置为true，则只有当前连接可以访问该队列；如果设置为false，则其他连接也可以访问该队列。默认值为false。

autoDelete：这是另一个布尔值参数，表示队列是否自动删除。如果设置为true，则当最后一个消费者取消订阅时，队列将被删除；如果设置为false，则队列将一直存在，直到手动删除或服务器重启。默认值为false。

arguments：这是一个可选参数，用于设置队列的其他属性，比如消息的最大长度、最大优先级等。

channel.basicPublish 参数：

exchange：这是一个字符串参数，代表交换机的名称。如果不需要使用特定的交换机，可以传递一个空字符串（""）。交换机是RabbitMQ中用于接收生产者发送的消息并根据绑定规则路由到队列的组件。

routingKey：这也是一个字符串参数，它指定了发布消息的队列。无论通道绑定到哪个队列，最终发布的消息都会包含这个指定的路由键。路由键是用来确定消息应该发送到哪个队列的重要信息。

message：这是要发布的消息本身，通常是字节数组的形式。

properties：这是一个可选参数，用于设置消息的属性，比如消息的优先级、过期时间等。

在使用channel.basicPublish时，需要注意以下几点：

exchange和routingKey不能为空：在AMQImpl类中的实现要求这两个参数都不能为null，否则会抛出异常。

交换机类型：根据不同的需求，可以选择不同类型的交换机，如fanout、direct或topic。每种类型的交换机都有其特定的路由规则。

非命名队列：在某些情况下，比如日志系统，可以使用非命名队列，这样消费者可以接收到所有相关的日志消息，而不是特定的部分。

channel.basicConsume 参数：

queue：这是一个字符串参数，代表要消费的队列的名称。如果队列不存在，则会抛出异常。

onMessage：这是一个回调函数，当有新的消息到达时会被调用。该函数需要接收两个参数：一个表示消息内容的Delivery对象和一个表示通道的Channel对象。

consumerTag：这是一个可选参数，用于标识消费者。如果没有指定，则会自动生成一个唯一的标识符。

autoAck：这是一个布尔值参数，表示是否自动确认消息。如果设置为true，则在消息被处理后会自动发送确认信息；如果设置为false，则需要手动发送确认信息。默认值为false。

arguments：这是一个可选参数，用于设置消费者的其他属性，比如消息的最大长度、最大优先级等。

在使用channel.basicConsume时，需要注意以下几点：

队列名称：队列名称应该是唯一的，否则会抛出异常。

消息处理：在onMessage回调函数中，需要对消息进行处理，并根据需要发送确认信息。

消费者标识符：可以通过设置consumerTag来标识消费者，以便在后续操作中进行识别和管理。

消费者属性：可以通过设置消费者的其他属性来控制消费者的行为，比如设置消息的最大长度、最大优先级等。

路由交换机（Direct exchange)

和订阅发布的区别是在交换机和队列之间有一个路由键，用来控制消息发送到哪个队列中供消费者消费。生产者给交换机一个标识，让交换机给指定的队列转发消息。

生产者代码

java 复制代码

public class DirectProducer {

    private static final String EXCHANGE_NAME = "direct_exchange";

    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        try (Connection connection = factory.newConnection();
             Channel channel = connection.createChannel()) {
            //创建交换机，交换机类型是 direct
            channel.exchangeDeclare(EXCHANGE_NAME, "direct");
            Scanner scanner = new Scanner(System.in);
            while (scanner.hasNext()){
                String userInput = scanner.nextLine();
                //输入的时候带着标识，标识就是路由键
                String[] strs = userInput.split(" ");
                if(strs.length<1){
                    continue;
                }
                //消息
                String message = strs[0];
                //路由键
                String severity = strs[1];
                //发送消息时带着路由键
                channel.basicPublish(EXCHANGE_NAME, severity, null, message.getBytes("UTF-8"));
                System.out.println(" [x] Sent '" + severity + "':'" + message + "'");
            }
        }
    }
}

消费者代码

java 复制代码

public class DirectConsumer {

    private static final String EXCHANGE_NAME = "direct_exchange";

    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        channel.exchangeDeclare(EXCHANGE_NAME, "direct");
        String queueName1 = "xiaohong";
        String queueName2 = "xiaobai";
        channel.queueDeclare(queueName1, true, false, false, null);
        channel.queueDeclare(queueName2, true, false, false, null);
        //交换机使用路由键绑定队列
        channel.queueBind(queueName1, EXCHANGE_NAME, "xiaohong");
        channel.queueBind(queueName2, EXCHANGE_NAME, "xiaobai");
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(" [xiaohong] Received '" +
                    delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
        };
        DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(" [xiaobai] Received '" +
                    delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
        };
        channel.basicConsume(queueName1, true, deliverCallback1, consumerTag -> {
        });
        channel.basicConsume(queueName2, true, deliverCallback2, consumerTag -> {
        });
    }
}

主题交换机（Topic exchange）

在路由交换机的基础上，消息会具有一个模糊的路由键转发给指定的对俄（一系列的路由键、一类的路由键）

（*）标识匹配一个单词，比如 *.orange 表示 a.orange b.orange 都能匹配
（#）表示 0 个或多个单词，比如 a,#, a.a, a.b 都可以

生产者代码

java 复制代码

public class TopicProduce {

  private static final String EXCHANGE_NAME = "topic_exchange1";

  public static void main(String[] argv) throws Exception {
      ConnectionFactory factory = new ConnectionFactory();
      factory.setHost("localhost");
      try (Connection connection = factory.newConnection();
           Channel channel = connection.createChannel()) {
          channel.exchangeDeclare(EXCHANGE_NAME, "topic");

          Scanner scanner = new Scanner(System.in);
          while (scanner.hasNext()) {
              String userInput = scanner.nextLine();
              String[] strs = userInput.split(" ");
              if (strs.length < 1) {
                  continue;
              }
              //消息
              String message = strs[0];
              //路由键
              String severity = strs[1];

              channel.basicPublish(EXCHANGE_NAME, severity, null, message.getBytes("UTF-8"));
              System.out.println(" [x] Sent '" + severity + "':'" + message + "'");
          }
      }
  }
}

消费者代码

java 复制代码

public class TopicConsumer {

    private static final String EXCHANGE_NAME = "topic_exchange1";

    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.exchangeDeclare(EXCHANGE_NAME, "topic");
        channel.exchangeDeclare(EXCHANGE_NAME, "topic");
        channel.exchangeDeclare(EXCHANGE_NAME, "topic");
        String queueName1 = "xiaohei";
        String queueName2 = "xiaolv";
        String queueName3 = "xiaohuang";
        channel.queueDeclare(queueName1, true, false, false, null);
        channel.queueDeclare(queueName2, true, false, false, null);
        channel.queueDeclare(queueName3, true, false, false, null);
        //交换机使用路由键绑定队列，路由键绑定在第三个参数
        channel.queueBind(queueName1, EXCHANGE_NAME, "#.前端.#");
        channel.queueBind(queueName2, EXCHANGE_NAME, "#.后端.#");
        channel.queueBind(queueName2, EXCHANGE_NAME, "#.产品.#");
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
        //收到消息后如何处理
        DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(" [xiaohei] Received '" + delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
        };
        DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(" [xiaolv] Received '" + delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
        };
        DeliverCallback deliverCallback3 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(" [xiaohuang] Received '" + delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
        };
        channel.basicConsume(queueName1, true, deliverCallback1, consumerTag -> {
        });
        channel.basicConsume(queueName2, true, deliverCallback2, consumerTag -> {
        });
        channel.basicConsume(queueName3, true, deliverCallback3, consumerTag -> {
        });


    }
}

核心机制

消息过期机制

官方文档：Preventing Unbounded Buffers with RabbitMQ | RabbitMQ

每个消息指定一个有效期，一段时间内没有被消费者处理，就过期了。

比如消费者挂了，消息一直不被处理，订单就会失效。

可以清理过期的数据，模拟延迟队列的实现。

给每条消息都设置过期时间：

java 复制代码

Map<String, Object> args = new HashMap<String, Object>();
args.put("x-message-ttl", 60000);
channel.queueDeclare(QUEUE_NAME, false, false, false, args);

给队列设置过期时间，设置在生产者中

java 复制代码

AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
        .expiration("1000")
        .build();

生产者代码

java 复制代码

public class TtlProducer {

  private final static String QUEUE_NAME = "Tll_queue";
  public static void main(String[] argv) throws Exception {
    //创建连接
    ConnectionFactory factory = new ConnectionFactory();
    //设置了本地连接，如果修改了用户名和密码，需要设置
    /*factory.setPassword();
    factory.setUsername();*/
    factory.setHost("localhost");
    //建立连接、创建频道
    //频道，类似客户端，用于调用server
    Connection connection = factory.newConnection();
    Channel channel = connection.createChannel();
    String message = "Hello World!";
    //发消息设置过期时间
    AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
            .expiration("1000")
            .build();
    //发送消息
    channel.basicPublish("",QUEUE_NAME,properties,message.getBytes(StandardCharsets.UTF_8));
    System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

  }
}

消费者代码

java 复制代码

public class TtlConsumer {

  private final static String QUEUE_NAME = "Tll_queue";

  public static void main(String[] argv) throws Exception {
    ConnectionFactory factory = new ConnectionFactory();
    factory.setHost("localhost");
    Connection connection = factory.newConnection();
    Channel channel = connection.createChannel();
    //声明队列，同一个消息队列参数必须一致
    Map<String, Object> args = new HashMap<String, Object>();
    args.put("x-message-ttl", 60000);
    channel.queueDeclare(QUEUE_NAME, false, false, false, args);
    //定义了如何处理消息
    DeliverCallback deliverCallback = (consumerTag, delivery) -> {
      String message = new String(delivery.getBody(), "UTF-8");
      System.out.println(" [x] Received '" + message + "'");
    };
    //接收、消费消息 第二个参数 autoAck
    channel.basicConsume(QUEUE_NAME, true, deliverCallback, consumerTag -> { });
    System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

  }
}

死信队列

官方文档：Dead Letter Exchanges | RabbitMQ

为了保证消息的可靠性，比如每条消息都成功消费，需要提供一个容错机制，即：失效的消息怎么办？

死信：过期的消息、拒收的消息、消息队列满了、处理失败的消息的统称。

死信队列：处理死信的队列。

死信交换机：专门给死信队列转发消息的，存在路由绑定关系

实际就是设置一个普通的队列，专门将死信发送到这个队列中处理。

创建死信交换机和死信队列

java 复制代码

//声明死信交换机
String queueName = "laoban_dlx_queue";
channel.queueDeclare(queueName, true, false, false, null);
channel.queueBind(queueName, EXCHANGE_NAME, "laoban");

给失败之后需要容错处理的队列绑定死信交换机

java 复制代码

args2.put("x-dead-letter-exchange", DEAD_EXCHANGE_NAME);

绑定交换机到死信队列

java 复制代码

args2.put("x-dead-letter-routing-key", "waibao");

生产者代码

java 复制代码

public class DLXDirectProducer {

    private static final String EXCHANGE_NAME = "direct2_exchange";
    private static final String DEAD_EXCHANGE_NAME = "dlx_direct2_exchange";

    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        try (Connection connection = factory.newConnection();
             Channel channel = connection.createChannel()) {
            //声明死信交换机
            channel.exchangeDeclare(DEAD_EXCHANGE_NAME, "direct");
            String queueName = "laoban_dlx_queue";
            channel.queueDeclare(queueName, true, false, false, null);
            channel.queueBind(queueName, DEAD_EXCHANGE_NAME, "laoban");

            String queueName2 = "waibao_dlx_queue";
            channel.queueDeclare(queueName2, true, false, false, null);
            channel.queueBind(queueName2, DEAD_EXCHANGE_NAME, "waibao");
            channel.exchangeDeclare(EXCHANGE_NAME, "direct");
            DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
                String message = new String(delivery.getBody(), "UTF-8");
                System.out.println(" [laoban] Received '" +
                        delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
            };
            DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
                String message = new String(delivery.getBody(), "UTF-8");
                System.out.println(" [waibao] Received '" +
                        delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
            };
            channel.basicConsume(queueName, false, deliverCallback1, consumerTag -> {
            });
            channel.basicConsume(queueName2, false, deliverCallback2, consumerTag -> {
            });
            Scanner scanner = new Scanner(System.in);
            while (scanner.hasNext()){
                String userInput = scanner.nextLine();
                String[] strs = userInput.split(" ");
                if(strs.length<1){
                    continue;
                }
                //消息
                String message = strs[0];
                //路由键
                String severity = strs[1];

                channel.basicPublish(EXCHANGE_NAME, severity, null, message.getBytes("UTF-8"));
                System.out.println(" [x] Sent '" + severity + "':'" + message + "'");
            }

        }
    }
}

消费者代码

java 复制代码

public class DLXDirectConsumer {

    private static final String EXCHANGE_NAME = "direct2_exchange";
    private static final String DEAD_EXCHANGE_NAME = "dlx_direct2_exchange";


    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        channel.exchangeDeclare(EXCHANGE_NAME, "direct");
        //死信交换机绑定工作队列，当信息错误就从工作队列发送到死信交换机
        Map<String, Object> args1 = new HashMap<String, Object>();
        //指定绑定哪个交换机
        args1.put("x-dead-letter-exchange", DEAD_EXCHANGE_NAME);
        //死信要发送到哪个队列
        args1.put("x-dead-letter-routing-key", "laoban");
        String queueName1 = "doghuang";
        channel.queueDeclare(queueName1, true, false, false, args1);
        channel.queueBind(queueName1, EXCHANGE_NAME, "doghuang");

        //绑定cat 队列

        String queueName2 = "catbai";
        Map<String, Object> args2 = new HashMap<String, Object>();
        args2.put("x-dead-letter-exchange", DEAD_EXCHANGE_NAME);
        args2.put("x-dead-letter-routing-key", "waibao");
        channel.queueDeclare(queueName2, true, false, false, args2);
        channel.queueBind(queueName2, EXCHANGE_NAME, "catbai");


        //交换机使用路由键绑定队列
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            channel.basicNack(delivery.getEnvelope().getDeliveryTag(),false,false);
            System.out.println(" [doghuang] Received '" +
                    delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
        };
        DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println(" [catbai] Received '" +
                    delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
        };
        channel.basicConsume(queueName1, false, deliverCallback1, consumerTag -> {
        });
        channel.basicConsume(queueName2, false, deliverCallback2, consumerTag -> {
        });

    }
}

项目实战

项目中使用可以选择两种方法

官方的客户端，兼容性好，灵活，需要自己维护管理
使用封装好的客户端，比如 Spring Boot RabbitMQ Starter

优点：简单易用

缺点：不够灵活，被框架限制

小项目使用封装好的足够

依赖引入

引入和自己 Spring Boot 版本相同的依赖，避免出现不能运行的错误

XML 复制代码

<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-amqp -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-amqp</artifactId>
    <version>2.6.13</version>
</dependency>

引入配置

java 复制代码

rabbitmq:
  host: localhost
  port: 5672
  password: guest
  username: guset

创建交换机和消息队列，这个只需要启动一次创建即可

java 复制代码

/**
 * 只启动一次，创建交换机和消息队列
 */
public class MqInitMain {

    private static final String EXCHANGE_NAME = "code_exchange";
    public static void main(String[] args) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        channel.exchangeDeclare(EXCHANGE_NAME, "direct");

        //绑定一个队列
        String queueName = "code_queue";
        channel.queueDeclare(queueName,true,false,false,null);
        channel.queueBind(queueName,EXCHANGE_NAME,"BI_routingKey");
    }
}

生产者

java 复制代码

/**
 * 生产者
 */
@Component
public class MyMessageProducer {


    @Resource
    private RabbitTemplate rabbitTemplate;

    //1.交换机名称2. 交换机路由键3.发送的消息
    public void sendMessage(String exchange, String routingKey,String message){
        rabbitTemplate.convertAndSend(exchange,routingKey,message);
    }

}

消费者

java 复制代码

/**
 * 消费者
 */
@Component
@Slf4j
public class MessageConsumer {

    @RabbitListener(queues = {"code_queue"},ackMode = "MANUAL")
    public void receiveMessage(String message, Channel channel,@Header(AmqpHeaders.DELIVERY_TAG) long delivery){
        log.info("receiveMessage message={}",message);
        try {
            channel.basicAck(delivery,false);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

测试

java 复制代码

@SpringBootTest
class MyMessageProducerTest {

    @Resource
    private MyMessageProducer myMessageProducer;
    @Test
    void sendMessage() {
        myMessageProducer.sendMessage("code_exchange","BI_routingKey","你好吗");
    }
}

RabbitMQ 交换机类型

常用交换机

发布订阅（Publish/Subscribe）交换机

路由交换机 （Direct exchange)

主题交换机 （Topic exchange）

核心机制

消息过期机制

死信队列

项目实战

路由交换机（Direct exchange)

主题交换机（Topic exchange）