Rabbitmq中的死信队列

背景

RabbitMQ死信队列俗称，备胎队列；消息中间件因为某种原因拒收该消息后，可以转移到死信队列中存放，死信队列也可以有交换机和路由key等。

原理

死信队列和普通队列区别不是很大

普通与死信队列都有自己独立的交换机和路由key、队列和消费者。

区别：

1.生产者投递消息先投递到我们普通交换机中，普通交换机在将该消息投到

普通队列中缓存起来，普通队列对应有自己独立普通消费者。

2.如果生产者投递消息到普通队列中，普通队列发现该消息一直没有被消费者消费

的情况下，在这时候会将该消息转移到死信（备胎）交换机中，死信（备胎）交换机

对应有自己独立的死信（备胎）队列对应独立死信（备胎）消费者。

普通队列中，普通队列发现该消息一直没有被消费者消费

的情况下，在这时候会将该消息转移到死信（备胎）交换机中，死信（备胎）交换机

对应有自己独立的死信（备胎）队列对应独立死信（备胎）消费者。

产生死信队列的原因

工具类：

java 复制代码

public class RabbitMqUtils {
    //得到一个连接的 channel
    public static Channel getChannel() throws Exception{
        //创建一个连接工厂
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("127.0.0.1");
        factory.setUsername("guest");
        factory.setPassword("guest");
        //创建连接
        Connection connection = factory.newConnection();
        //创建通道
        Channel channel = connection.createChannel();
        return channel;
    }
}

消息投递到MQ中存放消息已经过期消费者没有及时的获取到我们消息，消息如果存放到mq服务器中过期之后，会转移到备胎死信队列存放。

消息 TTL 过期：

生产者代码：

java 复制代码

public class Producer {
    private static final String NORMAL_EXCHANGE = "normal_exchange";
    public static void main(String[] argv) throws Exception {
        try (Channel channel = RabbitMqUtils.getChannel()) {
            channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
            //设置消息的 TTL 时间
            AMQP.BasicProperties properties = new
                    AMQP.BasicProperties().builder().expiration("10000").build();
            //该信息是用作演示队列个数限制
            for (int i = 1; i <11 ; i++) {
                String message="info"+i;
                channel.basicPublish(NORMAL_EXCHANGE, "zhangsan", properties,
                        message.getBytes());
                System.out.println("生产者发送消息:"+message);
            }
        }
    }
}

消费端：

普通消费：

java 复制代码

public class Consumer01 {
    //普通交换机名称
    private static final String NORMAL_EXCHANGE = "normal_exchange";
    //死信交换机名称
    private static final String DEAD_EXCHANGE = "dead_exchange";
    public static void main(String[] argv) throws Exception {
        Channel channel = RabbitMqUtils.getChannel();
        //声明死信和普通交换机 类型为 direct
        channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
        channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
        //声明死信队列
        String deadQueue = "dead-queue";
        channel.queueDeclare(deadQueue, false, false, false, null);
        //死信队列绑定死信交换机与 routingkey
        channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
        //正常队列绑定死信队列信息
        Map<String, Object> params = new HashMap<>();
        //正常队列设置死信交换机 参数 key 是固定值
        params.put("x-dead-letter-exchange", DEAD_EXCHANGE);
        //正常队列设置死信 routing-key 参数 key 是固定值
        params.put("x-dead-letter-routing-key", "lisi");

        String normalQueue = "normal-queue";
        channel.queueDeclare(normalQueue, false, false, false, params);
        channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");
        System.out.println("等待接收消息.....");
        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println("Consumer01 接收到消息"+message);
        };
        channel.basicConsume(normalQueue, true, deliverCallback, consumerTag -> {
        });
    }
}

死信消费：

java 复制代码

public class Consumer02 {
    private static final String DEAD_EXCHANGE = "dead_exchange";
    public static void main(String[] argv) throws Exception {
        Channel channel = RabbitMqUtils.getChannel();
        channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
        String deadQueue = "dead-queue";
        channel.queueDeclare(deadQueue, false, false, false, null);
        channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
        System.out.println("等待接收死信队列消息.....");
        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println("Consumer02 接收死信队列的消息" + message);
        };
        channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {
        });
    }
}

运行结果查询:

1.启动消费端->启动死信队列 ->启动生产者查看结果

2.关闭消费端->启动生产者再次查看结果 结果原因：消费端队列关闭，消息时间过期会进入死信队列

队列达到最大的长度（队列容器已经满了）

生产者代码：

java 复制代码

public class Producer {
    private static final String NORMAL_EXCHANGE = "normal_exchange";
    public static void main(String[] argv) throws Exception {
        try (Channel channel = RabbitMqUtils.getChannel()) {
            channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);

            //该信息是用作演示队列个数限制
            for (int i = 1; i <11 ; i++) {
                String message="info"+i;
                channel.basicPublish(NORMAL_EXCHANGE, "zhangsan", null,
                        message.getBytes());
                System.out.println("生产者发送消息:"+message);
            }
        }
    }
}

消费端：

普通消费：

java 复制代码

public class Consumer01 {
    //普通交换机名称
    private static final String NORMAL_EXCHANGE = "normal_exchange";
    //死信交换机名称
    private static final String DEAD_EXCHANGE = "dead_exchange";
    public static void main(String[] argv) throws Exception {
        Channel channel = RabbitMqUtils.getChannel();
        //声明死信和普通交换机 类型为 direct
        channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
        channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
        //声明死信队列
        String deadQueue = "dead-queue";
        channel.queueDeclare(deadQueue, false, false, false, null);
        //死信队列绑定死信交换机与 routingkey
        channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
        //正常队列绑定死信队列信息
        Map<String, Object> params = new HashMap<>();
        //正常队列设置死信交换机 参数 key 是固定值
        params.put("x-dead-letter-exchange", DEAD_EXCHANGE);
        //正常队列设置死信 routing-key 参数 key 是固定值
        params.put("x-dead-letter-routing-key", "lisi");
        params.put("x-max-length",6); //设置队列长度为6

        String normalQueue = "normal-queue";
        channel.queueDeclare(normalQueue, false, false, false, params);
        channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");
        System.out.println("等待接收消息.....");
        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println("Consumer01 接收到消息"+message);
        };
        channel.basicConsume(normalQueue, true, deliverCallback, consumerTag -> {
        });
    }
}

死信消费：

java 复制代码

public class Consumer02 {
    private static final String DEAD_EXCHANGE = "dead_exchange";
    public static void main(String[] argv) throws Exception {
        Channel channel = RabbitMqUtils.getChannel();
        channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
        String deadQueue = "dead-queue";
        channel.queueDeclare(deadQueue, false, false, false, null);
        channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
        System.out.println("等待接收死信队列消息.....");
        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println("Consumer02 接收死信队列的消息" + message);
        };
        channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {
        });
    }
}

运行结果查询:

1.启动消费端->启动死信队列 ->启动生产者查看结果

结果原因：消费端队列只能存储6条消息,剩下的消息进入死信队列

3. 消费者消费多次消息失败，就会转移存放到死信队列中

注意：与其他不同的是，需要开启手动应答

生产者代码：

java 复制代码

public class Producer {
    private static final String NORMAL_EXCHANGE = "normal_exchange";
    public static void main(String[] argv) throws Exception {
        try (Channel channel = RabbitMqUtils.getChannel()) {
            channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
            //该信息是用作演示队列个数限制
            for (int i = 1; i <11 ; i++) {
                String message="info"+i;
                channel.basicPublish(NORMAL_EXCHANGE, "zhangsan", null,
                        message.getBytes());
                System.out.println("生产者发送消息:"+message);
            }
        }
    }
}

消费端：

普通消费：

java 复制代码

public class Consumer01 {
    //普通交换机名称
    private static final String NORMAL_EXCHANGE = "normal_exchange";
    //死信交换机名称
    private static final String DEAD_EXCHANGE = "dead_exchange";
    public static void main(String[] argv) throws Exception {
        Channel channel = RabbitMqUtils.getChannel();
        //声明死信和普通交换机 类型为 direct
        channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
        channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
        //声明死信队列
        String deadQueue = "dead-queue";
        channel.queueDeclare(deadQueue, false, false, false, null);
        //死信队列绑定死信交换机与 routingkey
        channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
        //正常队列绑定死信队列信息
        Map<String, Object> params = new HashMap<>();
        //正常队列设置死信交换机 参数 key 是固定值
        params.put("x-dead-letter-exchange", DEAD_EXCHANGE);
        //正常队列设置死信 routing-key 参数 key 是固定值
        params.put("x-dead-letter-routing-key", "lisi");

        String normalQueue = "normal-queue";
        channel.queueDeclare(normalQueue, false, false, false, params);
        channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");
        System.out.println("等待接收消息.....");
        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            if(message.equals("info5")){
                System.out.println("Consumer01 接收到消息" + message + "并拒绝签收该消息");
                //requeue 设置为 false 代表拒绝重新入队 该队列如果配置了死信交换机将发送到死信队列中
                channel.basicReject(delivery.getEnvelope().getDeliveryTag(), false);
            }else {
                System.out.println("Consumer01 接收到消息"+message);
                channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
            }
        };
        boolean autoAck = false;
        channel.basicConsume(normalQueue, autoAck, deliverCallback, consumerTag -> {
        });
    }
}

死信消费：

java 复制代码

public class Consumer02 {
    private static final String DEAD_EXCHANGE = "dead_exchange";
    public static void main(String[] argv) throws Exception {
        Channel channel = RabbitMqUtils.getChannel();
        channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);
        String deadQueue = "dead-queue";
        channel.queueDeclare(deadQueue, false, false, false, null);
        channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");
        System.out.println("等待接收死信队列消息.....");
        DeliverCallback deliverCallback = (consumerTag, delivery) -> {
            String message = new String(delivery.getBody(), "UTF-8");
            System.out.println("Consumer02 接收死信队列的消息" + message);
        };
        channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {
        });
    }
}

运行结果查询:

1.启动消费端->启动死信队列 ->启动生产者查看结果

结果原因：消费端队列消息中为info5时,消费端拒绝签收,只能进入死信队列