RabbitMQ 死信队列是什么鬼？

Java技术栈

www.javastack.cn

关注阅读更多优质文章

[

](https://www.oschina.net/action/GoToLink?url=https%3A%2F%2Fmp.weixin.qq.com%2Fs%3F__biz%3DMzI3ODcxMzQzMw%3D%3D%26mid%3D2247486559%26idx%3D2%26sn%3D0eebf45617fb7be5727712e22aac7fb6%26scene%3D21%23wechat_redirect)

作者：海向
来源：www.cnblogs.com/haixiang/p/10905189.html

死信队列

死信队列：没有被及时消费的消息存放的队列。

消息没有被及时消费的原因：

实现死信队列步骤

首先需要设置死信队列的 exchange 和 queue，然后进行绑定:

Exchange: dlx.exchange Queue: dlx.queue RoutingKey: # 代表接收所有路由 key

然后我们进行正常声明交换机、队列、绑定，只不过我们需要在普通队列加上一个参数即可: arguments.put("x-dead-letter-exchange",' dlx.exchange' )

这样消息在过期、requeue失败、队列在达到最大长度时，消息就可以直接路由到死信队列！RabbitMQ 系列面试题和答案我都整理好了，关注公众号Java技术栈在后台回复面试获取。

`import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
public class DlxProducer {
    public static void main(String[] args) throws Exception {
    //设置连接以及创建 channel 湖绿
        String exchangeName = "test_dlx_exchange";
        String routingKey = "item.update";

        String msg = "this is dlx msg";

        //我们设置消息过期时间，10秒后再消费让消息进入死信队列
        AMQP.BasicProperties properties = new AMQP.BasicProperties().builder()
                .deliveryMode(2)
                .expiration("10000")
                .build();

channel.basicPublish(exchangeName, routingKey, true, properties, msg.getBytes());
System.out.println("Send message : " + msg);

        channel.close();
        connection.close();
    }
}
import com.rabbitmq.client.*;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class DlxConsumer {
    public static void main(String[] args) throws Exception {
    //创建连接、创建channel忽略内容可以在上面代码中获取
        String exchangeName = "test_dlx_exchange";
        String queueName = "test_dlx_queue";
        String routingKey = "item.#";

        //必须设置参数到 arguments 中
        Map<String, Object> arguments = new HashMap<String, Object>();
        arguments.put("x-dead-letter-exchange", "dlx.exchange");

        channel.exchangeDeclare(exchangeName, "topic", true, false, null);
        //将 arguments 放入队列的声明中
        channel.queueDeclare(queueName, true, false, false, arguments);

//一般不用代码绑定，在管理界面手动绑定
channel.queueBind(queueName, exchangeName, routingKey);

        //声明死信队列
        channel.exchangeDeclare("dlx.exchange", "topic", true, false, null);
        channel.queueDeclare("dlx.queue", true, false, false, null);
        //路由键为 # 代表可以路由到所有消息
        channel.queueBind("dlx.queue", "dlx.exchange", "#");

        Consumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope,
                                       AMQP.BasicProperties properties, byte[] body)
                    throws IOException {

String message = new String(body, "UTF-8");
System.out.println(" [x] Received '" + message + "'");

}
};

        //6. 设置 Channel 消费者绑定队列
        channel.basicConsume(queueName, true, consumer);
    }
}
`