RabbitMQ API（五） 死信队列

消息进入死信队列的情况

• 消息被拒绝（basic.reject / basic.nack）并且 requeue = false；
• 消息 TTL 过期；
• 队列达到最大长度；

消费者

• 在某个普通队列的声明中指定为其服务的私信队列；
• 在测试的时候，消费端程序运行起来之后就停止，这个可以模拟出消息的普通队列中超时的情况；

package com.bfxy.rabbitmq.api.dlx;

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

import com.bfxy.rabbitmq.Application;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;
import com.rabbitmq.client.QueueingConsumer.Delivery;

public class Consumer {
    
    public static void main(String[] args) throws Exception {

        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost(Application.HOST);
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        Connection connection = connectionFactory.newConnection();

        Channel channel = connection.createChannel();
        
        String exchangeName = "test_dlx_exchange";
        String routingKey = "dlx.#";
        String queueName = "test_dlx_queue";

        channel.exchangeDeclare(exchangeName, "topic", true, false, null);
        
        Map<String, Object> agruments = new HashMap<String, Object>();
        agruments.put("x-dead-letter-exchange", "dlx.exchange");
        channel.queueDeclare(queueName, true, false, false, agruments);

        channel.queueBind(queueName, exchangeName, routingKey);
        
        channel.exchangeDeclare("dlx.exchange", "topic", true, false, null);
        channel.queueDeclare("dlx.queue", true, false, false, null);
        channel.queueBind("dlx.queue", "dlx.exchange", "#");
        
        channel.basicConsume(queueName, true, new MyConsumer(channel));
        
    }

}

package com.bfxy.rabbitmq.api.dlx;

import java.io.IOException;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;

public class MyConsumer extends DefaultConsumer {

    public MyConsumer(Channel channel) {
        super(channel);
    }

    @Override
    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
        System.err.println("-----------consume message----------");
        System.err.println("consumerTag: " + consumerTag);
        System.err.println("envelope: " + envelope);
        System.err.println("properties: " + properties);
        System.err.println("body: " + new String(body));
    }

}

生产者

• 在消息中设置超时时间，超过这个时间，消息还没被消费，消息就会从普通队列转职为其服务的死信队列；

package com.bfxy.rabbitmq.api.dlx;

import com.bfxy.rabbitmq.Application;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

public class Producer {
    
    public static void main(String[] args) throws Exception {
        
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost(Application.HOST);
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        Connection connection = connectionFactory.newConnection();

        Channel channel = connection.createChannel();
        
        String exchange = "test_dlx_exchange";
        String routingKey = "dlx.save";
        
        String msg = "Hello RabbitMQ DLX Message";
        for(int i =0; i < 1; i++){
            AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
                    .deliveryMode(2)
                    .contentEncoding("UTF-8")
                    .expiration("10000")
                    .build();
            channel.basicPublish(exchange, routingKey, true, properties, msg.getBytes());
        }
        
    }

}