RabbitMQ 9：原生Java客户端+死信交换器DLX

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死信交换器结合消息过期机制一般用在“限时订单”业务场景

1.创建生产者DlxProducer

package com.rabbit.fisher.dlx;

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

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

/**
 *生产者
 */
public class DlxProducer
{

    public final static String EXCHANGE_NAME="dlx_logs";
    public final static String DLX_EXCHANGE_NAME="dlx_accept";

    public static void main( String[] args ) throws IOException, TimeoutException {
        //创建链接、连接到MQ
        ConnectionFactory connectionFactory = new ConnectionFactory();
        //设置连接工厂的连接地址(默认端口5672)
        connectionFactory.setHost("192.168.42.111");
        //设置虚拟主机
        connectionFactory.setVirtualHost("fisher");
        //设置用户名
        connectionFactory.setUsername("fisher");
        //设置密码
        connectionFactory.setPassword("123456");
        //创建连接
        Connection connection = connectionFactory.newConnection();
        //创建信道
        Channel channel = connection.createChannel();
        //在信道中设置交换器
        channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.TOPIC);
        //在消费者中申明队列

        //申明路由键及消息体
        String[] routeKeys={"rabbit","rocket","kafka"};
        for (int i = 0; i < 3; i++) {
            String route = routeKeys[i % 3];
            String msg = "Hello World" + (i+1);
            //发布消息(设置交换器、路由键、参数、消息内容)
            channel.basicPublish(EXCHANGE_NAME, route, null, msg.getBytes());
            System.out.println("Send:" + route + ";" + msg);
        }
        //关闭信道
        channel.close();
        //关闭连接
        connection.close();
    }
}

2.创建消费者MakeDlxConsumer，只消费rabbit路由键绑定的消息，其他消息拒绝消费进入死信队列；并设置死信交换器

package com.rabbit.fisher.dlx;

import com.rabbitmq.client.*;

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

/**
 *普通消费者，不消费的消息将进入死信队列
 */
public class MakeDlxConsumer
{

    public static void main( String[] args ) throws IOException, TimeoutException {
        //创建链接、连接到MQ
        ConnectionFactory connectionFactory = new ConnectionFactory();
        //设置连接工厂的连接地址(默认端口5672)
        connectionFactory.setHost("192.168.42.111");
        //设置虚拟主机
        connectionFactory.setVirtualHost("fisher");
        //设置用户名
        connectionFactory.setUsername("fisher");
        //设置密码
        connectionFactory.setPassword("123456");
        //创建连接
        Connection connection = connectionFactory.newConnection();
        //创建信道
        final Channel channel = connection.createChannel();
        //在信道中设置交换器
        channel.exchangeDeclare(DlxProducer.EXCHANGE_NAME, BuiltinExchangeType.TOPIC);
        Map<String, Object> map = new HashMap<>();
        //设置死信交换器
        map.put("x-dead-letter-exchange", DlxProducer.DLX_EXCHANGE_NAME);
        //死信路由键，会替换消息原来的路由键
        map.put("x-dead-letter-routing-key", "deal");

        //申明队列
        String queueName = "make_dlx";
        channel.queueDeclare(queueName, false, false, false, map);

        //绑定#
        channel.queueBind(queueName, DlxProducer.EXCHANGE_NAME, "#");
        System.out.println("waiting for message ......");

        //申明一个消费者
        final 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");
                //如果是rabbit的消息就手动确认
                if (envelope.getRoutingKey().equals("rabbit")) {
                    System.out.println("Receive[" + envelope.getRoutingKey() + "]" + message);
                    //单条确认
                    channel.basicAck(envelope.getDeliveryTag(), false);
                }else {
                    //如果是其他消息就拒绝（requeue=false），成为死信消息
                    System.out.println("Reject[" + envelope.getRoutingKey() + "]" + message);
                    //拒绝，并不重新投递
                    channel.basicReject(envelope.getDeliveryTag(), false);
                }
            }
        };
        channel.basicConsume(queueName, false, consumer);
    }
}

3.创建消费者MakeDlxConsumer，只消费死信队列内的消息

package com.rabbit.fisher.dlx;

import com.rabbitmq.client.*;

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

/**
 *普通消费者，消费死信队列dlx_consumer的消息
 */
public class DlxConsumer
{

    public static void main( String[] args ) throws IOException, TimeoutException {
        //创建链接、连接到MQ
        ConnectionFactory connectionFactory = new ConnectionFactory();
        //设置连接工厂的连接地址(默认端口5672)
        connectionFactory.setHost("192.168.42.111");
        //设置虚拟主机
        connectionFactory.setVirtualHost("fisher");
        //设置用户名
        connectionFactory.setUsername("fisher");
        //设置密码
        connectionFactory.setPassword("123456");
        //创建连接
        Connection connection = connectionFactory.newConnection();
        //创建信道
        Channel channel = connection.createChannel();
        //在信道中设置交换器
        channel.exchangeDeclare(DlxProducer.DLX_EXCHANGE_NAME, BuiltinExchangeType.TOPIC);
        //申明队列
        String queueName = "dlx_consumer";
        channel.queueDeclare(queueName, false, false, false, null);

        //绑定#
        channel.queueBind(queueName, DlxProducer.DLX_EXCHANGE_NAME, "#");
        System.out.println("waiting for message ......");

        //申明一个消费者
        final 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("Receive dead letter[" + envelope.getRoutingKey() + "]" + message);
            }
        };
        //消费者自动确认
        channel.basicConsume(queueName, true, consumer);
    }
}

4.先启动消费者，再启动生产者

5.查看消费者MakeDlxConsumer打印，消费一条rabbit消息，拒绝两条消息

6.查看消费者DlxConsumer打印，消费了两条死信队列内的消息