rabbimq队列之死信队列和延迟队列_dead letter queue java

        在项目开发设计过程中，我们经常用到异步推送的场景，比如下单和扣减库存异步执行。常用的异步中间件有mq有很多，我们这里以Rabbitmq为例进行讲解。我们知道只要是涉及异步场景的问题，就有成功失败之分，如果生产者发送消息一直失败要怎么做呢，这里我们就用到了死信队列来实现失败消息的处理。

流程图如下图：

废话不多说直接上代码：

rabbitmq配置类：

package com.mq.test.config;


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

import java.io.IOException;

/**
 * Created by Administrator on 2018/6/7.
 */
public class RabbitmqConfig {
    private final static String IP = "172.16.11.119";
    private final static int PORT = 5672;
    private final static String USERNAME = "root";
    private final static String PASSWORD = "root";
    private static Connection connection = null;
    private static ConnectionFactory factory = null;

    static {
        factory = new ConnectionFactory();
        Address[] addresses = new Address[]{new Address(IP, PORT)};
        factory.setUsername(USERNAME);
        factory.setPassword(PASSWORD);
        try {
            connection = factory.newConnection(addresses);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static Channel getChannel() throws IOException {
        if (connection == null) {
            if (factory != null) {
                return factory.newConnection().createChannel();
            }else{
                return null;
            }
        }
        return connection.createChannel();
    }
}

生产者类：

package com.mq.test;

import com.mq.test.config.RabbitmqConfig;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.MessageProperties;

import java.io.IOException;

/**
 * Created by Administrator on 2018/6/7.
 */
public class MqProducerTest {
    private final static String DLX_EXCHANGE_NAME = "dlx_exchange";
    private final static String NORMAL_EXCHANGE_NAME = "normal_exchange";
//    private final static String DLX_ROUTINGKEY= "dlx";
    private final static String NORMAL_ROUTINGKEY= "normal";
    public static void main(String[] args) throws IOException {
        Channel channel = RabbitmqConfig.getChannel();
        channel.exchangeDeclare(NORMAL_EXCHANGE_NAME,"direct",true);
        channel.exchangeDeclare(DLX_EXCHANGE_NAME,"direct",true);
        channel.basicPublish(NORMAL_EXCHANGE_NAME,NORMAL_ROUTINGKEY, MessageProperties.PERSISTENT_TEXT_PLAIN,"dlx test...".getBytes());
    }
}
消费者类：

package com.mq.test;

import com.mq.test.config.RabbitmqConfig;
import com.rabbitmq.client.*;

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

/**
 * Created by Administrator on 2018/6/7.
 */
public class MqConsumerTest {
    private final static String DLX_EXCHANGE_NAME = "dlx_exchange";
    private final static String NORMAL_EXCHANGE_NAME = "normal_exchange";
    private final static String DLX_ROUTINGKEY = "dlx";
    private final static String NORMAL_ROUTINGKEY = "normal";
    private final static String DLX_QUEUE = "dlx";
    private final static String NORMAL_QUEUE = "normal";

    public static void main(String[] args) throws IOException {
        final Channel channel = RabbitmqConfig.getChannel();
        //创建正常队列和绑定，带参数的
        Map<String, Object> arguments = new HashMap<String, Object>();
        arguments.put("x-dead-letter-exchange", DLX_EXCHANGE_NAME);
        arguments.put("x-dead-letter-routing-key", DLX_ROUTINGKEY);
        arguments.put("x-message-ttl",6000);//如果想实现延迟队列的功能可以设置，只要消息在队列达到设定的这个时间没有被消费，就自动发送到死信队列，注意这里是消息未被消费，而不是未被ack!!!
        channel.queueDeclare(NORMAL_QUEUE, true, false, false, arguments);
        channel.queueBind(NORMAL_QUEUE, NORMAL_EXCHANGE_NAME, NORMAL_ROUTINGKEY);
        //创建死信队列和绑定
        channel.queueDeclare(DLX_QUEUE, true, false, false, null);
        channel.queueBind(DLX_QUEUE, DLX_EXCHANGE_NAME, DLX_ROUTINGKEY);
        channel.basicQos(64);
        channel.basicConsume(NORMAL_QUEUE, false, "myConsumerTag", new Consumer() {
            @Override
            public void handleConsumeOk(String s) {

            }

            @Override
            public void handleCancelOk(String s) {

            }

            @Override
            public void handleCancel(String s) throws IOException {

            }

            @Override
            public void handleShutdownSignal(String s, ShutdownSignalException e) {

            }

            @Override
            public void handleRecoverOk(String s) {

            }

            @Override
            public void handleDelivery(String s, Envelope envelope, AMQP.BasicProperties basicProperties, byte[] bytes) throws IOException {
                String routingKey = envelope.getRoutingKey();
                String contentType = basicProperties.getContentType();
                long deliveryTag = envelope.getDeliveryTag();
                try {
                    Thread.sleep(8000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
//                channel.basicReject(deliveryTag,false);
            }
        });
    }
}
延时或是死信队列实现：

package com.mq.test;

import com.mq.test.config.RabbitmqConfig;
import com.rabbitmq.client.*;

import java.io.IOException;

/**
 * Created by Administrator on 2018/6/7.
 */
public class MqdeplayQueueTest {
    private final static String DLX_QUEUE = "dlx";
    public static void main(String[] args) throws IOException {
        final Channel channel = RabbitmqConfig.getChannel();
        channel.basicConsume(DLX_QUEUE, true, "myDlxConsumer", new Consumer() {
            @Override
            public void handleConsumeOk(String s) {

            }

            @Override
            public void handleCancelOk(String s) {

            }

            @Override
            public void handleCancel(String s) throws IOException {

            }

            @Override
            public void handleShutdownSignal(String s, ShutdownSignalException e) {

            }

            @Override
            public void handleRecoverOk(String s) {

            }

            @Override
            public void handleDelivery(String s, Envelope envelope, AMQP.BasicProperties basicProperties, byte[] bytes) throws IOException {
                long deliveryTag = envelope.getDeliveryTag();
                System.out.println("这是延迟队列收到的消息："+new String(bytes));
            }
        });
    }
}

这就是全部的代码，欢迎大家交流！