RabbitMQ消费端消息分发问题研究

一 先上思维导图

二 再看代码

1 生产者

package com.rabbitmq.basicqos;


import com.rabbitmq.client.Channel;
import com.rabbitmq.client.ConfirmListener;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.MessageProperties;
import com.rabbitmq.util.ConnectionUtils;
import lombok.extern.slf4j.Slf4j;


import java.io.IOException;
import java.util.Collections;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.TimeoutException;


import static com.rabbitmq.common.Constant.NUM64;


/**
* @className: QosProducer
* @description: Qos生产者
* @date: 2020/5/14
* @author: cakin
*/
@Slf4j
public class QosProducer {
    public static void main( String[] args ) throws IOException, TimeoutException {
        Connection connection = ConnectionUtils.getConnection();
        Channel channel = connection.createChannel();


        channel.exchangeDeclare("exchange.confirm", "direct", true, false, null);
        channel.queueDeclare("queue.basicqos", true, false, false, null);
        channel.queueBind("queue.basicqos", "exchange.confirm", "routingKey2");


        final SortedSet confirmSet = Collections.synchronizedNavigableSet(new TreeSet());
        // 启动confirm模式
        channel.confirmSelect();


        // 开启监听
        channel.addConfirmListener(new ConfirmListener() {
            // 处理成功
            public void handleAck( long deliveryTag, boolean multiple ) throws IOException {
                log.info("消息发送成功: " + deliveryTag
                        + ", multiple : " + multiple);
                // 收到消息，从消息序号队列中删除deliveryTag
                if (multiple) {
                    confirmSet.headSet(deliveryTag - 1).clear();
                } else {
                    confirmSet.remove(deliveryTag);
                }
            }


            // 处理失败
            public void handleNack( long deliveryTag, boolean multiple ) throws IOException {
                if (multiple) {
                    confirmSet.headSet(deliveryTag - 1).clear();
                } else {
                    confirmSet.remove(deliveryTag);
                }
            }
        });


        // 循环发送消息
        for (int i = 1; i < NUM64; i++) {
            String msg = "我是confirm模式消息.异步[" + i + "]";
            long tag = channel.getNextPublishSeqNo();
            // 发送消息，将deliveryTag加入到消息序号队列
            channel.basicPublish("exchange.confirm", "routingKey2", MessageProperties.PERSISTENT_TEXT_PLAIN, msg.getBytes());
            log.info("tag:" + tag);
            confirmSet.add(tag);
        }
    }
}

2 消费者

/**
* Copyright (C), 2020-2020, 软件公司
* FileName: RabbitConsumer.java
* Author:   cakin
* Date:     2020/5/2
* Description: 消费端
*/
package com.rabbitmq.basicqos;


import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Envelope;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.Consumer;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.util.ConnectionUtils;
import lombok.extern.slf4j.Slf4j;


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


import static com.rabbitmq.common.Constant.NUM5;


/**
* Qos测试的消费端
*/
@Slf4j
public class QosConsumer {
    /**
     * 消息队列
     */
    private static final String QUEUE_NAME = "queue.basicqos";


    /**
     * 控制ack消息
     */
    private static int num = 0;


    public static void main( String[] args ) {
        try {
            Connection connection = ConnectionUtils.getConnection();
            Channel channel = connection.createChannel();
            // 客户端最多未确认消息数为5，一旦超过5，客户端将无法接收到消息
            channel.basicQos(NUM5);
            Consumer consumer = new DefaultConsumer(channel) {
                @Override
                public void handleDelivery( String consumerTag,
                                            Envelope envelope,
                                            AMQP.BasicProperties properties,
                                            byte[] body )
                        throws IOException {
                    log.info(" recv message: " + new String(body));
                    // 控制是接收到的第几个消息
                    num++;
                    // 模拟业务处理耗时1秒
                    try {
                        TimeUnit.SECONDS.sleep(1);
                    } catch (InterruptedException e) {
                        log.info("catch InterruptedException");
                    }


                    // 只让是5的倍数的消息发ack消息
                    if (num % NUM5 == 0) {
                        channel.basicAck(envelope.getDeliveryTag(), false);
                    } else {
                        log.trace("模拟不发ack情况");
                        // channel.basicAck(envelope.getDeliveryTag(), false);
                    }
                }
            };
            channel.basicConsume(QUEUE_NAME, consumer);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (TimeoutException e) {
            e.printStackTrace();
        }
    }
}

三 运行说明

1 先运行生产者。

2 再运行消费者，消费者可以通过屏蔽和开启 channel.basicAck(envelope.getDeliveryTag(), false); 代码来观察运行结果，以此达到理解 channel.basicQos(NUM5); 目的。