顺序消息的概念

消息有序指的是可以按照消息的发送顺序来消费(FIFO)。

RocketMQ可以严格的保证消息有序，可以分为分区有序或者全局有序。

顺序消费的原理

在默认的情况下消息发送会采取Round Robin轮询方式把消息发送到不同的queue(分区队列)；

而消费消息的时候从多个queue上拉取消息，这种情况发送和消费是不能保证顺序。

但是如果控制发送的顺序消息只依次发送到同一个queue中，消费的时候只从这个queue上依次拉取，则就保证了顺序。

当发送和消费参与的queue只有一个，则是全局有序；如果多个queue参与，则为分区有序，即相对每个queue，消息都是有序的。

消费状态

 

package org.apache.rocketmq.client.consumer.listener;

public enum ConsumeOrderlyStatus {
    /**
     * Success consumption
     */
    SUCCESS,

    /**
     * Suspend current queue a moment
     * 不能跳过消息，等待一下
     */
    SUSPEND_CURRENT_QUEUE_A_MOMENT;
}

演示

下面用订单进行分区有序的示例。一个订单的顺序流程是：创建、付款、推送、完成。订单号相同的消息会被先后发送到同一个队列中，消费时，同一个OrderId获取到的肯定是同一个队列。

Producer

package com.artisan.rocketmq.order;

import org.apache.rocketmq.client.producer.DefaultMQProducer;
import org.apache.rocketmq.client.producer.MessageQueueSelector;
import org.apache.rocketmq.client.producer.SendResult;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageQueue;
import org.apache.rocketmq.remoting.common.RemotingHelper;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 16:38
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/

public class OrderedProducer {

    public static void main(String[] args) throws Exception {
        DefaultMQProducer producer = new DefaultMQProducer("ordered_group_name");

        producer.setNamesrvAddr("192.168.18.130:9876;192.168.18.131:9876");

        producer.start();

        String[] tags = new String[]{"TagA", "TagC", "TagD"};

        // 订单列表
        List<OrderStep> orderList = buildOrders();

        Date date = new Date();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String dateStr = sdf.format(date);
        for (int i = 0; i < 10; i++) {
            // 加个时间前缀
            String body = dateStr + " Hello RocketMQ "+ i + " " + orderList.get(i);
            Message msg = new Message("TopicTest", tags[i % tags.length], "KEY" + i,
                    body.getBytes(RemotingHelper.DEFAULT_CHARSET));

            SendResult sendResult = producer.send(msg, new MessageQueueSelector() {
                @Override
                public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
                    Long id = (Long) arg;  //根据订单id选择发送queue
                    long index = id % mqs.size();
                    return mqs.get((int) index);
                }
            }, orderList.get(i).getOrderId());//订单id

            System.out.println(String.format("SendResult status:%s, queueId:%d, body:%s",
                    sendResult.getSendStatus(),
                    sendResult.getMessageQueue().getQueueId(),
                    body));
        }

        producer.shutdown();
    }


    /**
     * 生成模拟订单数据
     */
    private static List<OrderStep> buildOrders() {
        List<OrderStep> orderList = new ArrayList<OrderStep>();

        OrderStep orderDemo = new OrderStep();
        orderDemo.setOrderId(15103111039L);
        orderDemo.setDesc("创建");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103111065L);
        orderDemo.setDesc("创建");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103111039L);
        orderDemo.setDesc("付款");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103117235L);
        orderDemo.setDesc("创建");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103111065L);
        orderDemo.setDesc("付款");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103117235L);
        orderDemo.setDesc("付款");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103111065L);
        orderDemo.setDesc("完成");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103111039L);
        orderDemo.setDesc("推送");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103117235L);
        orderDemo.setDesc("完成");
        orderList.add(orderDemo);

        orderDemo = new OrderStep();
        orderDemo.setOrderId(15103111039L);
        orderDemo.setDesc("购物车");
        orderList.add(orderDemo);

        return orderList;
    }

    /**
     * 订单的步骤
     */
    private static class OrderStep {
        private long orderId;
        private String desc;

        public long getOrderId() {
            return orderId;
        }

        public void setOrderId(long orderId) {
            this.orderId = orderId;
        }

        public String getDesc() {
            return desc;
        }

        public void setDesc(String desc) {
            this.desc = desc;
        }

        @Override
        public String toString() {
            return "OrderStep{" +
                    "orderId=" + orderId +
                    ", desc='" + desc + '\'' +
                    '}';
        }
    }
}

日志
在这里插入图片描述

Consumer

package com.artisan.rocketmq.order;

import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer;
import org.apache.rocketmq.client.consumer.listener.ConsumeOrderlyContext;
import org.apache.rocketmq.client.consumer.listener.ConsumeOrderlyStatus;
import org.apache.rocketmq.client.consumer.listener.MessageListenerOrderly;
import org.apache.rocketmq.common.consumer.ConsumeFromWhere;
import org.apache.rocketmq.common.message.MessageExt;
import org.apache.rocketmq.remoting.common.RemotingHelper;

import java.io.UnsupportedEncodingException;
import java.util.List;
import java.util.Random;
import java.util.concurrent.TimeUnit;

/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 16:38
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/

public class OrderedConsumer {
    public static void main(String[] args) throws Exception {
        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("ordered_group_name");
        consumer.setNamesrvAddr("192.168.18.130:9876;192.168.18.131:9876");
        /**
         * 设置消费位置
         */
        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);

        consumer.subscribe("TopicTest", "*");
        // 有序消费 MessageListenerOrderly
        consumer.registerMessageListener(new MessageListenerOrderly() {

            @Override
            public ConsumeOrderlyStatus consumeMessage(List<MessageExt> msgs,
                                                       ConsumeOrderlyContext context) {
                context.setAutoCommit(true);
                Random random = new Random();
                for (MessageExt msg : msgs) {
                    // 可以看到每个queue有唯一的consume来消费, 订单对每个queue(分区)有序
                    try {
                        System.out.println("consumeThread=" + Thread.currentThread().getName()
                                + ", queueId=" + msg.getQueueId()
                                + ", content:" + new String(msg.getBody(),
                                RemotingHelper.DEFAULT_CHARSET));
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }
                }

                try {
                    //模拟业务逻辑处理中...
                    TimeUnit.SECONDS.sleep(random.nextInt(10));
                } catch (Exception e) {
                    e.printStackTrace();
                }
                return ConsumeOrderlyStatus.SUCCESS;

            }
        });

        consumer.start();

        System.out.printf("Consumer Started.%n");
    }
}