(转载)【RocketMQ 课程笔记】12.RocketMQ发送消息之有序消息

RocketMQ发送消息之有序消息

假设没有分区时有什么问题？
如果某一笔业务产分为多条普通消息同时发送，消费者无法保证按按生产者预期的顺序进行消费，进而导致代码逻辑错误。

分区有序消息

分区有序消息：与Kafka中的分区类似，把一个Topic消息分为多个分区“保存”和消费，在一个分区内的消息就是传统的队列，遵循FIFO（先进先出）原则。
全局有序消息：如果把一个 Topic 的分区数设置为 1，那么该 Topic 中的消息就是单分区，所有消息都遵循FIFO（先进先出）的原则。

Consumer消费时通过一个分区只能有一个线程消费的方式来保证消息顺序。

部署拓扑

源码讲解

pom.xml

<dependency>
    <groupId>org.apache.rocketmq</groupId>
    <artifactId>rocketmq-client</artifactId>
    <version>4.9.2</version>
</dependency>

MessageType2

package com.itlaoqi.rocketmq.mtype;
...
import java.util.List;
@Slf4j
//发送分区顺序消息
public class MessageType2 {
    public static void main(String[] args) {
        DefaultMQProducer producer = new DefaultMQProducer("ProducerGroupName");
        producer.setNamesrvAddr("192.168.31.103:9876");
        producer.setRetryTimesWhenSendAsyncFailed(2);
        try {
            producer.start();
            Integer id = 4465;
            String data = "{\"id\":" + id+" , + \"title\":\"X市2021年度第四季度税务汇总数据\"}";
            Message message = new Message("tax-data", "2021S4",id.toString(),
            data.getBytes(RemotingHelper.DEFAULT_CHARSET));
            //分区有序消息最大的区别便是调用send方法是，需要实现MessageQueueSelector接口，确定使用哪个队列投递消息
            SendResult result = producer.send(message, new MessageQueueSelector() {
                @Override
                public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
                log.info("当前队列数量：" + mqs.size() + ",明细：" + mqs.toString());
                log.info("Message对象：" + msg.toString());
                int dataId = Integer.parseInt(msg.getKeys());
                int index = dataId % mqs.size();
                MessageQueue messageQueue = mqs.get(index);
                log.info("分区队列:" + messageQueue);
                return messageQueue;
                }
            },null);
            
            log.info("消息已发送：MsgId:" + result.getMsgId() + "，发送状态:" + result.getSendStatus());
        }catch (Exception e){
        	e.printStackTrace();
        }finally {
            try {
                producer.shutdown();
                System.out.println("连接已关闭");
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }
}

输出结果

15:04:49.407 [main] INFO com.itlaoqi.rocketmq.mtype.MessageType2 - 当前队列数量：4,明细：[MessageQueue [topic=tax-data, brokerName=broker-a, queueId=0], MessageQueue[topic=tax-data, brokerName=broker-a, queueId=1], MessageQueue [topic=tax-data,brokerName=broker-a, queueId=2], MessageQueue [topic=tax-data, brokerName=brokera, queueId=3]]
15:04:49.409 [main] INFO com.itlaoqi.rocketmq.mtype.MessageType2 - Message对象：Message{topic='tax-data', flag=0, properties={KEYS=4465, WAIT=true, TAGS=2021S4},body=[123, 34, 105, 100, 34, 58, 52, 52, 54, 53, 32, 44, 32, 43, 32, 34, 116, 105, 116, 108, 101, 34, 58, 34, 88, -27, -72, -126, 50, 48, 50, 49, -27, -71, -76, -27, -70, -90, -25, -84, -84, -27, -101, -101, -27, -83, -93, -27, -70, -90, -25, -88, -114, -27, -118, -95, -26, -79, -121, -26, -128, -69, -26, -107, 80, -26, -115, -82, 34, 125], transactionId='null'}
15:04:49.409 [main] INFO com.itlaoqi.rocketmq.mtype.MessageType2 - 分区队列:MessageQueue [topic=tax-data, brokerName=broker-a, queueId=1]
15:04:49.712 [main] INFO com.itlaoqi.rocketmq.mtype.MessageType2 - 消息已发送：MsgId:7F0000013C4018B4AAC20D891D290000，发送状态:SEND_OK

全局有序消息

代码解析
在实现MessageQueueSelector接口时，固定选择某个队列就代表全局有序。注意：这里的全局有序代表broker中全局有序。如果消息被分发到不同的broker中，不保证有序，当然这种使用方法是错误的。

SendResult result = producer.send(message, new MessageQueueSelector() {
    @Override
    public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
        MessageQueue messageQueue = mqs.get(0);
        return messageQueue;
    }
},id);

输出结果

15:08:18.295 [main] INFO com.itlaoqi.rocketmq.mtype.MessageType2 - 当前队列数量：4,明细：[MessageQueue [topic=tax-data, brokerName=broker-a, queueId=0], MessageQueue [topic=tax-data, brokerName=broker-a, queueId=1], MessageQueue [topic=tax-data, brokerName=broker-a, queueId=2], MessageQueue [topic=tax-data, brokerName=brokera, queueId=3]]
15:08:18.297 [main] INFO com.itlaoqi.rocketmq.mtype.MessageType2 - Message对象：Message{topic='tax-data', flag=0, properties={KEYS=4465, WAIT=true, TAGS=2021S4}, body=[123, 34, 105, 100, 34, 58, 52, 52, 54, 53, 32, 44, 32, 43, 32, 34, 116, 105, 116, 108, 101, 34, 58, 34, 88, -27, -72, -126, 50, 48, 50, 49, -27, -71, -76, -27, -70, -90, -25, -84, -84, -27, -101, -101, -27, -83, -93, -27, -70, -90, -25, -88, -114, -27, -118, -95, -26, -79, -121, -26, -128, -69, -26, -107, -80, -26, -115, -82, 34, 125], transactionId='null'}
15:08:18.297 [main] INFO com.itlaoqi.rocketmq.mtype.MessageType2 - 分区队列:MessageQueue [topic=tax-data, brokerName=broker-a, queueId=0]
15:08:18.602 [main] INFO com.itlaoqi.rocketmq.mtype.MessageType2 - 消息已发送：MsgId:7F00000134C418B4AAC20D8C4D220000，发送状态:SEND_OK