RocketMQ快速入門詳解

 RocketMQ是阿里巴巴在2012年開源的分佈式消息中間件，目前已經捐贈給Apache基金會，已經於2016年11月成爲 Apache 孵化項目，相信RocketMQ的未來會發揮着越來越大的作用，將有更多的開發者因此受益。

        本文僅對RocketMQ的簡單實用做入門性介紹，不對RocketMQ的底層原理進行深入介紹，後續文章將對RocketMQ的原理做詳細介紹。

        RocketMQ的Maven依賴：

   

<!-- https://mvnrepository.com/artifact/com.alibaba.rocketmq/rocketmq-client -->
<dependency>
    <groupId>com.alibaba.rocketmq</groupId>
    <artifactId>rocketmq-client</artifactId>
    <version>3.2.6</version>
</dependency>

     MQ的消費類RocketMQConsumer.java：

    

package com.lance.rocketMQ.RocketMQ;

import com.alibaba.rocketmq.client.consumer.DefaultMQPushConsumer;
import com.alibaba.rocketmq.client.consumer.listener.MessageListener;
import com.alibaba.rocketmq.client.consumer.listener.MessageListenerConcurrently;
import com.alibaba.rocketmq.client.exception.MQClientException;
import com.alibaba.rocketmq.common.consumer.ConsumeFromWhere;

import java.util.UUID;


/**
 * Created by lance on 2017/2/10.
 */
public class RocketMQConsumer {

    private DefaultMQPushConsumer consumer;

    private MessageListener listener;

    protected String nameServer;

    protected String groupName;

    protected String topics;

    public RocketMQConsumer(MessageListener listener, String nameServer, String groupName, String topics) {
        this.listener = listener;
        this.nameServer = nameServer;
        this.groupName = groupName;
        this.topics = topics;
    }

    public void init() {
        consumer = new DefaultMQPushConsumer(groupName);
        consumer.setNamesrvAddr(nameServer);
        try {
            consumer.subscribe(topics, "*");
        } catch (MQClientException e) {
            e.printStackTrace();
        }
        consumer.setInstanceName(UUID.randomUUID().toString());
        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_LAST_OFFSET);
        consumer.registerMessageListener((MessageListenerConcurrently) this.listener);

        try {
            consumer.start();
        } catch (MQClientException e) {
            e.printStackTrace();
        }
        System.out.println("RocketMQConsumer Started! group=" + consumer.getConsumerGroup() + " instance=" + consumer.getInstanceName()
        );
    }


}

       MQ消息的監聽接口類RocketMQListener.java

      

        

package com.lance.rocketMQ.RocketMQ;

import com.alibaba.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext;
import com.alibaba.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus;
import com.alibaba.rocketmq.client.consumer.listener.MessageListenerConcurrently;
import com.alibaba.rocketmq.common.message.MessageExt;

import java.util.List;

/**
 * Created by lance on 2017/2/10.
 */
public class RocketMQListener  implements MessageListenerConcurrently {


    @Override
    public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeConcurrentlyContext context) {
//        System.out.println("get data from rocketMQ:" + msgs);
        for (MessageExt message : msgs) {

            String msg = new String(message.getBody());
            System.out.println("msg data from rocketMQ:" + msg);
        }

        return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
    }
}

        MQ消息的生產者類RocketMQProducer.java

package com.lance.rocketMQ.RocketMQ;

import com.alibaba.rocketmq.client.exception.MQClientException;
import com.alibaba.rocketmq.client.producer.DefaultMQProducer;
import com.alibaba.rocketmq.client.producer.SendResult;
import com.alibaba.rocketmq.client.producer.SendStatus;
import com.alibaba.rocketmq.common.message.Message;

import java.util.UUID;

/**
 * Created by lance on 2017/2/10.
 */
public class RocketMQProducer {

    private DefaultMQProducer sender;

    protected String nameServer;

    protected String groupName;

    protected String topics;

    public void init() {
        sender = new DefaultMQProducer(groupName);
        sender.setNamesrvAddr(nameServer);
        sender.setInstanceName(UUID.randomUUID().toString());
        try {
            sender.start();
        } catch (MQClientException e) {
            e.printStackTrace();
        }
    }

    public RocketMQProducer(String nameServer, String groupName, String topics) {
        this.nameServer = nameServer;
        this.groupName = groupName;
        this.topics = topics;
    }

    public void send(Message message) {

        message.setTopic(topics);

        try {
            SendResult result = sender.send(message);
            SendStatus status = result.getSendStatus();
            System.out.println("messageId=" + result.getMsgId() + ", status=" + status);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

       測試RocketMQ的消費 RocketMQConsumerTest.java

package com.lance.rocketMQ.RocketMQ;

/**
 * Created by lance on 2017/2/10.
 */
public class RocketMQConsumerTest {


    public static void main(String[] args) {


        String mqNameServer = "172.10.254.2:9876";
        String mqTopics = "MQ-MSG-TOPICS-TEST";

        String consumerMqGroupName = "CONSUMER-MQ-GROUP";
        RocketMQListener mqListener = new RocketMQListener();
        RocketMQConsumer mqConsumer = new RocketMQConsumer(mqListener, mqNameServer, consumerMqGroupName, mqTopics);
        mqConsumer.init();


        try {
            Thread.sleep(1000 * 60L);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

          run RocketMQConsumerTest.java 之後，控制檯輸出：

       

RocketMQConsumer Started! group=CONSUMER-MQ-GROUP instance=1eb7d308-4414-4658-90b5-e2cae3b793eb

            結果分析： 此時MQ對應的TOPIC中並沒有響應的消息，故收不到消息，僅看到MQ消費者正常啓動信息。

       

        MQ的生產者測試類:RocketMQProducerTest.java

       

package com.lance.rocketMQ.RocketMQ;

import com.alibaba.rocketmq.common.message.Message;

/**
 * Created by lance on 2017/2/10.
 */
public class RocketMQProducerTest {

    public static void main(String[] args) {

        String mqNameServer = "172.10.254.2:9876";
        String mqTopics = "MQ-MSG-TOPICS-TEST";

        String producerMqGroupName = "PRODUCER-MQ-GROUP";
        RocketMQProducer mqProducer = new RocketMQProducer(mqNameServer, producerMqGroupName, mqTopics);
        mqProducer.init();


        for (int i = 0; i < 5; i++) {

            Message message = new Message();
            message.setBody(("I send message to RocketMQ " + i).getBytes());
            mqProducer.send(message);
        }



    }

}

          run RocketMQProducerTest.java 之後，RocketMQProducerTest.java 對應的控制檯輸出爲：

                

messageId=0A71290100002A9F00000003D0BB0832, status=SEND_OK
messageId=0A71290100002A9F00000003D0BB08BB, status=SEND_OK
messageId=0A71290100002A9F00000003D0BB0944, status=SEND_OK
messageId=0A71290100002A9F00000003D0BB09CD, status=SEND_OK
messageId=0A71290300002A9F000000005440AEED, status=SEND_OK

         結果分析：表明所有消息都已經正常發送，且被RocketMQ正常接收。

          此時查看RocketMQConsumerTest.java對應的控制檯輸出發生改變，輸出內容變更如下:

         

RocketMQConsumer Started! group=CONSUMER-MQ-GROUP instance=1eb7d308-4414-4658-90b5-e2cae3b793eb
msg data from rocketMQ:I send message to RocketMQ 1
msg data from rocketMQ:I send message to RocketMQ 0
msg data from rocketMQ:I send message to RocketMQ 3
msg data from rocketMQ:I send message to RocketMQ 2
msg data from rocketMQ:I send message to RocketMQ 4

看，簡單吧！

備註：小編自己使用了Apache版本的RocketMQ(即RocketMQ 4.*)，發現只需要更改import的package的路徑而已，不需要修改其他代碼，請參考。

RocketMQ的重複問題解決方式：

a.MQ的消費端執行的操作具有冪等性，即無論多少次重複執行，其結果是一樣的；

b.MQ的消費端做重複校驗，比如將受到MQ消息的唯一編號保存到Redis中，即每次收到消息時，將檢查唯一編號是否已經在Redis中，如果存在說明消息重複；否則將唯一編號放入到Redis中，可以根據系統需要設置唯一編號在Redis中的過期時間，以防止Redis溢出。

 

參考鏈接：1.分佈式開放消息系統(RocketMQ)的原理與實踐 (強烈推薦)

                    2.RocketMQ捐贈給Apache那些鮮爲人知的故事