RocketMQ 学习

1、MQ 主要由四个部分组成

　　producer consumer broker nameserver

boker为搬运工 nameserver为统一治理服务 producer consumer不必多说了一个生产者一个消费者

package com.jason.mq;

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

public class SyncProducer {

    public static void main(String[] args) throws Exception {

        DefaultMQProducer producer =
                new DefaultMQProducer("please_rename_unique_group_name");
        producer.setNamesrvAddr("127.0.0.1:9876");
        producer.start();

        for(int i = 0; i < 100; i++) {
           /* Message msg = new Message("TopicTest","TagA",
                    ("Hello RockerMQ " + i).getBytes(RemotingHelper.DEFAULT_CHARSET));
            SendResult sendResult = producer.send(msg);
            System.out.printf("%s%n", sendResult);*/

            Message message = new Message();
            message.setTopic("TopicTest");
            message.putUserProperty(i + "", "hello" + i);
            message.setBody((i +"**").getBytes(RemotingHelper.DEFAULT_CHARSET));
            SendResult sendResult = producer.send(message);
            System.out.println(sendResult);
        }
        producer.shutdown();


    }
}


以上是生产者 产生消息 发送到broker

package com.jason.mq;

import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer;
import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext;
import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus;
import org.apache.rocketmq.client.consumer.listener.MessageListenerConcurrently;
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;

public class SyncConsumer {
    public static void main(String[] args) throws Exception {

        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("please_rename_to_unique_group_name");
        consumer.setNamesrvAddr("127.0.0.1:9876");
        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);

        consumer.subscribe("TopicTest", "*");
        consumer.registerMessageListener(new MessageListenerConcurrently() {
            public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> list, ConsumeConcurrentlyContext consumeConcurrentlyContext) {

                for (MessageExt msg : list) {
                    try {
                        System.out.println("Receive properties: " + msg.getProperties());
                        System.out.println("Receive body: " + new String(msg.getBody(), RemotingHelper.DEFAULT_CHARSET));

                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }finally {
                        return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
                    }
                }


                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
            }
        });
        consumer.start();
    }
}

以上为消费者通过push  来进行获取信息

消费者分为 push pull 
区别是什么？你们知道么？
push一般用于没有慢消费到情况下（是broker主动push消息过去）  pull 一般主动权在消费者哪里（是消费者主动pull信息）
主动push的话，如果消费者消费过慢，那么在broker中会堆积消息过多，所以处理消费快的情况下使用
主动pull的情况下，可以根据具体情况，主动pull自己想要的信息,,这也是它的短板，因为消费方无法准确地决定何时去拉取最新的消息，一直消费，就要一直pull

根据实际情况选择吧。
我个人用push比较多

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