文章目录

广播消息
- 广播消息概述
- 演示步骤
延时消息
批量消息
- 批量消息概述
- 示例
代码

广播消息

广播消息概述

广播消息就是向所有用户发送消息。如果我们希望所有订阅者都能收到有关某个主题的消息，可以使用广播消息。

举个例子生产者发送10条消息，有2个订阅者，则这两个订阅者会分别收到10条消息，而与广播模式相对应的集群模式这是 2个订阅者一共收到10条消息。

Rocketmq 消费者默认是集群的方式消费的，使用广播模式进行消费需要显示设置

核心：消费端设置消息模型 consumer.setMessageModel(MessageModel.BROADCASTING);

演示步骤

启动2个或者2个以上的消费者
启动生产者发送消息
观察2个消费者的消息接收情况：两个Consumer收到了同样的消息，OK.

生产者：

package com.artisan.rocketmq.broadcast;

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;

/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 19:22
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/

public class BroadcastProducer {

    public static void main(String[] args) throws Exception {
        DefaultMQProducer producer = new DefaultMQProducer("consumer_model_group");
        producer.setNamesrvAddr("192.168.18.130:9876;192.168.18.131:9876");
        producer.start();

        for (int i = 0; i < 4; i++){
            Message msg = new Message("TopicTest",
                    "TagA",
                    "OrderID188",
                    ("Hello world"+i).getBytes(RemotingHelper.DEFAULT_CHARSET));
            SendResult sendResult = producer.send(msg);
            System.out.printf("%s%n", sendResult);
        }

        producer.shutdown();
    }
}

消费者：

package com.artisan.rocketmq.broadcast;

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.common.protocol.heartbeat.MessageModel;

import java.util.List;

/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 19:27
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/

public class BroadcastConsumer {

    public static void main(String[] args) throws Exception {
        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("consumer_model_group");
        consumer.setNamesrvAddr("192.168.18.130:9876;192.168.18.131:9876");
        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_LAST_OFFSET);
        //广播,全量消费
        consumer.setMessageModel(MessageModel.BROADCASTING);

        consumer.subscribe("TopicTest", "TagA || TagC || TagD");

        consumer.registerMessageListener(new MessageListenerConcurrently() {

            @Override
            public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs,
                                                            ConsumeConcurrentlyContext context) {
                for (MessageExt ext : msgs){
                    System.out.printf(Thread.currentThread().getName() + " Receive New Message: " + new String(ext.getBody()) + "%n");
                }
                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
            }
        });

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

测试结果：

生产者：

消费者1：

消费者2：

延时消息

概述

定时消息是指消息发到 Broker 后，不能立刻被 Consumer 消费，要到特定的时间点或者等待特定的时间后才能被消费。

使用场景

举个例子：电商系统，提交了一个订单就可以发送一个延时消息，1h后去检查这个订单的状态，如果还是未付款就取消订单释放库存。

延时机制

org.apache.rocketmq.store.config.MessageStoreConfig#messageDelayLevel

当前支持的延迟时间

1s 5s 10s 30s 1m 2m 3m 4m 5m 6m 7m 8m 9m 10m 20m 30m 1h 2h

分别对应级别

1 2 3....................

设置消息时延

Message message = new Message；
message.setDelayTimeLevel(3)

现在RocketMq并不支持任意时间的延时，需要设置几个固定的延时等级，从1s到2h分别对应着等级1到18 消息消费失败会进入延时消息队列，消息发送时间与设置的延时等级和重试次数有关。

实现原理

延迟队列的核心思路: 【利用中间队列临时存储】—>所有的延迟消息由producer消息发憷之后，都会存放在一个topic下（SHCEDULE_TOPIC_XXXX）, 不同的延迟级别对应不同的队列序号，当延迟时间到了之后，由定时线程读取转换为普通的消息存到真实指定的topic下，此时对于consumer端此消息才可见，从而被consumer消费。

示例

生产者：

package com.artisan.rocketmq.schedule;

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

import java.util.Date;

/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 17:23
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/

public class ScheduledMessageProducer {

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

        DefaultMQProducer producer = new DefaultMQProducer("ExampleConsumer");

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

        producer.start();
        int totalMessagesToSend = 3;
        for (int i = 0; i < totalMessagesToSend; i++) {
            Message message = new Message("TestTopic", ("Hello scheduled message " + i).getBytes());
            //延时消费  6-->2分钟
            message.setDelayTimeLevel(6);
            // Send the message
            producer.send(message);
        }

        System.out.printf("message send is completed .%n" + new Date());
        producer.shutdown();
    }
}

消费者：

package com.artisan.rocketmq.schedule;

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.message.MessageExt;

import java.util.Date;
import java.util.List;

/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 17:23
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/

public class ScheduledMessageConsumer {

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

        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("ExampleConsumer");
        consumer.setNamesrvAddr("192.168.18.130:9876;192.168.18.131:9876");

        consumer.subscribe("TestTopic", "*");

        consumer.registerMessageListener(new MessageListenerConcurrently() {
            @Override
            public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> messages, ConsumeConcurrentlyContext context) {
                for (MessageExt message : messages) {
                    // Print approximate delay time period
                    System.out.println(new Date() + "Receive message[msgId=" + message.getMsgId() + "] "
                            + "message content is :" + new String(message.getBody()));
                }
                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
            }
        });

        consumer.start();

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

设置的延迟level为6 ，对应的时间间隔是两分钟，OK。

批量消息

批量消息概述

批量发送消息能显著提高传递小消息的性能。限制是这些批量消息应该有相同的topic，相同的waitStoreMsgOK，而且不能是延时消息

此外，这一批消息的总大小不应超过4MB。rocketmq建议每次批量消息大小大概在1MB。当消息大小超过4MB时，需要将消息进行分割

示例

生产者

package com.artisan.rocketmq.batch;

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

import java.util.ArrayList;
import java.util.List;


/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 21:27
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/
public class BatchProducer {

    public static void main(String[] args) throws Exception {
        /**
         * rocketMq 支持消息批量发送
         * 同一批次的消息应具有：相同的主题，相同的waitStoreMsgOK，并且不支持定时任务。
         * <strong> 同一批次消息建议大小不超过~1M </strong>,消息最大不能超过4M,需要
         * 对msg进行拆分
         */
        DefaultMQProducer producer = new DefaultMQProducer("batch_group");
        producer.setNamesrvAddr("192.168.18.130:9876;192.168.18.131:9876");
        producer.start();

        String topic = "BatchTest";
        List<Message> messages = new ArrayList<>();
        messages.add(new Message(topic, "TagA", "OrderID001", "Hello world 0".getBytes()));
        messages.add(new Message(topic, "TagA", "OrderID002", "Hello world 1".getBytes()));
        messages.add(new Message(topic, "TagA", "OrderID003", "Hello world 2".getBytes()));

        ListSplitter splitter = new ListSplitter(messages);

        /**
         * 对批量消息进行拆分
         */
        while (splitter.hasNext()) {
            try {
                List<Message>  listItem = splitter.next();
                producer.send(listItem);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        producer.shutdown();

    }

}

消息拆分

package com.artisan.rocketmq.batch;

import org.apache.rocketmq.common.message.Message;

import java.util.Iterator;
import java.util.List;
import java.util.Map;


/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 21:35
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/
public class ListSplitter implements Iterator<List<Message>> {

    private final int SIZE_LIMIT = 1000 * 1000 * 1;//1MB
    private final List<Message> messages;
    private int currIndex;

    public ListSplitter(List<Message> messages) {
        this.messages = messages;
    }

    @Override
    public boolean hasNext() {
        return currIndex < messages.size();
    }

    @Override
    public List<Message> next() {
        int nextIndex = currIndex;
        int totalSize = 0;
        //遍历消息准备拆分
        for (; nextIndex < messages.size(); nextIndex++) {
            Message message = messages.get(nextIndex);
            int tmpSize = message.getTopic().length() + message.getBody().length;
            Map<String, String> properties = message.getProperties();
            for (Map.Entry<String, String> entry : properties.entrySet()) {
                tmpSize += entry.getKey().length() + entry.getValue().length();
            }
            tmpSize = tmpSize + 20; //for log overhead
            if (tmpSize > SIZE_LIMIT) {

                if (nextIndex - currIndex == 0) {
                    nextIndex++;
                }
                break;
            }
            if (tmpSize + totalSize > SIZE_LIMIT) {
                break;
            } else {
                totalSize += tmpSize;
            }

        }
        List<Message> subList = messages.subList(currIndex, nextIndex);
        currIndex = nextIndex;
        return subList;
    }
}

消费者

package com.artisan.rocketmq.batch;

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.client.exception.MQClientException;
import org.apache.rocketmq.common.message.MessageExt;

import java.util.List;


/**
 * @author 小工匠
 * @version v1.0
 * @create 2019-11-10 21:38
 * @motto show me the code ,change the word
 * @blog https://artisan.blog.csdn.net/
 * @description
 **/
public class Consumer {
    public static void main(String[] args) throws InterruptedException, MQClientException {

        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("batch_group");

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

        consumer.subscribe("BatchTest", "*");
        consumer.registerMessageListener(new MessageListenerConcurrently() {
            @Override
            public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs,
                                                            ConsumeConcurrentlyContext context) {
                for (MessageExt msg : msgs){
                    System.out.println("queueId=" + msg.getQueueId() + "," + new String(msg.getBody()));
                }
                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
            }
        });

        consumer.start();

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

代码

请移步： https://github.com/yangshangwei/rocketmqMaster

本文标题：RocketMQ-初体验RocketMQ(09)-广播消息、延时消息、批量消息

本文链接：https://blog.quwenai.cn/post/6341.html

作者授权：除特别说明外，本文由 toobug 原创编译并授权 TOOBUG信息安全网刊载发布。

本文链接：https://blog.quwenai.cn/post/6341.html

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正文

RocketMQ-初体验RocketMQ(09)-广播消息、延时消息、批量消息

文章目录

广播消息

广播消息概述

演示步骤

延时消息

概述

使用场景

延时机制

实现原理

示例

批量消息

批量消息概述

示例

代码

相关阅读

RocketMQ-延时消息Demo及实现原理分析

RocketMQ-初体验RocketMQ(01)_RocketMQ初体验

RocketMQ-初体验RocketMQ(11)-过滤消息_自定义Java类筛选消息

RocketMQ-初体验RocketMQ(03)_RocketMQ多机集群部署

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