如果希望消息被所有的訂閱者消費，可以使用廣播機制。

生產者

package com.yunsheng.broadcast;

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

public class BroadcastProducer {
    public static void main(String[] args) throws Exception {
        DefaultMQProducer producer = new DefaultMQProducer("ProducerGroupName");
        producer.setNamesrvAddr("10.135.17.26:9876;10.135.17.27:9876");
        producer.start();

        for (int i = 0; i < 10; i++) {
            Message msg = new Message("broadcastTopic",
                    "TagA",
                    "OrderID188",
                    "Hello world".getBytes());
            SendResult sendResult = producer.send(msg);
            System.out.printf("%s%n", sendResult);
        }
        producer.shutdown();
    }
}

producer就是最簡單的發送代碼。

消費者

package com.yunsheng.broadcast;

import com.alibaba.rocketmq.client.consumer.DefaultMQPushConsumer;
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.consumer.ConsumeFromWhere;
import com.alibaba.rocketmq.common.message.MessageExt;
import com.alibaba.rocketmq.common.protocol.heartbeat.MessageModel;

import java.util.List;

public class BroadcastConsumer1 {
    public static void main(String[] args) throws Exception {
        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("example_group_name");
        consumer.setNamesrvAddr("10.135.17.26:9876;10.135.17.27:9876");
        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);

        //set to broadcast mode
        consumer.setMessageModel(MessageModel.BROADCASTING);

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

        consumer.registerMessageListener(new MessageListenerConcurrently() {

            public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs,
                                                            ConsumeConcurrentlyContext context) {
                System.out.printf(Thread.currentThread().getName() + " Receive New Messages: " + msgs + "%n");
                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
            }
        });

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

再復制一份作BroadcastConsumer2

測試

啟動BroadcastConsumer1，BroadcastConsumer2，BroadcastProducer。
可以看到兩個consumer都消費了10個消息。

將consumer的consumer.setMessageModel(MessageModel.BROADCASTING);注釋掉。
再測試一次，可以發現兩個consumer分別消費了部分消息。