五分钟带你玩转rocketMQ（六）队列难题——如何顺序消费

现在我们想按照顺序消费消息

顺序消费场景：因为rocketmq有多个队列，所以当多个业务 如 登陆 下单 发货 使用rocketmq时，需要按照这个顺序进行消费，所以解决途径就是 使用MessageQueueSelector 将同一个批次的业务同步放入一个队列 然后顺序消费就可以了。

先原有基础上

1.修改消费者

package cn.baocl.rocketmq.processor;


import com.alibaba.rocketmq.client.consumer.listener.ConsumeOrderlyContext;
import com.alibaba.rocketmq.client.consumer.listener.ConsumeOrderlyStatus;
import com.alibaba.rocketmq.client.consumer.listener.MessageListenerOrderly;
import com.alibaba.rocketmq.common.message.MessageExt;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicLong;

@Component
public class MQConsumeMsgListenerProcessor implements MessageListenerOrderly {
    private static final Logger logger = LoggerFactory.getLogger(MQConsumeMsgListenerProcessor.class);

    @Override
    public ConsumeOrderlyStatus consumeMessage(List<MessageExt> list, ConsumeOrderlyContext context) {
        //原子类 可以使消费者同步进行
        AtomicLong consumeTimes = new AtomicLong(0);
        context.setAutoCommit(false);
        consumeTimes.incrementAndGet();
        if ((consumeTimes.get() % 2) == 0) {
            return ConsumeOrderlyStatus.SUCCESS;
        } else if ((consumeTimes.get() % 3) == 0) {
            return ConsumeOrderlyStatus.ROLLBACK;
        } else if ((consumeTimes.get() % 4) == 0) {
            return ConsumeOrderlyStatus.COMMIT;
        } else if ((consumeTimes.get() % 5) == 0) {
            context.setSuspendCurrentQueueTimeMillis(3000);
            return ConsumeOrderlyStatus.SUSPEND_CURRENT_QUEUE_A_MOMENT;
        }
        return ConsumeOrderlyStatus.SUCCESS;
    }


}

2.修改调用方法

package cn.baocl.rocketmq.controllor;

import cn.baocl.rocketmq.entity.TestVo;
import com.alibaba.rocketmq.client.exception.MQBrokerException;
import com.alibaba.rocketmq.client.exception.MQClientException;
import com.alibaba.rocketmq.client.producer.DefaultMQProducer;
import com.alibaba.rocketmq.client.producer.MessageQueueSelector;
import com.alibaba.rocketmq.client.producer.SendCallback;
import com.alibaba.rocketmq.client.producer.SendResult;
import com.alibaba.rocketmq.common.message.Message;
import com.alibaba.rocketmq.common.message.MessageQueue;
import com.alibaba.rocketmq.remoting.common.RemotingHelper;
import com.alibaba.rocketmq.remoting.exception.RemotingException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.List;


@RestController
@RequestMapping("/test")
public class TestControllor {
    private static final Logger logger = LoggerFactory.getLogger(TestControllor.class);

    /**
     * 使用RocketMq的生产者
     */
    @Resource(name = "customRocketMQProducer")
    private DefaultMQProducer producer;

    @RequestMapping("/send")
    public void send() throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
        //定义tags
        String[] tags = new String[] {"TagA", "TagB", "TagC", "TagD", "TagE"};
        for (int i = 0; i < 100; i++) {
            int orderId = i % 10;
            //指定每条消息发送到某个tags
            Message msg = new Message("DemoTopic", tags[i % tags.length], "KEY" + i,
                    ("现在排号到:" + i).getBytes());
            //顺序发送方法
            SendResult sendResult = producer.send(msg, new MessageQueueSelector() {
                @Override
                public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
                    Integer id = (Integer) arg;
                    int index = id % mqs.size();
                    return mqs.get(index);
                }
            }, orderId);
            //orderId 就是队列编号 ，默认有4个队列
            System.out.print("此条消息id为:"+i);
            System.out.printf("%s%n", sendResult);
        }
    }
}

得到的结果是A,B,C,D,E tags每个都是按照顺序消费的