51.RocketMQ 顺序消费

大部分的员工早上的心情可能不会很好，因为这时想到还有很多事情要做，压力会大点，一般到下午4点左右，状态会是一天中最好的，因为这时大部分的工作做得差不多了，又快要下班了，当然也不是绝对。要注意记录各下属一天中状态最好的时间，好展开工作

3种不同模式的Producer

• NormalProducer（普通）
• OrderProducer（顺序）
• TransactionProducer（事务）

生产者

 /**
  * Copyright (C) 2010-2013 Alibaba Group Holding Limited
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package com.alibaba.rocketmq.example.ordermessage;

 import java.util.List;

 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.MQProducer;
 import com.alibaba.rocketmq.client.producer.MessageQueueSelector;
 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.exception.RemotingException;

 /**
  * Producer，发送顺序消息
  */
 public class Producer {
     public static void main(String[] args) {
         try {
             MQProducer producer = new DefaultMQProducer("please_rename_unique_group_name");

             producer.start();

             String[] tags = new String[] { "TagA", "TagB", "TagC", "TagD", "TagE" };

             for (int i = 0; i < 100; i++) {
                 // 订单ID相同的消息要有序
                 int orderId = i % 10;
                 Message msg = new Message("TopicTestjjj", tags[i % tags.length], "KEY" + i,
                     ("Hello RocketMQ " + i).getBytes());

                 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);

                 System.out.println(sendResult);
             }

             producer.shutdown();
         }
         catch (MQClientException e) {
             e.printStackTrace();
         }
         catch (RemotingException e) {
             e.printStackTrace();
         }
         catch (MQBrokerException e) {
             e.printStackTrace();
         }
         catch (InterruptedException e) {
             e.printStackTrace();
         }
     }
 }

消费者，只允许有一个线程在接收消息，因为broker只保证是顺序到达，不保证在消费的时候也能顺序消费。

 /**
  * Copyright (C) 2010-2013 Alibaba Group Holding Limited
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package com.alibaba.rocketmq.example.ordermessage;

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

 import com.alibaba.rocketmq.client.consumer.DefaultMQPushConsumer;
 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.client.exception.MQClientException;
 import com.alibaba.rocketmq.common.consumer.ConsumeFromWhere;
 import com.alibaba.rocketmq.common.message.MessageExt;

 /**
  * 顺序消息消费，带事务方式（应用可控制Offset什么时候提交）
  */
 public class Consumer {

     public static void main(String[] args) throws MQClientException {
         DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("please_rename_unique_group_name_3");
         /**
          * 设置Consumer第一次启动是从队列头部开始消费还是队列尾部开始消费<br>
          * 如果非第一次启动，那么按照上次消费的位置继续消费
          */
         consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);

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

         consumer.registerMessageListener(new MessageListenerOrderly() {
             AtomicLong consumeTimes = new AtomicLong(0);

             @Override
             public ConsumeOrderlyStatus consumeMessage(List<MessageExt> msgs, ConsumeOrderlyContext context) {
                 context.setAutoCommit(false);
                 System.out.println(Thread.currentThread().getName() + " Receive New Messages: " + msgs);
                 this.consumeTimes.incrementAndGet();
                 if ((this.consumeTimes.get() % 2) == 0) {
                     return ConsumeOrderlyStatus.SUCCESS;
                 }
                 else if ((this.consumeTimes.get() % 3) == 0) {
                     return ConsumeOrderlyStatus.ROLLBACK;
                 }
                 else if ((this.consumeTimes.get() % 4) == 0) {
                     return ConsumeOrderlyStatus.COMMIT;
                 }
                 else if ((this.consumeTimes.get() % 5) == 0) {
                     context.setSuspendCurrentQueueTimeMillis(3000);
                     return ConsumeOrderlyStatus.SUSPEND_CURRENT_QUEUE_A_MOMENT;
                 }

                 return ConsumeOrderlyStatus.SUCCESS;
             }
         });

         consumer.start();

         System.out.println("Consumer Started.");
     }

 }