rocketmq支持有序的发送消息，有序的消费消息，这里便来看一下如何实现？
实战方面均以
RocketMQTemplate形式展现，集成方案详见《springboot中rocketmq的集成与使用》
消息的有序发送方面，我们可以直接使用syncSendOrderly（同步有序发送）和asyncSendOrderly（异步有序发送）两种类型的方法进行发送消息，他们的区别就如命名一样是同步和异步的区别。
下面给出同步有序发送的样例代码：
public class OrderProducer {
private static final Integer NUM = 10;
@Resource
private RocketMQTemplate rocketMQTemplate;
public void sendSyncOrderly() {
String message = "orderly message: ";
for (int i = 0; i < NUM; i++) {
// 模拟有序发送消息
rocketMQTemplate.syncSendOrderly("topic-orderly", message + i, "select_queue_key");
}
}
}
有序消息的发送比普通消息的发送多了一类参数“select_queue_key”，在rocketmq-spring中叫做hashKey，该参数的左右即是在发送消息的时候，固定发送到一个队列（默认情况下rocketmq中的topic有4个队列）以保证顺序。
有序消费的样例代码如下：
@Slf4j
@RocketMQMessageListener(topic = "topic-orderly",
consumerGroup = "orderly-consumer-group",consumeMode = ConsumeMode.ORDERLY)
public class OrderConsumer implements RocketMQListener<String> {
@Override
public void onMessage(String message) {
log.info("========{}=======", message);
}
}
这里主要是设置消费模式consumeMode = ConsumeMode.ORDERLY，默认情况下是并发消费模式（ConsumeMode.CONCURRENTLY）。
2019-10-22 21:59:01.654 INFO 1400 --- [ main] c.l.s.r.SpringbootAcRocketmqApplication : Started SpringbootAcRocketmqApplication in 2.611 seconds (JVM running for 3.824)
2019-10-22 21:59:04.474 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 0=======
2019-10-22 21:59:04.475 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD27200000 cost: 0 ms
2019-10-22 21:59:04.475 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 1=======
2019-10-22 21:59:04.475 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD27280002 cost: 0 ms
2019-10-22 21:59:04.476 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 2=======
2019-10-22 21:59:04.476 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD272A0004 cost: 0 ms
2019-10-22 21:59:04.476 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 3=======
2019-10-22 21:59:04.476 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD272C0006 cost: 0 ms
2019-10-22 21:59:04.476 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 4=======
2019-10-22 21:59:04.476 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD272D0008 cost: 0 ms
2019-10-22 21:59:04.476 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 5=======
2019-10-22 21:59:04.476 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD272F000A cost: 0 ms
2019-10-22 21:59:04.477 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 6=======
2019-10-22 21:59:04.477 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD2731000C cost: 0 ms
2019-10-22 21:59:04.477 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 7=======
2019-10-22 21:59:04.477 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD2733000E cost: 0 ms
2019-10-22 21:59:04.477 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 8=======
2019-10-22 21:59:04.477 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD27350010 cost: 0 ms
2019-10-22 21:59:04.478 INFO 1400 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 9=======
2019-10-22 21:59:04.478 INFO 1400 --- [MessageThread_1] a.r.s.s.DefaultRocketMQListenerContainer : consume C0A801040578512DDF1770DD27360012 cost: 0 ms
如果消费者不设置为有序消费的话，则消费的消息则是乱序的：
2019-10-22 22:00:59.922 INFO 2198 --- [MessageThread_2] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 1=======
2019-10-22 22:00:59.926 INFO 2198 --- [MessageThread_8] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 7=======
2019-10-22 22:00:59.922 INFO 2198 --- [MessageThread_6] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 5=======
2019-10-22 22:00:59.922 INFO 2198 --- [MessageThread_3] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 2=======
2019-10-22 22:00:59.922 INFO 2198 --- [MessageThread_1] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 0=======
2019-10-22 22:00:59.925 INFO 2198 --- [MessageThread_4] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 3=======
2019-10-22 22:00:59.926 INFO 2198 --- [MessageThread_7] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 6=======
2019-10-22 22:00:59.927 INFO 2198 --- [MessageThread_9] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 8=======
2019-10-22 22:00:59.925 INFO 2198 --- [MessageThread_5] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 4=======
2019-10-22 22:00:59.927 INFO 2198 --- [essageThread_10] c.l.sbac.rocketmq.order.OrderConsumer : ========orderly message: 9=======