RocketMQ使用FIFO队列提供有序消息.

以下示例演示发送/接收全局和分区有序消息。

发送消息示例代码

[code lang=”java”]
public class OrderedProducer {
public static void main(String[] args) throws Exception {
//Instantiate with a producer group name.
MQProducer producer = new DefaultMQProducer("example_group_name");
//Launch the instance.
producer.start();
String[] tags = new String[] {"TagA", "TagB", "TagC", "TagD", "TagE"};
for (int i = 0; i < 100; i++) {
int orderId = i % 10;
//Create a message instance, specifying topic, tag and message body.
Message msg = new Message("TopicTestjjj", tags[i % tags.length], "KEY" + i,
("Hello RocketMQ " + i).getBytes(RemotingHelper.DEFAULT_CHARSET));
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.printf("%s%n", sendResult);
}
//server shutdown
producer.shutdown();
}
}
[/code]

订阅消息简单示例代码

[code lang=”java”]
public class OrderedConsumer {
public static void main(String[] args) throws Exception {
DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("example_group_name");

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.printf(Thread.currentThread().getName() + " Receive New Messages: " + msgs + "%n");
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.printf("Consumer Started.%n");
}
}
[/code]