原文链接 译者:小村长
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
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(); } }
订阅消息简单示例代码
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"); } }