public class Producer {
    public static void main(String[] args) throws UnsupportedEncodingException {
        try {
           // Instantiate a message producer.
            DefaultMQProducer producer = new DefaultMQProducer(groupName,
              // Access control list (ACL) permissions.
            new AclClientRPCHook(new SessionCredentials(ACCESS_KEY, SECRET_KEY)), true, null);
            // Set the NameServer address.
            producer.setNamesrvAddr("rmq-xxx.rocketmq.xxxtencenttdmq.com:8080");
            // Start the producer instance.
            producer.start();

            String[] tags = new String[] {"TagA", "TagB", "TagC", "TagD", "TagE"};
            for (int i = 0; i < 100; i++) {
                int orderId = i % 10;
                Message msg =
                    new Message("TopicTest", 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);
            }

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

public interface MessageQueueSelector {
    MessageQueue select(final List<MessageQueue> mqs, final Message msg, final Object arg);
}

/**
 * Description: Consumer of ordered messages.
 */
public class OrderConsumer {
    /**
     * Topic name.
     */
    private static final String TOPIC_NAME = "order_topic";

    /**
     * Consumer group name.
     */
    private static final String GROUP_NAME = "group2";
    public static void main(String[] args) throws Exception {
        // Create a message consumer.
        // Instantiate a consumer.
        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer(GROUP_NAME,
                new AclClientRPCHook(new SessionCredentials("accessKey", "secretKey")),
                new AllocateMessageQueueAveragely(), true, null);
        // Set the NameServer address.
        consumer.setNamesrvAddr("rmq-xxx.rocketmq.xxxtencenttdmq.com:8080");
        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);
        /*
         * Set whether the consumer starts consuming from the beginning or the end of the queue on its first startup.
         * If it is not the first startup, consumption continues from the last consumption position.
         */
        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);
        // Subscribe to all messages in the topic.
        consumer.subscribe(TOPIC_NAME, "*");
        consumer.registerMessageListener(new MessageListenerOrderly() {
            @Override
            public ConsumeOrderlyStatus consumeMessage(List<MessageExt> msgs, ConsumeOrderlyContext context) {
                context.setAutoCommit(true);
                for (MessageExt msg : msgs) {
                    // It can be seen that each queue is consumed by a unique thread, ensuring order within each queue (partition).
                    System.out.println("consumeThread=" + Thread.currentThread().getName() + ", queueId=" + msg.getQueueId() + ", msgId=" + msg.getMsgId() + ", content:" + new String(msg.getBody()));
                }
                try {
                    // Simulating business logic processing...
                    TimeUnit.SECONDS.sleep(1);
                } catch (Exception e) {
                    e.printStackTrace();
                }
                return ConsumeOrderlyStatus.SUCCESS;
            }
        });
        consumer.start();
        System.out.println("Consumer Started.");
    }
}