顺序消息的概念
消息有序指的是可以按照消息的发送顺序来消费(FIFO)。
RocketMQ可以严格的保证消息有序，可以分为分区有序或者全局有序。
顺序消费的原理
在默认的情况下消息发送会采取Round Robin轮询方式把消息发送到不同的queue(分区队列)；
而消费消息的时候从多个queue上拉取消息，这种情况发送和消费是不能保证顺序。
但是如果控制发送的顺序消息只依次发送到同一个queue中，消费的时候只从这个queue上依次拉取，则就保证了顺序。
当发送和消费参与的queue只有一个，则是全局有序；如果多个queue参与，则为分区有序，即相对每个queue，消息都是有序的。
消费状态
package org.apache.rocketmq.client.consumer.listener; public enum ConsumeOrderlyStatus { /** * Success consumption */ SUCCESS, /** * Suspend current queue a moment * 不能跳过消息，等待一下 */ SUSPEND_CURRENT_QUEUE_A_MOMENT; }
演示
下面用订单进行分区有序的示例。一个订单的顺序流程是：创建、付款、推送、完成。订单号相同的消息会被先后发送到同一个队列中，消费时，同一个OrderId获取到的肯定是同一个队列。
Producer
package com.artisan.rocketmq.order; import org.apache.rocketmq.client.producer.DefaultMQProducer; import org.apache.rocketmq.client.producer.MessageQueueSelector; import org.apache.rocketmq.client.producer.SendResult; import org.apache.rocketmq.common.message.Message; import org.apache.rocketmq.common.message.MessageQueue; import org.apache.rocketmq.remoting.common.RemotingHelper; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; import java.util.List; /** * @author 小工匠 * @version v1.0 * @create 2019-11-10 16:38 * @motto show me the code ,change the word * @blog https://artisan.blog.csdn.net/ * @description **/ public class OrderedProducer { public static void main(String[] args) throws Exception { DefaultMQProducer producer = new DefaultMQProducer("ordered_group_name"); producer.setNamesrvAddr("192.168.18.130:9876;192.168.18.131:9876"); producer.start(); String[] tags = new String[]{"TagA", "TagC", "TagD"}; // 订单列表 List<OrderStep> orderList = buildOrders(); Date date = new Date(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String dateStr = sdf.format(date); for (int i = 0; i < 10; i++) { // 加个时间前缀 String body = dateStr + " Hello RocketMQ "+ i + " " + orderList.get(i); Message msg = new Message("TopicTest", tags[i % tags.length], "KEY" + i, body.getBytes(RemotingHelper.DEFAULT_CHARSET)); SendResult sendResult = producer.send(msg, new MessageQueueSelector() { @Override public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) { Long id = (Long) arg; //根据订单id选择发送queue long index = id % mqs.size(); return mqs.get((int) index); } }, orderList.get(i).getOrderId());//订单id System.out.println(String.format("SendResult status:%s, queueId:%d, body:%s", sendResult.getSendStatus(), sendResult.getMessageQueue().getQueueId(), body)); } producer.shutdown(); } /** * 生成模拟订单数据 */ private static List<OrderStep> buildOrders() { List<OrderStep> orderList = new ArrayList<OrderStep>(); OrderStep orderDemo = new OrderStep(); orderDemo.setOrderId(15103111039L); orderDemo.setDesc("创建"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103111065L); orderDemo.setDesc("创建"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103111039L); orderDemo.setDesc("付款"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103117235L); orderDemo.setDesc("创建"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103111065L); orderDemo.setDesc("付款"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103117235L); orderDemo.setDesc("付款"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103111065L); orderDemo.setDesc("完成"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103111039L); orderDemo.setDesc("推送"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103117235L); orderDemo.setDesc("完成"); orderList.add(orderDemo); orderDemo = new OrderStep(); orderDemo.setOrderId(15103111039L); orderDemo.setDesc("购物车"); orderList.add(orderDemo); return orderList; } /** * 订单的步骤 */ private static class OrderStep { private long orderId; private String desc; public long getOrderId() { return orderId; } public void setOrderId(long orderId) { this.orderId = orderId; } public String getDesc() { return desc; } public void setDesc(String desc) { this.desc = desc; } @Override public String toString() { return "OrderStep{" + "orderId=" + orderId + ", desc='" + desc + '\'' + '}'; } } }
日志
Consumer
package com.artisan.rocketmq.order; import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer; import org.apache.rocketmq.client.consumer.listener.ConsumeOrderlyContext; import org.apache.rocketmq.client.consumer.listener.ConsumeOrderlyStatus; import org.apache.rocketmq.client.consumer.listener.MessageListenerOrderly; import org.apache.rocketmq.common.consumer.ConsumeFromWhere; import org.apache.rocketmq.common.message.MessageExt; import org.apache.rocketmq.remoting.common.RemotingHelper; import java.io.UnsupportedEncodingException; import java.util.List; import java.util.Random; import java.util.concurrent.TimeUnit; /** * @author 小工匠 * @version v1.0 * @create 2019-11-10 16:38 * @motto show me the code ,change the word * @blog https://artisan.blog.csdn.net/ * @description **/ public class OrderedConsumer { public static void main(String[] args) throws Exception { DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("ordered_group_name"); consumer.setNamesrvAddr("192.168.18.130:9876;192.168.18.131:9876"); /** * 设置消费位置 */ consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET); consumer.subscribe("TopicTest", "*"); // 有序消费 MessageListenerOrderly consumer.registerMessageListener(new MessageListenerOrderly() { @Override public ConsumeOrderlyStatus consumeMessage(List<MessageExt> msgs, ConsumeOrderlyContext context) { context.setAutoCommit(true); Random random = new Random(); for (MessageExt msg : msgs) { // 可以看到每个queue有唯一的consume来消费, 订单对每个queue(分区)有序 try { System.out.println("consumeThread=" + Thread.currentThread().getName() + ", queueId=" + msg.getQueueId() + ", content:" + new String(msg.getBody(), RemotingHelper.DEFAULT_CHARSET)); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } try { //模拟业务逻辑处理中... TimeUnit.SECONDS.sleep(random.nextInt(10)); } catch (Exception e) { e.printStackTrace(); } return ConsumeOrderlyStatus.SUCCESS; } }); consumer.start(); System.out.printf("Consumer Started.%n"); } }
运行日志
