RocketMQ的顺序消费和事务消费
一、三种消费 :1.普通消费 2. 顺序消费 3.事务消费
1.1 顺序消费:在网购的时候,我们需要下单,那么下单需要假如有三个顺序,第一、创建订单 ,第二:订单付款,第三:订单完成。也就是这个三个环节要有顺序,这个订单才有意义。RocketMQ可以保证顺序消费,他的实现是生产者(一个生产者可以对多个主题去发送消息)将这个三个消息放在topic(一个topic默认有4个队列)的一个队列里面,单机支持上万个持久化队列,消费端去消费的时候也是只能有一个Consumer去取得这个队列里面的数据,然后顺序消费。
单个节点(Producer端1个、Consumer端1个)
Producer端
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package order;
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import java.util.List;
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import com.alibaba.rocketmq.client.exception.MQBrokerException;
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import com.alibaba.rocketmq.client.exception.MQClientException;
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import com.alibaba.rocketmq.client.producer.DefaultMQProducer;
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import com.alibaba.rocketmq.client.producer.MessageQueueSelector;
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import com.alibaba.rocketmq.client.producer.SendResult;
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import com.alibaba.rocketmq.common.message.Message;
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import com.alibaba.rocketmq.common.message.MessageQueue;
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import com.alibaba.rocketmq.remoting.exception.RemotingException;
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/**
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* Producer,发送顺序消息
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*/
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public class Producer {
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public static void main(String[] args) {
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try {
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DefaultMQProducer producer = new DefaultMQProducer("order_Producer");
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producer.setNamesrvAddr("192.168.100.145:9876;192.168.100.146:9876;192.168.100.149:9876;192.168.100.239:9876");
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producer.start();
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// String[] tags = new String[] { "TagA", "TagB", "TagC", "TagD",
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// "TagE" };
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for (int i = 1; i <= 5; i++) {
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Message msg = new Message("TopicOrderTest", "order_1", "KEY" + i, ("order_1 " + i).getBytes());
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SendResult sendResult = producer.send(msg, new MessageQueueSelector() {
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public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
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Integer id = (Integer) arg;
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int index = id % mqs.size();
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return mqs.get(index);
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}
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}, 0);
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System.out.println(sendResult);
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}
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producer.shutdown();
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} catch (MQClientException e) {
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e.printStackTrace();
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} catch (RemotingException e) {
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e.printStackTrace();
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} catch (MQBrokerException e) {
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e.printStackTrace();
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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}
Consumer端代码
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package order;
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import java.util.List;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.atomic.AtomicLong;
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import com.alibaba.rocketmq.client.consumer.DefaultMQPushConsumer;
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import com.alibaba.rocketmq.client.consumer.listener.ConsumeOrderlyContext;
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import com.alibaba.rocketmq.client.consumer.listener.ConsumeOrderlyStatus;
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import com.alibaba.rocketmq.client.consumer.listener.MessageListenerOrderly;
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import com.alibaba.rocketmq.client.exception.MQClientException;
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import com.alibaba.rocketmq.common.consumer.ConsumeFromWhere;
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import com.alibaba.rocketmq.common.message.MessageExt;
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/**
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* 顺序消息消费,带事务方式(应用可控制Offset什么时候提交)
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*/
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public class Consumer1 {
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public static void main(String[] args) throws MQClientException {
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DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("order_Consumer");
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consumer.setNamesrvAddr("192.168.100.145:9876;192.168.100.146:9876;192.168.100.149:9876;192.168.100.239:9876");
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/**
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* 设置Consumer第一次启动是从队列头部开始消费还是队列尾部开始消费<br>
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* 如果非第一次启动,那么按照上次消费的位置继续消费
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*/
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consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);
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consumer.subscribe("TopicOrderTest", "*");
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consumer.registerMessageListener(new MessageListenerOrderly() {
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AtomicLong consumeTimes = new AtomicLong(0);
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public ConsumeOrderlyStatus consumeMessage(List<MessageExt> msgs, ConsumeOrderlyContext context) {
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// 设置自动提交
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context.setAutoCommit(true);
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for (MessageExt msg : msgs) {
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System.out.println(msg + ",内容:" + new String(msg.getBody()));
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}
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try {
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TimeUnit.SECONDS.sleep(5L);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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;
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return ConsumeOrderlyStatus.SUCCESS;
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}
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});
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consumer.start();
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System.out.println("Consumer1 Started.");
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}
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}
结果如下图所示:
这个五条数据被顺序消费了
多个节点(Producer端1个、Consumer端2个)
Producer端代码:
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package order;
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import java.util.List;
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import com.alibaba.rocketmq.client.exception.MQBrokerException;
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import com.alibaba.rocketmq.client.exception.MQClientException;
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import com.alibaba.rocketmq.client.producer.DefaultMQProducer;
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import com.alibaba.rocketmq.client.producer.MessageQueueSelector;
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import com.alibaba.rocketmq.client.producer.SendResult;
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import com.alibaba.rocketmq.common.message.Message;
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import com.alibaba.rocketmq.common.message.MessageQueue;
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import com.alibaba.rocketmq.remoting.exception.RemotingException;
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/**
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* Producer,发送顺序消息
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*/
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public class Producer {
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public static void main(String[] args) {
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try {
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DefaultMQProducer producer = new DefaultMQProducer("order_Producer");
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producer.setNamesrvAddr("192.168.100.145:9876;192.168.100.146:9876;192.168.100.149:9876;192.168.100.239:9876");
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producer.start();
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// String[] tags = new String[] { "TagA", "TagB", "TagC", "TagD",
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// "TagE" };
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for (int i = 1; i <= 5; i++) {
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Message msg = new Message("TopicOrderTest", "order_1", "KEY" + i, ("order_1 " + i).getBytes());
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SendResult sendResult = producer.send(msg, new MessageQueueSelector() {
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public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
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Integer id = (Integer) arg;
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int index = id % mqs.size();
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return mqs.get(index);
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}
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}, 0);
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System.out.println(sendResult);
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}
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for (int i = 1; i <= 5; i++) {
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Message msg = new Message("TopicOrderTest", "order_2", "KEY" + i, ("order_2 " + i).getBytes());
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SendResult sendResult = producer.send(msg, new MessageQueueSelector() {
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public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
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Integer id = (Integer) arg;
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int index = id % mqs.size();
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return mqs.get(index);
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}
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}, 1);
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System.out.println(sendResult);
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}
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for (int i = 1; i <= 5; i++) {
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Message msg = new Message("TopicOrderTest", "order_3", "KEY" + i, ("order_3 " + i).getBytes());
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SendResult sendResult = producer.send(msg, new MessageQueueSelector() {
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public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
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Integer id = (Integer) arg;
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int index = id % mqs.size();
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return mqs.get(index);
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}
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}, 2);
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System.out.println(sendResult);
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}
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producer.shutdown();
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} catch (MQClientException e) {
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e.printStackTrace();
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} catch (RemotingException e) {
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e.printStackTrace();
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} catch (MQBrokerException e) {
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e.printStackTrace();
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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}
Consumer1
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/**
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* 顺序消息消费,带事务方式(应用可控制Offset什么时候提交)
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*/
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public class Consumer1 {
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public static void main(String[] args) throws MQClientException {
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DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("order_Consumer");
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consumer.setNamesrvAddr("192.168.100.145:9876;192.168.100.146:9876;192.168.100.149:9876;192.168.100.239:9876");
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/**
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* 设置Consumer第一次启动是从队列头部开始消费还是队列尾部开始消费<br>
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* 如果非第一次启动,那么按照上次消费的位置继续消费
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*/
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consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);
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consumer.subscribe("TopicOrderTest", "*");
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/**
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* 实现了MessageListenerOrderly表示一个队列只会被一个线程取到
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*,第二个线程无法访问这个队列
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*/
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consumer.registerMessageListener(new MessageListenerOrderly() {
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AtomicLong consumeTimes = new AtomicLong(0);
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public ConsumeOrderlyStatus consumeMessage(List<MessageExt> msgs, ConsumeOrderlyContext context) {
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// 设置自动提交
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context.setAutoCommit(true);
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for (MessageExt msg : msgs) {
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System.out.println(msg + ",内容:" + new String(msg.getBody()));
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}
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try {
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TimeUnit.SECONDS.sleep(5L);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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;
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return ConsumeOrderlyStatus.SUCCESS;
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}
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});
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consumer.start();
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System.out.println("Consumer1 Started.");
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}
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}
Consumer2
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/**
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* 顺序消息消费,带事务方式(应用可控制Offset什么时候提交)
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*/
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public class Consumer2 {
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public static void main(String[] args) throws MQClientException {
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DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("order_Consumer");
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consumer.setNamesrvAddr("192.168.100.145:9876;192.168.100.146:9876;192.168.100.149:9876;192.168.100.239:9876");
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/**
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* 设置Consumer第一次启动是从队列头部开始消费还是队列尾部开始消费<br>
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* 如果非第一次启动,那么按照上次消费的位置继续消费
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*/
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consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);
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consumer.subscribe("TopicOrderTest", "*");
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/**
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* 实现了MessageListenerOrderly表示一个队列只会被一个线程取到
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*,第二个线程无法访问这个队列
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*/
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consumer.registerMessageListener(new MessageListenerOrderly() {
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AtomicLong consumeTimes = new AtomicLong(0);
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public ConsumeOrderlyStatus consumeMessage(List<MessageExt> msgs, ConsumeOrderlyContext context) {
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// 设置自动提交
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context.setAutoCommit(true);
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for (MessageExt msg : msgs) {
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System.out.println(msg + ",内容:" + new String(msg.getBody()));
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}
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try {
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TimeUnit.SECONDS.sleep(5L);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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;
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return ConsumeOrderlyStatus.SUCCESS;
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}
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});
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consumer.start();
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System.out.println("Consumer2 Started.");
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}
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}
先启动Consumer1和Consumer2,然后启动Producer,Producer会发送15条消息
Consumer1消费情况如图,都按照顺序执行了
Consumer2消费情况如图,都按照顺序执行了
二、事务消费
这里说的主要是分布式事物。下面的例子的数据库分别安装在不同的节点上。
事物消费需要先说说什么是事物。比如说:我们跨行转账,从工商银行转到建设银行,也就是我从工商银行扣除1000元之后,我的建设银行也必须加1000元。这样才能保证数据的一致性。假如工商银行转1000元之后,建设银行的服务器突然宕机,那么我扣除了1000,但是并没有在建设银行给我加1000,就出现了数据的不一致。因此加1000和减1000才行,减1000和减1000必须一起成功,一起失败。
再比如,我们进行网购的时候,我们下单之后,订单提交成功,仓库商品的数量必须减一。但是订单可能是一个数据库,仓库数量可能又是在另个数据库里面。有可能订单提交成功之后,仓库数量服务器突然宕机。这样也出现了数据不一致的问题。
使用消息队列来解决分布式事物:
现在我们去外面饭店吃饭,很多时候都不会直接给了钱之后直接在付款的窗口递饭菜,而是付款之后他会给你一张小票,你拿着这个小票去出饭的窗口取饭。这里和我们的系统类似,提高了吞吐量。即使你到第二个窗口,师傅告诉你已经没饭了,你可以拿着这个凭证去退款,即使中途由于出了意外你无法到达窗口进行取饭,但是只要凭证还在,可以将钱退给你。这样就保证了数据的一致性。
如何保证凭证(消息)有2种方法:
1、在工商银行扣款的时候,余额表扣除1000,同时记录日志,而且这2个表是在同一个数据库实例中,可以使用本地事物解决。然后我们通知建设银行需要加1000给该用户,建设银行收到之后给我返回已经加了1000给用户的确认信息之后,我再标记日志表里面的日志为已经完成。
2、通过消息中间件
原文地址:http://www.jianshu.com/p/453c6e7ff81c
RocketMQ第一阶段发送Prepared消息时,会拿到消息的地址,第二阶段执行本地事物,第三阶段通过第一阶段拿到的地址去访问消息,并修改消息的状态。
细心的你可能又发现问题了,如果确认消息发送失败了怎么办?RocketMQ会定期扫描消息集群中的事物消息,如果发现了Prepared消息,它会向消息发送端(生产者)确认,Bob的钱到底是减了还是没减呢?如果减了是回滚还是继续发送确认消息呢?RocketMQ会根据发送端设置的策略来决定是回滚还是继续发送确认消息。这样就保证了消息发送与本地事务同时成功或同时失败。
例子:
Consumer 端
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package transaction;
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import java.util.List;
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import com.alibaba.rocketmq.client.consumer.DefaultMQPushConsumer;
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import com.alibaba.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext;
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import com.alibaba.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus;
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import com.alibaba.rocketmq.client.consumer.listener.MessageListenerConcurrently;
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import com.alibaba.rocketmq.client.exception.MQClientException;
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import com.alibaba.rocketmq.common.consumer.ConsumeFromWhere;
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import com.alibaba.rocketmq.common.message.MessageExt;
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/**
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* Consumer,订阅消息
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*/
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public class Consumer {
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public static void main(String[] args) throws InterruptedException, MQClientException {
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DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("transaction_Consumer");
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consumer.setNamesrvAddr("192.168.100.145:9876;192.168.100.146:9876;192.168.100.149:9876;192.168.100.239:9876");
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consumer.setConsumeMessageBatchMaxSize(10);
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/**
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* 设置Consumer第一次启动是从队列头部开始消费还是队列尾部开始消费<br>
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* 如果非第一次启动,那么按照上次消费的位置继续消费
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*/
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consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);
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consumer.subscribe("TopicTransactionTest", "*");
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consumer.registerMessageListener(new MessageListenerConcurrently() {
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public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeConcurrentlyContext context) {
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try {
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for (MessageExt msg : msgs) {
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System.out.println(msg + ",内容:" + new String(msg.getBody()));
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}
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} catch (Exception e) {
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e.printStackTrace();
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return ConsumeConcurrentlyStatus.RECONSUME_LATER;// 重试
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}
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return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;// 成功
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}
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});
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consumer.start();
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System.out.println("transaction_Consumer Started.");
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}
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}
Producer端
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package transaction;
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import com.alibaba.rocketmq.client.exception.MQClientException;
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import com.alibaba.rocketmq.client.producer.SendResult;
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import com.alibaba.rocketmq.client.producer.TransactionCheckListener;
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import com.alibaba.rocketmq.client.producer.TransactionMQProducer;
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import com.alibaba.rocketmq.common.message.Message;
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/**
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* 发送事务消息例子
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*
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*/
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public class Producer {
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public static void main(String[] args) throws MQClientException, InterruptedException {
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TransactionCheckListener transactionCheckListener = new TransactionCheckListenerImpl();
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TransactionMQProducer producer = new TransactionMQProducer("transaction_Producer");
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producer.setNamesrvAddr("192.168.100.145:9876;192.168.100.146:9876;192.168.100.149:9876;192.168.100.239:9876");
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// 事务回查最小并发数
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producer.setCheckThreadPoolMinSize(2);
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// 事务回查最大并发数
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producer.setCheckThreadPoolMaxSize(2);
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// 队列数
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producer.setCheckRequestHoldMax(2000);
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producer.setTransactionCheckListener(transactionCheckListener);
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producer.start();
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// String[] tags = new String[] { "TagA", "TagB", "TagC", "TagD", "TagE"
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// };
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TransactionExecuterImpl tranExecuter = new TransactionExecuterImpl();
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for (int i = 1; i <= 2; i++) {
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try {
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Message msg = new Message("TopicTransactionTest", "transaction" + i, "KEY" + i,
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("Hello RocketMQ " + i).getBytes());
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SendResult sendResult = producer.sendMessageInTransaction(msg, tranExecuter, null);
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System.out.println(sendResult);
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Thread.sleep(10);
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} catch (MQClientException e) {
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e.printStackTrace();
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}
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}
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for (int i = 0; i < 100000; i++) {
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Thread.sleep(1000);
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}
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producer.shutdown();
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}
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}
TransactionExecuterImpl --执行本地事务
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package transaction;
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import com.alibaba.rocketmq.client.producer.LocalTransactionExecuter;
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import com.alibaba.rocketmq.client.producer.LocalTransactionState;
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import com.alibaba.rocketmq.common.message.Message;
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/**
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* 执行本地事务
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*/
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public class TransactionExecuterImpl implements LocalTransactionExecuter {
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// private AtomicInteger transactionIndex = new AtomicInteger(1);
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public LocalTransactionState executeLocalTransactionBranch(final Message msg, final Object arg) {
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System.out.println("执行本地事务msg = " + new String(msg.getBody()));
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System.out.println("执行本地事务arg = " + arg);
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String tags = msg.getTags();
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if (tags.equals("transaction2")) {
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System.out.println("======我的操作============,失败了 -进行ROLLBACK");
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return LocalTransactionState.ROLLBACK_MESSAGE;
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}
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return LocalTransactionState.COMMIT_MESSAGE;
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// return LocalTransactionState.UNKNOW;
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}
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}
TransactionCheckListenerImpl--未决事务,服务器回查客户端(目前已经被阉割啦)
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package transaction;
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import com.alibaba.rocketmq.client.producer.LocalTransactionState;
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import com.alibaba.rocketmq.client.producer.TransactionCheckListener;
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import com.alibaba.rocketmq.common.message.MessageExt;
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/**
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* 未决事务,服务器回查客户端
-
*/
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public class TransactionCheckListenerImpl implements TransactionCheckListener {
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// private AtomicInteger transactionIndex = new AtomicInteger(0);
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//在这里,我们可以根据由MQ回传的key去数据库查询,这条数据到底是成功了还是失败了。
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public LocalTransactionState checkLocalTransactionState(MessageExt msg) {
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System.out.println("未决事务,服务器回查客户端msg =" + new String(msg.getBody().toString()));
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// return LocalTransactionState.ROLLBACK_MESSAGE;
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return LocalTransactionState.COMMIT_MESSAGE;
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// return LocalTransactionState.UNKNOW;
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}
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}
producer端:发送数据到MQ,并且处理本地事物。这里模拟了一个成功一个失败。Consumer只会接收到本地事物成功的数据。第二个数据失败了,不会被消费。
Consumer只会接收到一个,第二个数据不会被接收到
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