RocketMQ：事务消息

淡淡的烟草味﹌ 2023-06-26 11:00 19阅读 0赞

流程

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使用限制

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<dependency>
         <groupId>org.apache.rocketmq</groupId>
         <artifactId>rocketmq-client</artifactId>
         <version>4.4.0</version>
    </dependency>

生产者

public class Producer {
    
        public static void main(String[] args) throws Exception {
            // 1.创建消息生产者producer，并制定生产者组名  事务生产者
            TransactionMQProducer producer = new TransactionMQProducer("group5");
            // 2.指定NameServer地址
            producer.setNamesrvAddr("localhost:9876");
            // 生产者监听器
            producer.setTransactionListener(new TransactionListener() {
                /**
                 * 在该方法中执行本地事务 第二步
                 * @param message
                 * @param o
                 * @return
                 */
                public LocalTransactionState executeLocalTransaction(Message message, Object o) {
                    if (StringUtils.equals("taga",message.getTags())){
                        return LocalTransactionState.COMMIT_MESSAGE;
                    } else if (StringUtils.equals("tagb",message.getTags())){
                        return LocalTransactionState.ROLLBACK_MESSAGE;
                    } else if (StringUtils.equals("tagc",message.getTags())){
                        return LocalTransactionState.UNKNOW;
                    }
                    return LocalTransactionState.UNKNOW;
                }
    
                /**
                 * 该方法是mq进行消息事务状态回查 第三步
                 * @param messageExt
                 * @return
                 */
                public LocalTransactionState checkLocalTransaction(MessageExt messageExt) {
                    System.out.println("消息的tag："+messageExt.getTags());
                    return LocalTransactionState.COMMIT_MESSAGE;
                }
            });
            // 3.启动producer
            producer.start();
            String[] tags = {"taga","tagb","tagc"};
            for (int i = 0; i < 3; i++) {
                // 4.创建消息对象，指定主题Topic、Tag和消息体
                /*
                参数1：消息主题Topic
                参数2：消息Tagf
                参数3：消息内容
                 */
                Message msg = new Message("transactionTopic",tags[i],("hello world"+i).getBytes());
                // 5.发送消息结果包含  发送状态  消息id 消息接收队列id等 第一步
                SendResult result = producer.sendMessageInTransaction(msg,null);
                System.out.println("发送结果"+result);
    
                // 线程睡眠1秒
                TimeUnit.SECONDS.sleep(3);
            }
            // 6关闭生产者producer
    //        producer.shutdown();
        }
    }

消费者

public class Consumer {
    
        public static void main(String[] args) throws MQClientException {
            // 1.创建消费者Consumer，制定消费者组名
            DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("group5");
            // 2.指定Nameserver地址
            consumer.setNamesrvAddr("localhost:9876");
            // 3.订阅主题Topic和Tag
            consumer.subscribe("transactionTopic","*");
    
            // 4.设置回调函数，处理消息
            consumer.registerMessageListener(new MessageListenerConcurrently() {
                //接收消息内容
                public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> list, ConsumeConcurrentlyContext consumeConcurrentlyContext) {
                    for (MessageExt messageExt : list) {
                        System.out.println(new String(messageExt.getBody()));
                    }
                    return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
                }
            });
            // 5.启动消费者consumer
            consumer.start();
            System.out.println("消费者启动");
        }
    
    }

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