5 分布式事务怎么做的

/**
 * 事务消息
 */
@Service
public class OrderService {

    @Autowired
    private RocketMQTemplate rocketMQTemplate;

    public void createOrder(String orderId) {
        Message<String> msg = MessageBuilder
                .withPayload(orderId)
                .build();
        // 发送事务消息
        rocketMQTemplate.sendMessageInTransaction(
                "order_tx_group",
                "orderTopic",
                msg,
                orderId
        );
    }
}

/**
 * 事务监听器
 */
@RocketMQTransactionListener(txProducerGroup = "order_tx_group")
public class OrderTxListener implements RocketMQLocalTransactionListener {

    @Autowired
    private OrderRepository orderRepository;

    /**
     * 执行本地事务
     */
    @Override
    public RocketMQLocalTransactionState executeLocalTransaction(
            Message msg, Object arg) {

        String orderId = (String) arg;
        try {

            // 本地事务
            Order order = new Order(orderId);
            orderRepository.save(order);
            return RocketMQLocalTransactionState.COMMIT;
        } catch (Exception e) {
            return RocketMQLocalTransactionState.ROLLBACK;
        }
    }

    /**
     * Broker回查本地事务
     */
    @Override
    public RocketMQLocalTransactionState checkLocalTransaction(Message msg) {
        String orderId = new String((byte[]) msg.getPayload());
        boolean exists = orderRepository.existsById(orderId);
        if (exists) {
            return RocketMQLocalTransactionState.COMMIT;
        }
        return RocketMQLocalTransactionState.ROLLBACK;
    }
}

/**
 * 消费端
 */
@Service
@RocketMQMessageListener(
        topic = "orderTopic",
        consumerGroup = "order_consumer_group"
)
public class OrderConsumer implements RocketMQListener<String> {

    @Override
    public void onMessage(String orderId) {
        System.out.println("收到订单消息：" + orderId);

        // 扣库存
        // 更新缓存
        // 通知其他系统
    }
}