microwind/ai-skills/application-service

@Service
@Transactional
public class OrderApplicationService {
    private final OrderRepository orderRepo;
    private final CustomerRepository customerRepo;
    private final EventPublisher eventPublisher;
 
    // 用例：下单
    public OrderDTO placeOrder(PlaceOrderCommand cmd) {
        // 1. 加载领域对象
        Customer customer = customerRepo.findById(cmd.getCustomerId())
            .orElseThrow(() -> new NotFoundException("客户不存在"));
        Order order = orderRepo.findById(cmd.getOrderId())
            .orElseThrow(() -> new NotFoundException("订单不存在"));
 
        // 2. 调用领域逻辑（逻辑在 Order 中）
        order.place();
 
        // 3. 持久化
        orderRepo.save(order);
 
        // 4. 发布事件
        order.getDomainEvents().forEach(eventPublisher::publish);
        order.clearDomainEvents();
 
        // 5. 返回 DTO
        return OrderDTO.from(order);
    }
 
    // 用例：取消订单
    public void cancelOrder(CancelOrderCommand cmd) {
        Order order = orderRepo.findById(cmd.getOrderId())
            .orElseThrow(() -> new NotFoundException("订单不存在"));
 
        order.cancel(cmd.getReason());  // 业务逻辑在领域对象中
 
        orderRepo.save(order);
        order.getDomainEvents().forEach(eventPublisher::publish);
        order.clearDomainEvents();
    }
}

class OrderApplicationService:
    def __init__(self, order_repo, customer_repo, event_publisher):
        self.order_repo = order_repo
        self.customer_repo = customer_repo
        self.event_publisher = event_publisher
    def place_order(self, cmd: PlaceOrderCommand) -> OrderDTO:
        customer = self.customer_repo.find_by_id(cmd.customer_id)
        if not customer:
            raise NotFoundError("客户不存在")
        order = self.order_repo.find_by_id(cmd.order_id)
        order.place()  # 业务逻辑在领域对象中
        self.order_repo.save(order)
        for event in order.collect_events():
            self.event_publisher.publish(event)
        return OrderDTO.from_domain(order)

❌ 应用服务中写业务逻辑
public OrderDTO placeOrder(PlaceOrderCommand cmd) {
    Order order = orderRepo.findById(cmd.getOrderId());
    // 业务逻辑泄漏到应用层！
    if (order.getItems().isEmpty()) throw new Exception("订单为空");
    if (order.getStatus() != DRAFT) throw new Exception("状态错误");
    order.setStatus(PLACED);
    order.setTotalAmount(calculateTotal(order));
}
 
✅ 应用服务只做编排
public OrderDTO placeOrder(PlaceOrderCommand cmd) {
    Order order = orderRepo.findById(cmd.getOrderId());
    order.place();  // 所有业务逻辑在 Order 内部
    orderRepo.save(order);
}