使用微服务架构开发Java功能的核心原则与技巧

// UserService.java
public class UserService {
    public void createUser(User user) {
        // 省略创建用户的逻辑
    }

    public User getUserById(String userId) {
        // 省略获取用户信息的逻辑
        return user;
    }
}

// OrderService.java
public class OrderService {
    public void createOrder(Order order) {
        // 省略创建订单的逻辑
    }

    public Order getOrderById(String orderId) {
        // 省略获取订单信息的逻辑
        return order;
    }
}

@FeignClient("user-service")
public interface UserService {
    @PostMapping("/users")
    User createUser(@RequestBody User user);

    @GetMapping("/users/{userId}")
    User getUserById(@PathVariable("userId") String userId);
}

@FeignClient("order-service")
public interface OrderService {
    @PostMapping("/orders")
    Order createOrder(@RequestBody Order order);

    @GetMapping("/orders/{orderId}")
    Order getOrderById(@PathVariable("orderId") String orderId);
}

// UserCreatedEvent.java
public class UserCreatedEvent {
    private String userId;
    // 省略其他属性及getter和setter方法
}

// OrderCreatedListener.java
@Component
public class OrderCreatedListener {
    @Autowired
    private UserService userService;

    @KafkaListener(topics = "order-created")
    public void onOrderCreated(OrderCreatedEvent event) {
        User user = userService.getUserById(event.getUserId());
        // 处理订单创建事件
    }
}

@FeignClient(name = "user-service", fallback = UserServiceFallback.class)
public interface UserService {
    // 省略方法定义
}

@Component
public class UserServiceFallback implements UserService {
    @Override
    public User createUser(User user) {
        // 提供备选方案，例如返回默认用户对象
    }

    @Override
    public User getUserById(String userId) {
        // 提供备选方案，例如返回缓存中的用户对象
    }
}