✨ feat: 주문 생성 API 개발

src/main/java/com/example/Centralthon/domain/order/entity/Order.java

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+package com.example.Centralthon.domain.order.entity;
+
+import com.example.Centralthon.global.entity.BaseEntity;
+import jakarta.persistence.*;
+import lombok.*;
+
+@Getter
+@Setter
+@Builder
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@AllArgsConstructor(access = AccessLevel.PROTECTED)
+@Entity
+@Table(name = "orders")
+public class Order extends BaseEntity {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name="order_id")
+    private Long id;
+
+    @Column(name = "pick_up_code", nullable = false, unique = true, length = 6)
+    private String pickUpCode;
+
+    @Column(nullable = false)
+    private int price;
+
+    @Column(name = "is_picked_up", nullable = false)
+    private boolean pickedUp;
+
+    public static Order toEntity(String pickUpCode, int price){
+        return Order.builder()
+                .pickUpCode(pickUpCode)
+                .price(price)
+                .pickedUp(false)
+                .build();
+    }
+}

src/main/java/com/example/Centralthon/domain/order/entity/OrderItem.java

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+package com.example.Centralthon.domain.order.entity;
+
+import com.example.Centralthon.domain.menu.entity.Menu;
+import com.example.Centralthon.domain.store.entity.Store;
+import com.example.Centralthon.global.entity.BaseEntity;
+import jakarta.persistence.*;
+import lombok.*;
+
+@Getter
+@Setter
+@Builder
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@AllArgsConstructor(access = AccessLevel.PROTECTED)
+@Entity
+@Table(name = "order_items")
+public class OrderItem extends BaseEntity {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name="order_items_id")
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "order_id", nullable = false)
+    private Order order;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "menu_id", nullable = false)
+    private Menu menu;
+
+    @Column(nullable = false)
+    private int quantity;
+
+    public static OrderItem toEntity(Order order, Menu menu, int quantity) {
+        return OrderItem.builder()
+                .order(order)
+                .menu(menu)
+                .quantity(quantity)
+                .build();
+    }
+}

src/main/java/com/example/Centralthon/domain/order/exception/CodeNotCreatedException.java

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+package com.example.Centralthon.domain.order.exception;
+
+import com.example.Centralthon.global.exception.BaseException;
+
+public class CodeNotCreatedException extends BaseException {
+    public CodeNotCreatedException() {
+        super(OrderErrorCode.CODE_NOT_CREATED);
+    }
+}

src/main/java/com/example/Centralthon/domain/order/exception/OrderErrorCode.java

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+package com.example.Centralthon.domain.order.exception;
+
+import com.example.Centralthon.global.response.code.BaseResponseCode;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+@Getter
+@AllArgsConstructor
+public enum OrderErrorCode implements BaseResponseCode {
+    CODE_NOT_CREATED("ORDER_500_1",500,"서버에서 유일한 픽업 코드를 생성하지 못했습니다.");
+
+    private final String code;
+    private final int httpStatus;
+    private final String message;
+}

src/main/java/com/example/Centralthon/domain/order/repository/OrderItemRepository.java

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+package com.example.Centralthon.domain.order.repository;
+
+import com.example.Centralthon.domain.order.entity.OrderItem;
+import org.springframework.data.repository.CrudRepository;
+
+public interface OrderItemRepository extends CrudRepository<OrderItem, Long> {
+}

src/main/java/com/example/Centralthon/domain/order/repository/OrderRepository.java

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+package com.example.Centralthon.domain.order.repository;
+
+import com.example.Centralthon.domain.order.entity.Order;
+import org.springframework.data.repository.CrudRepository;
+
+import java.util.Optional;
+
+public interface OrderRepository extends CrudRepository<Order, Long> {
+    Optional<Order> findByPickUpCode(String pickUpCode);
+}

src/main/java/com/example/Centralthon/domain/order/service/OrderService.java

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+package com.example.Centralthon.domain.order.service;
+
+import com.example.Centralthon.domain.order.web.dto.OrderReq;
+import com.example.Centralthon.domain.order.web.dto.OrderRes;
+
+import java.util.List;
+
+public interface OrderService {
+    OrderRes orderMenus(OrderReq orderReq);
+}

src/main/java/com/example/Centralthon/domain/order/service/OrderServiceImpl.java

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+package com.example.Centralthon.domain.order.service;
+
+import com.example.Centralthon.domain.menu.entity.Menu;
+import com.example.Centralthon.domain.menu.exception.MenuNotFoundException;
+import com.example.Centralthon.domain.menu.repository.MenuRepository;
+import com.example.Centralthon.domain.order.entity.Order;
+import com.example.Centralthon.domain.order.entity.OrderItem;
+import com.example.Centralthon.domain.order.exception.CodeNotCreatedException;
+import com.example.Centralthon.domain.order.repository.OrderItemRepository;
+import com.example.Centralthon.domain.order.repository.OrderRepository;
+import com.example.Centralthon.domain.order.web.dto.OrderItemListReq;
+import com.example.Centralthon.domain.order.web.dto.OrderReq;
+import com.example.Centralthon.domain.order.web.dto.OrderRes;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Lazy;
+import org.springframework.dao.DataIntegrityViolationException;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Propagation;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ThreadLocalRandom;
+
+@Service
+@RequiredArgsConstructor
+public class OrderServiceImpl implements OrderService {
+    @Lazy @Autowired
+    private OrderServiceImpl selfProxy;
+
+    private final MenuRepository menuRepository;
+    private final OrderRepository orderRepository;
+    private final OrderItemRepository orderItemRepository;
+
+    @Override
+    @Transactional
+    public OrderRes orderMenus(OrderReq orderReq) {
+        Map<Long, Integer> orderList = new HashMap<>();
+
+        for (OrderItemListReq orderItemListReq : orderReq.getItems()) {
+            orderList.merge(orderItemListReq.getMenuId(), orderItemListReq.getCount(), Integer::sum);
+        }
+
+        // 메뉴 id가 없을 경우 -> MenuNotFoundException
+        List<Menu> menuList = menuRepository.findAllById(orderList.keySet());
+        if(menuList.size() != orderList.keySet().size()) {
+            throw new MenuNotFoundException();
+        }
+
+        // 최종 결제 금액 계산
+        int totalPrice = 0;
+        for (Menu menu : menuList) {
+            // 오버플로우 방지를 위한 addExact, multiplyExact 사용
+            totalPrice = Math.addExact(totalPrice, Math.multiplyExact(menu.getSalePrice(), orderList.get(menu.getId())));
+        }
+
+        Order order = createOrderWithUniqueCode(totalPrice);
+
+        List<OrderItem> orderItemList = new ArrayList<>();
+        for(Menu menu : menuList) {
+            OrderItem orderItem = OrderItem.toEntity(order, menu, orderList.get(menu.getId()));
+            orderItemList.add(orderItem);
+        }
+        orderItemRepository.saveAll(orderItemList);
+
+        return OrderRes.from(order);
+    }
+
+    private Order createOrderWithUniqueCode(int totalPrice) {
+        for(int i = 0; i < 10; i++) {
+            String code = generatePickUpCode();
+            try{
+                // 프록시를 적용해주지 않으면, this.saveOrder가 실행되어 트랙잭션이 실행되지 않음
+                return selfProxy.saveOrder(code, totalPrice);
+            } catch (DataIntegrityViolationException e) {
+                // 다음 실행 진행
+            }
+        }
+        throw new CodeNotCreatedException();
+    }
+
+    /**
+     * 같은 트랙잭션에서 실패하면 rollback-only 상태로 인해 정상 커밋이 불가능하므로,
+     * 새 트랜잭션을 열어 새로운 픽업 코드를 저장하도록 시도
+     * -> 새 트랜잭션을 열기 위해 @Transactional(propagation = Propagation.REQUIRES_NEW) 사용
+     * -> @Transactional(propagation = Propagation.REQUIRES_NEW)는 기존 트랜잭션을 중지시키고, 새 트랜잭션 시작
+     */
+    @Transactional(propagation = Propagation.REQUIRES_NEW)
+    public Order saveOrder(String code, int totalPrice){
+        Order order = Order.toEntity(code, totalPrice);
+        return orderRepository.save(order);
+    }
+
+    /**
+     * 픽업 코드(영문 두자리 + 숫자 네자리) 생성 메서드
+     */
+    private String generatePickUpCode() {
+        ThreadLocalRandom random = ThreadLocalRandom.current();
+        char[] codeArray = new char[6];
+        String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+        String number = "0123456789";
+
+        for (int i = 0; i < 2; i++) {
+            char alpha = alphabet.charAt(random.nextInt(alphabet.length()));
+            codeArray[i] = alpha;
+        }
+
+        for (int i = 0; i < 4; i++) {
+            char num = number.charAt(random.nextInt(number.length()));
+            codeArray[i + 2] = num;
+        }
+
+        return new String(codeArray);
+    }
+}

src/main/java/com/example/Centralthon/domain/order/web/controller/OrderController.java

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+package com.example.Centralthon.domain.order.web.controller;
+
+import com.example.Centralthon.domain.order.service.OrderService;
+import com.example.Centralthon.domain.order.web.dto.OrderReq;
+import com.example.Centralthon.domain.order.web.dto.OrderRes;
+import com.example.Centralthon.global.response.SuccessResponse;
+import com.example.Centralthon.global.response.code.SuccessResponseCode;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/api/orders")
+public class OrderController {
+    private final OrderService orderService;
+
+    @PostMapping
+    public ResponseEntity<SuccessResponse<OrderRes>> createOrder(@RequestBody @Valid OrderReq orderReq) {
+        OrderRes orderRes = orderService.orderMenus(orderReq);
+        return ResponseEntity.status(HttpStatus.CREATED).body(SuccessResponse.of(orderRes, SuccessResponseCode.SUCCESS_CREATED));
+    }
+}

src/main/java/com/example/Centralthon/domain/order/web/dto/OrderItemListReq.java

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+package com.example.Centralthon.domain.order.web.dto;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotNull;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+public class OrderItemListReq {
+    @NotNull(message = "메뉴 기본 키는 필수 값입니다.")
+    private Long menuId;
+
+    @NotNull(message = "수량은 필수 값입니다.")
+    @Min(value = 1, message = "수량은 1 이상이어야 합니다.")
+    private Integer count;
+}

src/main/java/com/example/Centralthon/domain/order/web/dto/OrderReq.java

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+package com.example.Centralthon.domain.order.web.dto;
+
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.NotEmpty;
+import lombok.Getter;
+import lombok.Setter;
+
+import java.util.List;
+
+@Getter
+@Setter
+public class OrderReq {
+    @NotEmpty(message = "주문 항목은 빈 배열일 수 없습니다.")
+    List<@Valid OrderItemListReq> items;
+}

src/main/java/com/example/Centralthon/domain/order/web/dto/OrderRes.java

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+package com.example.Centralthon.domain.order.web.dto;
+
+import com.example.Centralthon.domain.order.entity.Order;
+
+public record OrderRes(
+        String code
+) {
+    public static OrderRes from(Order order) {
+        return new OrderRes(order.getPickUpCode());
+    }
+}