交易下单1（未完成）

README.md

@@ -18,7 +18,7 @@
 | ----------------- | --------------------- | --------------------------------------- | ---------------------------------------- | ------------------------------- |
 | **Controller层**  |                       |                                         |                                          |                                 |
 | Controller        | controller            | 类 class                                |                                          | controller.UserController       |
-| View Object       | controller/viewobject | 类 class                                | 将用户Model转化为可供UI使用的View Object | controller.UserController       |
+| View Object (VO)  | controller/viewobject | 类 class                                | 将用户Model转化为可供UI使用的View Object | controller.UserController       |
 |                   |                       |                                         |                                          |                                 |
 | **Service层**     | 转换成业务模型        |                                         |                                          |                                 |
 | Service           | service               | 接口 interface                          |                                          | service.UserService             |
@@ -28,7 +28,7 @@
 | **Dao层**         | 对数据库的映射        |                                         |                                          |                                 |
 | Mapper            | dao                   | 接口 interface                          |                                          | dao.UserDOMapper                |
 | Mapping           | resources/mapping     | Mapper接口实现类                        | xml格式；SQL语句                         | mapping/UserDOMapper.xml        |
-| Data Object       | dataobject            | 类 class                                |                                          | dataobject.UserDO               |
+| Data Object (DO)  | dataobject            | 类 class                                |                                          | dataobject.UserDO               |
 |                   |                       |                                         |                                          |                                 |
 | **其他**          |                       |                                         |                                          |                                 |
 | response          | response              |                                         | 用于处理HTTP请求返回                     | response.CommonReturnType       |
@@ -41,3 +41,27 @@
 | BusinessException | error                 | CommonError接口实现类 & 继承自Exception |                                          | error.BusinessException         |
 
 **Tips:** Model与Data Object并非完全一一对应，例如UserModel是由ServiceImpl将UserDO和UserPasswordDO组装而成的。
+
+
+
+代码构建顺序：
+
+1. 创建Model模型（service/model）
+
+2. 创建数据库中数据表
+
+3. 使用mybatis-generator生成数据库映射文件（dao ; dataobject ; resources/mapping）
+
+4. 创建Service接口（service）
+
+5. 创建Service接口实现Impl（service/impl）（class打上 `Service` 标注；方法上打上 `@Transactional` 标签保证是在同一事务中）
+
+6. 思考ServiceImpl中需要哪几步，并逐步实现
+
+   > - 如果需要修改自动生成的数据库语句，先改 resources/mapping 下的xml映射SQL语句，然后修改 dao 下的DOMapper接口
+   >
+   > - 可以用 `org.springframework.beans` 包中的 `BeanUtils.copyProperties` 进行DO转Model或Model转DO（要字段和类型完全一致的字段才能拷贝，其他不对应字段的需要手动设置）
+
+7. 
+
+8. Service返回Controller前将DO

src/main/java/com/cxyxiaomo/flashsale/dao/ItemStockDOMapper.java

@@ -1,6 +1,7 @@
 package com.cxyxiaomo.flashsale.dao;
 
 import com.cxyxiaomo.flashsale.dataobject.ItemStockDO;
+import org.apache.ibatis.annotations.Param;
 
 public interface ItemStockDOMapper {
     /**
@@ -52,4 +53,6 @@ public interface ItemStockDOMapper {
      * @mbg.generated Thu Mar 03 13:12:13 CST 2022
      */
     int updateByPrimaryKey(ItemStockDO record);
+
+    int decreaseStock(@Param("itemId") Integer itemId, @Param("amount") Integer amount);
 }

src/main/java/com/cxyxiaomo/flashsale/error/EmBusinessError.java

@@ -1,13 +1,16 @@
 package com.cxyxiaomo.flashsale.error;
 
 public enum EmBusinessError implements CommonError {
-    // 通用错误类型 00001
+    // 通用错误类型 10001
     PARAMETER_VALIDATION_ERROR(10001, "参数不合法"),
     UNKNOWN_ERROR(10002, "未知错误"),
 
-    // 10000开头为用户信息相关错误定义
+    // 20000开头为用户信息相关错误定义
     USER_NOT_EXIST(20001, "用户不存在"),
-    USER_LOGIN_FAILED(20002, "用户手机号或密码不正确");
+    USER_LOGIN_FAILED(20002, "用户手机号或密码不正确"),
+
+    // 30000开头为交易信息错误定义
+    STOCK_NOT_ENOUGH(30001, "库存不足");
 
     private EmBusinessError(int errCode, String errMsg) {
         this.errCode = errCode;

src/main/java/com/cxyxiaomo/flashsale/service/ItemService.java

@@ -14,4 +14,6 @@ public interface ItemService {
 
     // 商品详情浏览
     ItemModel getItemById(Integer id);
+
+    boolean decreaseStock(Integer itemId, Integer amount) throws BusinessException;
 }

src/main/java/com/cxyxiaomo/flashsale/service/OrderService.java

@@ -0,0 +1,15 @@
+package com.cxyxiaomo.flashsale.service;
+
+import com.cxyxiaomo.flashsale.error.BusinessException;
+import com.cxyxiaomo.flashsale.service.model.OrderModel;
+
+public interface OrderService {
+    /**
+     *
+     * @param userId 用户id
+     * @param itemId 购买商品
+     * @param amount 购买商品数量
+     * @return
+     */
+    OrderModel createOrder(Integer userId, Integer itemId, Integer amount) throws BusinessException;
+}

src/main/java/com/cxyxiaomo/flashsale/service/impl/ItemServiceImpl.java

@@ -103,6 +103,19 @@ public class ItemServiceImpl implements ItemService {
         return itemModel;
     }
 
+    @Override
+    @Transactional
+    public boolean decreaseStock(Integer itemId, Integer amount) throws BusinessException {
+        int affectedRow = itemStockDOMapper.decreaseStock(itemId, amount);
+        if (affectedRow > 0) {
+            // 更新库存成功
+            return true;
+        } else {
+            // 更新库存失败
+            return false;
+        }
+    }
+
     private ItemModel convertModelFromDataObject(ItemDO itemDO, ItemStockDO itemStockDO) {
         ItemModel itemModel = new ItemModel();
         BeanUtils.copyProperties(itemDO, itemModel);

src/main/java/com/cxyxiaomo/flashsale/service/impl/OrderServiceImpl.java

@@ -0,0 +1,95 @@
+package com.cxyxiaomo.flashsale.service.impl;
+
+import com.cxyxiaomo.flashsale.dao.OrderDOMapper;
+import com.cxyxiaomo.flashsale.dataobject.OrderDO;
+import com.cxyxiaomo.flashsale.error.BusinessException;
+import com.cxyxiaomo.flashsale.error.EmBusinessError;
+import com.cxyxiaomo.flashsale.service.ItemService;
+import com.cxyxiaomo.flashsale.service.OrderService;
+import com.cxyxiaomo.flashsale.service.UserService;
+import com.cxyxiaomo.flashsale.service.model.ItemModel;
+import com.cxyxiaomo.flashsale.service.model.OrderModel;
+import com.cxyxiaomo.flashsale.service.model.UserModel;
+import org.springframework.beans.BeanUtils;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.math.BigDecimal;
+
+@Service
+public class OrderServiceImpl implements OrderService {
+
+    @Autowired
+    private ItemService itemService;
+
+    @Autowired
+    private UserService userService;
+
+    @Autowired
+    private OrderDOMapper orderDOMapper;
+
+    @Override
+    @Transactional
+    public OrderModel createOrder(Integer userId, Integer itemId, Integer amount) throws BusinessException {
+        // 1. 校验下单状态
+        //  下单的商品是否存在；用户是否合法；购买数量是否正确
+        ItemModel itemModel = itemService.getItemById(itemId);
+        if (itemModel == null) {
+            throw new BusinessException(EmBusinessError.PARAMETER_VALIDATION_ERROR, "商品信息不存在");
+        }
+
+        UserModel userModel = userService.getUserById(userId);
+        if (userModel == null) {
+            throw new BusinessException(EmBusinessError.PARAMETER_VALIDATION_ERROR, "用户信息不存在");
+        }
+
+        if (amount <= 0 || amount > 99) {
+            throw new BusinessException(EmBusinessError.PARAMETER_VALIDATION_ERROR, "数量信息不正确");
+        }
+
+        // 2. 落单减库存 / 支付减库存(有可能超卖)
+        boolean result = itemService.decreaseStock(itemId, amount);
+        if (!result) {
+            throw new BusinessException(EmBusinessError.STOCK_NOT_ENOUGH);
+        }
+
+        // 3. 订单入库
+        OrderModel orderModel = new OrderModel();
+        orderModel.setUserId(userId);
+        orderModel.setItemId(itemId);
+        orderModel.setAmount(amount);
+        orderModel.setItemPrice(itemModel.getPrice());
+        orderModel.setOrderPrice(itemModel.getPrice().multiply(new BigDecimal(amount)));
+
+        // 生成交易流水号，订单号
+
+        OrderDO orderDO = convertFromOrderModel(orderModel);
+        orderDOMapper.insertSelective(orderDO);
+
+        // 4. 返回前端
+
+        return null;
+    }
+
+    private OrderDO convertFromOrderModel(OrderModel orderModel) {
+        if (orderModel == null) {
+            return null;
+        }
+        OrderDO orderDO = new OrderDO();
+        BeanUtils.copyProperties(orderModel, orderDO);
+
+        return orderDO;
+    }
+
+    // 生成交易流水号，订单号
+    private String generateOderNo(){
+        // 订单号为16位
+        // 前8位为时间信息（年月日）
+
+        // 中间6位为自增序列
+
+        // 最后2位为分库分表位
+
+    }
+}

src/main/resources/mapping/ItemStockDOMapper.xml

@@ -114,4 +114,10 @@
     from item_stock
     where item_id = #{itemId,jdbcType=INTEGER}
   </select>
+  <update id="decreaseStock">
+    update item_stock
+    set stock = stock - #{amount},
+    item_id = #{itemId}
+    where item_id = #{itemId} and stock >= #{amount}
+  </update>
 </mapper>