Initial commit: backend code

src/main/java/com/example/building/dto/CreateOrderRequest.java

@@ -0,0 +1,68 @@
+package com.example.building.dto;
+
+import lombok.Data;
+
+import javax.validation.constraints.NotEmpty;
+import javax.validation.constraints.NotNull;
+import java.math.BigDecimal;
+import java.util.List;
+
+/**
+ * 创建订单请求DTO
+ * 核心业务逻辑：
+ * 1. 计算订单原价(total_amount) = Σ(item.price × item.quantity)
+ * 2. 计算优惠金额(discount_amount) = total_amount × (100 - discount_rate) / 100
+ * 3. 计算实付金额(actual_amount) = total_amount - discount_amount
+ */
+@Data
+public class CreateOrderRequest {
+
+    /**
+     * 客户ID
+     */
+    private String customerId;
+
+    /**
+     * 订单明细
+     */
+    @NotEmpty(message = "订单明细不能为空")
+    private List<OrderItemDTO> items;
+
+    /**
+     * 折扣率(百分比), 默认100
+     */
+    private BigDecimal discountRate;
+
+    /**
+     * 备注
+     */
+    private String remark;
+
+    /**
+     * 支付方式
+     */
+    private String paymentMethod;
+
+    /**
+     * 订单明细项DTO
+     */
+    @Data
+    public static class OrderItemDTO {
+        /**
+         * 商品ID
+         */
+        @NotBlank(message = "商品ID不能为空")
+        private String productId;
+
+        /**
+         * 数量
+         */
+        @NotNull(message = "数量不能为空")
+        private Integer quantity;
+
+        /**
+         * 销售单价(用户可自定义)
+         */
+        private BigDecimal price;
+    }
+}