使用 AI 辅助开发 Java 电商系统核心模块实战

四、接口设计与代码生成

表结构确认后，AI 可自动生成 Controller、Service、Mapper 层代码。

1. 商品管理核心接口（Controller 层）

package com.example.ecommerce.controller;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.ecommerce.common.Result;
import com.example.ecommerce.entity.Product;
import com.example.ecommerce.service.ProductService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.*;
import javax.annotation.Resource;
import java.util.List;

@RestController
@RequestMapping("/api/product")
@Slf4j
public class ProductController {
    @Resource
    private ProductService productService;

    /**
     * 新增商品
     */
    @PostMapping("/add")
    public Result<?> addProduct(@RequestBody Product product) {
        if (product.getPrice().compareTo(java.math.BigDecimal.ZERO) < 0) {
            return Result.fail("商品价格不能为负");
        }
        if (product.getStock() < 0) {
            return Result.fail("商品库存不能为负");
        }
        product.setStatus(1);
        boolean success = productService.save(product);
        if (success) {
            log.info("新增商品成功，商品 ID：{}", product.getId());
            return Result.success("新增商品成功", product.getId());
        }
        return Result.fail("新增商品失败");
    }

    /**
     * 商品列表查询
     */
    @GetMapping("/list")
    public Result<?> getProductList(
            @RequestParam(required = false) String productName,
            @RequestParam(defaultValue = "1") Integer pageNum,
            @RequestParam(defaultValue = "10") Integer pageSize,
            @RequestParam(defaultValue = "id") String sortField,
            @RequestParam(defaultValue = "desc") String sortType) {
        Page<Product> page = new Page<>(pageNum, pageSize);
        List<Product> productList = productService.getProductList(page, productName, sortField, sortType);
        page.setRecords(productList);
        log.info("查询商品列表成功，页码：{}，条数：{}", pageNum, productList.size());
        return Result.success("查询成功", page);
    }

    /**
     * 商品上下架
     */
    @PutMapping("/status")
    public Result<?> updateProductStatus(@RequestParam Long productId, @RequestParam Integer status) {
        if (!status.equals(0) && !status.equals(1)) {
            return Result.fail("状态只能是 0（下架）或 1（上架）");
        }
        Product product = new Product();
        product.setId(productId);
        product.setStatus(status);
        boolean success = productService.updateById(product);
        if (success) {
            String msg = status == 1 ? "商品上架成功" : "商品下架成功";
            log.info(msg + "，商品 ID：{}", productId);
            return Result.success(msg);
        }
        return Result.fail("修改商品状态失败");
    }
}

2. 购物车核心接口（Redis 存储）

package com.example.ecommerce.controller;

import com.example.ecommerce.common.Result;
import com.example.ecommerce.entity.vo.CartVO;
import com.example.ecommerce.service.CartService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.*;
import javax.annotation.Resource;
import java.math.BigDecimal;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/api/cart")
@Slf4j
public class CartController {
    @Resource
    private CartService cartService;

    /**
     * 添加商品到购物车
     */
    @PostMapping("/add")
    public Result<?> addToCart(@RequestParam Long userId, @RequestParam Long productId, @RequestParam Integer buyNum) {
        String checkMsg = cartService.checkBeforeAdd(userId, productId, buyNum);
        if (checkMsg != null) {
            return Result.fail(checkMsg);
        }
        boolean success = cartService.addCart(userId, productId, buyNum);
        if (success) {
            log.info("添加购物车成功，用户 ID：{}，商品 ID：{}", userId, productId);
            return Result.success("添加购物车成功");
        }
        return Result.fail("添加购物车失败");
    }

    /**
     * 查询用户购物车列表
     */
    @GetMapping("/list")
    public Result<?> getCartList(@RequestParam Long userId) {
        List<CartVO> cartVOList = cartService.getCartList(userId);
        BigDecimal totalAmount = cartVOList.stream()
                .map(CartVO::getSubtotal)
                .reduce(BigDecimal.ZERO, BigDecimal::add);
        Map<String, Object> data = new HashMap<>();
        data.put("cartList", cartVOList);
        data.put("totalAmount", totalAmount);
        return Result.success("查询购物车成功", data);
    }

    /**
     * 修改购物车商品数量
     */
    @PutMapping("/num")
    public Result<?> updateCartNum(@RequestParam Long userId, @RequestParam Long productId, @RequestParam Integer newNum) {
        if (newNum <= 0) {
            return Result.fail("数量不能小于等于 0");
        }
        String checkMsg = cartService.checkStock(productId, newNum);
        if (checkMsg != null) {
            return Result.fail(checkMsg);
        }
        boolean success = cartService.updateCartNum(userId, productId, newNum);
        if (success) {
            log.info("修改数量成功，用户 ID：{}，商品 ID：{}，新数量：{}", userId, productId, newNum);
            return Result.success("修改数量成功");
        }
        return Result.fail("修改数量失败");
    }
}

3. 订单核心接口（含库存扣减与幂等校验）

package com.example.ecommerce.controller;

import com.example.ecommerce.common.Result;
import com.example.ecommerce.entity.OrderInfo;
import com.example.ecommerce.entity.vo.OrderDetailVO;
import com.example.ecommerce.service.OrderService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.*;
import javax.annotation.Resource;
import java.util.List;

@RestController
@RequestMapping("/api/order")
@Slf4j
public class OrderController {
    @Resource
    private OrderService orderService;

    /**
     * 创建订单
     */
    @PostMapping("/create")
    public Result<?> createOrder(@RequestParam Long userId, @RequestParam String productIds) {
        String requestId = userId + "_" + System.currentTimeMillis();
        boolean isRepeat = orderService.checkRepeatRequest(requestId);
        if (isRepeat) {
            return Result.fail("请勿重复提交订单");
        }
        try {
            String orderNo = orderService.createOrder(userId, productIds);
            log.info("创建订单成功，用户 ID：{}，订单编号：{}", userId, orderNo);
            return Result.success("创建订单成功", orderNo);
        } catch (Exception e) {
            log.error("创建订单失败，用户 ID：{}，错误信息：{}", userId, e.getMessage());
            return Result.fail("创建订单失败：" + e.getMessage());
        }
    }

    /**
     * 查询订单列表
     */
    @GetMapping("/list")
    public Result<?> getOrderList(@RequestParam Long userId, @RequestParam(defaultValue = "1") Integer pageNum, @RequestParam(defaultValue = "10") Integer pageSize) {
        List<OrderInfo> orderList = orderService.getOrderList(userId, pageNum, pageSize);
        log.info("查询订单列表成功，用户 ID：{}，订单数量：{}", userId, orderList.size());
        return Result.success("查询订单列表成功", orderList);
    }

    /**
     * 查询订单明细
     */
    @GetMapping("/detail")
    public Result<?> getOrderDetail(@RequestParam String orderNo, @RequestParam Long userId) {
        OrderDetailVO orderDetail = orderService.getOrderDetail(orderNo, userId);
        if (orderDetail == null) {
            return Result.fail("订单不存在或无权限查看");
        }
        return Result.success("查询订单明细成功", orderDetail);
    }

    /**
     * 修改订单支付状态
     */
    @PutMapping("/payStatus")
    public Result<?> updatePayStatus(@RequestParam String orderNo, @RequestParam Long userId, @RequestParam Integer payStatus) {
        if (!payStatus.equals(1) && !payStatus.equals(2)) {
            return Result.fail("支付状态只能是 1（已支付）或 2（已取消）");
        }
        String checkMsg = orderService.checkOrderBeforeUpdate(orderNo, userId);
        if (checkMsg != null) {
            return Result.fail(checkMsg);
        }
        boolean success = orderService.updatePayStatus(orderNo, payStatus);
        if (success) {
            String msg = payStatus == 1 ? "订单支付成功" : "订单取消成功";
            log.info("{}，订单编号：{}，用户 ID：{}", msg, orderNo, userId);
            return Result.success(msg);
        }
        return Result.fail("修改支付状态失败");
    }
}

4. 核心 Service 层代码示例

以订单创建为例，AI 自动处理了事务管理、库存扣减和订单编号生成。

package com.example.ecommerce.service.impl;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.example.ecommerce.entity.*;
import com.example.ecommerce.entity.vo.CartVO;
import com.example.ecommerce.mapper.*;
import com.example.ecommerce.service.CartService;
import com.example.ecommerce.service.OrderService;
import com.example.ecommerce.service.ProductService;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.math.BigDecimal;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.List;
import java.util.Random;
import java.util.concurrent.TimeUnit;

@Service
public class OrderServiceImpl implements OrderService {
    @Resource
    private OrderInfoMapper orderInfoMapper;
    @Resource
    private OrderItemMapper orderItemMapper;
    @Resource
    private ProductMapper productMapper;
    @Resource
    private CartService cartService;
    @Resource
    private RedisTemplate<String, Object> redisTemplate;

    /**
     * 创建订单
     */
    @Override
    @Transactional(rollbackFor = Exception.class)
    public String createOrder(Long userId, String productIds) {
        List<CartVO> cartVOList = cartService.getCheckedCartList(userId, productIds);
        if (cartVOList.isEmpty()) {
            throw new RuntimeException("购物车中无选中商品");
        }

        BigDecimal totalAmount = cartVOList.stream()
                .map(CartVO::getSubtotal)
                .reduce(BigDecimal.ZERO, BigDecimal::add);

        String orderNo = generateOrderNo();

        for (CartVO cartVO : cartVOList) {
            Long productId = cartVO.getProductId();
            Integer buyNum = cartVO.getBuyNum();
            Product product = productMapper.selectByIdForUpdate(productId);
            if (product == null || product.getStatus() == 0) {
                throw new RuntimeException("商品" + cartVO.getProductName() + "已下架或不存在");
            }
            if (product.getStock() < buyNum) {
                throw new RuntimeException("商品" + cartVO.getProductName() + "库存不足");
            }
            Product updateProduct = new Product();
            updateProduct.setId(productId);
            updateProduct.setStock(product.getStock() - buyNum);
            productMapper.updateById(updateProduct);
        }

        OrderInfo orderInfo = new OrderInfo();
        orderInfo.setOrderNo(orderNo);
        orderInfo.setUserId(userId);
        orderInfo.setTotalAmount(totalAmount);
        orderInfo.setPayStatus(0);
        orderInfo.setOrderStatus(0);
        orderInfo.setCreateTime(LocalDateTime.now());
        orderInfoMapper.insert(orderInfo);

        for (CartVO cartVO : cartVOList) {
            OrderItem orderItem = new OrderItem();
            orderItem.setOrderId(orderInfo.getId());
            orderItem.setOrderNo(orderNo);
            orderItem.setProductId(cartVO.getProductId());
            orderItem.setProductName(cartVO.getProductName());
            orderItem.setProductPrice(cartVO.getProductPrice());
            orderItem.setBuyNum(cartVO.getBuyNum());
            orderItem.setCreateTime(LocalDateTime.now());
            orderItemMapper.insert(orderItem);
        }

        cartService.clearCheckedCart(userId, productIds);
        return orderNo;
    }

    private String generateOrderNo() {
        String timeStr = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMMddHHmmss"));
        String randomStr = String.format("%06d", new Random().nextInt(1000000));
        return timeStr + randomStr;
    }

    @Override
    public boolean checkRepeatRequest(String requestId) {
        String redisKey = "order:repeat:" + requestId;
        if (Boolean.TRUE.equals(redisTemplate.hasKey(redisKey))) {
            return true;
        }
        redisTemplate.opsForValue().set(redisKey, "1", 5, TimeUnit.MINUTES);
        return false;
    }
}

五、测试与优化建议

1. 接口测试

启动项目后，可使用 Postman 验证接口。例如调用 POST /api/cart/add，传入 userId, productId, buyNum。若参数异常，AI 生成的异常处理逻辑会返回明确提示。

2. 常见优化方向

通过 AI 分析，可进一步提出以下优化建议：

1. 库存预热：高并发场景下，将热门商品库存缓存至 Redis。
2. 订单超时取消：使用定时任务扫描未支付订单，自动取消并恢复库存。
3. 接口限流：对创建订单接口增加限流保护，防止恶意请求。

六、总结

利用 AI 辅助开发，可将原本需要数天的工作压缩至几小时内完成。开发者只需专注于需求梳理和结果验证，AI 负责生成规范的代码、处理边界条件和提供优化建议。这种模式不仅提升了效率，也降低了技术门槛，适合快速构建电商系统等复杂业务场景。