使用 AI 辅助开发 Java 电商核心功能实战：商品、购物车与订单系统

三、核心功能实现

1. 商品管理接口

控制器层包含新增、查询、上下架接口。AI 已内置参数校验逻辑，确保价格和库存不为负。

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);
    }
}

2. 购物车接口

采用 Redis 存储以提升性能。Controller 层主要处理添加、查询和修改数量的逻辑。

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(java.math.BigDecimal.ZERO, java.math.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);
    }
}

3. 订单服务实现

订单创建涉及库存扣减、事务管理和幂等校验。这是业务逻辑最复杂的部分。

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（事务保证）
     */
    @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;
    }
}

四、测试与优化建议

1. 接口测试

启动项目后，使用 Postman 调用接口验证。例如添加商品到购物车：

• 请求地址：http://localhost:8080/api/cart/add
• 请求方式：POST
• 参数：userId=1&productId=1&buyNum=2
• 预期响应：{"code": 200, "msg": "添加购物车成功", "data": null}

若参数有误（如库存不足），AI 生成的异常处理会返回明确提示。

2. 性能优化

针对高并发场景，AI 可提供进一步优化建议，例如：

• 库存预热：将热门商品库存缓存至 Redis。
• 订单超时取消：通过定时任务扫描未支付订单并恢复库存。

以下是订单超时取消的定时任务示例：

package com.example.ecommerce.task;

import com.example.ecommerce.entity.OrderInfo;
import com.example.ecommerce.mapper.OrderInfoMapper;
import com.example.ecommerce.mapper.OrderItemMapper;
import com.example.ecommerce.mapper.ProductMapper;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.List;

@Component
public class OrderTimeoutTask {

    @Resource
    private OrderInfoMapper orderInfoMapper;
    @Resource
    private OrderItemMapper orderItemMapper;
    @Resource
    private ProductMapper productMapper;

    /**
     * 每 5 分钟执行一次：查询超过 30 分钟未支付的订单
     */
    @Scheduled(cron = "0 0/5 * * * ?")
    @Transactional(rollbackFor = Exception.class)
    public void cancelTimeoutOrder() {
        LocalDateTime timeoutTime = LocalDateTime.now().minusMinutes(30);
        List<OrderInfo> timeoutOrders = orderInfoMapper.selectTimeoutOrders(0, timeoutTime);
        for (OrderInfo order : timeoutOrders) {
            order.setPayStatus(2);
            order.setUpdateTime(LocalDateTime.now());
            orderInfoMapper.updateById(order);

            List<OrderItem> orderItems = orderItemMapper.selectByOrderId(order.getId());
            for (OrderItem item : orderItems) {
                Product product = productMapper.selectById(item.getProductId());
                product.setStock(product.getStock() + item.getBuyNum());
                productMapper.updateById(product);
            }
        }
    }
}

总结

整个开发过程仅需需求沟通、建表、测试三个主要环节。AI 承担了大部分重复性工作，包括表结构设计、代码编写、异常处理及优化建议。这种方式让开发者不再需要死磕重复代码，而是将精力集中在更有价值的业务设计上。