一. 删除购物车中一个商品
删除商品时我们要考虑一个问题，当商品数量等于1时，删除商品就直接将其从数据库中删除即可。但是当数量大于1时，删除商品就是让商品数量-1。因此我们在删除一个商品时首先要判断该商品在购物车中的数量。
Controller层
package com.sky.controller.user;import com.sky.context.BaseContext;
import com.sky.dto.ShoppingCartDTO;
import com.sky.entity.ShoppingCart;
import com.sky.result.Result;
import com.sky.service.ShoppingCartService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;import java.util.List;@RestController
@RequestMapping("/user/shoppingCart")
@Slf4j
@Api(tags = "购物车相关接口")
public class ShoppingCartController {@Autowiredprivate ShoppingCartService shoppingCartService;/*** 添加购物车* @param shoppingCartDTO* @return*/@ApiOperation("添加购物车")@PostMapping("/add")public Result add(@RequestBody ShoppingCartDTO shoppingCartDTO) {log.info("向购物车中添加菜品或套餐：{}",shoppingCartDTO);shoppingCartService.add(shoppingCartDTO);return Result.success();}/*** 查看购物车* @return*/@GetMapping("/list")@ApiOperation("查看购物车")public Result<List<ShoppingCart>> list() {log.info("查看购物车：{}", BaseContext.getCurrentId());List<ShoppingCart> list = shoppingCartService.showShoppingCart();return Result.success(list);}/*** 清空购物车* @return*/@DeleteMapping("/clean")@ApiOperation("清空购物车")public Result clean() {log.info("清空购物车：{}",BaseContext.getCurrentId());shoppingCartService.cleanShoppingCart();return Result.success();}/*** 删除购物车中一个商品* @param shoppingCartDTO* @return*/@PostMapping("/sub")@ApiOperation("删除购物车中一个商品")public Result delete(@RequestBody ShoppingCartDTO shoppingCartDTO) {shoppingCartService.deleteShoppingCart(shoppingCartDTO);return Result.success();}
}
Service层
接口
package com.sky.service;import com.sky.dto.ShoppingCartDTO;
import com.sky.entity.ShoppingCart;
import org.springframework.stereotype.Service;import java.util.List;@Service
public interface ShoppingCartService {/*** 添加购物车* @param shoppingCartDTO*/void add(ShoppingCartDTO shoppingCartDTO);/*** 查查看购物车* @return*/List<ShoppingCart> showShoppingCart();/*** 清空购物车*/void cleanShoppingCart();/*** 删除购物车中一个商品* @param shoppingCartDTO*/void deleteShoppingCart(ShoppingCartDTO shoppingCartDTO);
}
实现类
package com.sky.service.impl;import com.sky.context.BaseContext;
import com.sky.dto.ShoppingCartDTO;
import com.sky.entity.Dish;
import com.sky.entity.Setmeal;
import com.sky.entity.ShoppingCart;
import com.sky.mapper.DishMapper;
import com.sky.mapper.SetmealMapper;
import com.sky.mapper.ShoppingCartMapper;
import com.sky.service.ShoppingCartService;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.time.LocalDateTime;
import java.util.List;@Service
public class ShoppingCartServiceImpl implements ShoppingCartService {@Autowiredprivate ShoppingCartMapper shoppingCartMapper;@Autowiredprivate DishMapper dishMapper;@Autowiredprivate SetmealMapper setmealMapper;/*** 添加购物车* @param shoppingCartDTO*/@Overridepublic void add(ShoppingCartDTO shoppingCartDTO) {// 首先判断这次添加购物车的操作加入的菜品或套餐是否已经存在，如果存在就把份数+1，如果不存在就新增ShoppingCart shoppingCart = new ShoppingCart();BeanUtils.copyProperties(shoppingCartDTO,shoppingCart);Long userId = BaseContext.getCurrentId();shoppingCart.setUserId(userId);// 1.首先查询该菜品或套餐在数据库中是否存在List<ShoppingCart> list = shoppingCartMapper.list(shoppingCart); // 每次添加的要么是菜品，要么是套餐。且如果重复添加只会增加份数而不会新增一条数据，因此每次查询要么为空，要么查询出1条数据if (list != null && list.size() > 0) { // 已存在，数量+1ShoppingCart cart = list.get(0); // 将已存在的购物车对象取出cart.setNumber(cart.getNumber() + 1); // 并将其菜品/套餐数量+1shoppingCartMapper.updateNumberById(cart); // 通过id更新} else {// 2.不存在，先判断是套餐还是菜品，因为套餐和菜品在购物车中所需要的属性是不一样的Long dishId = shoppingCartDTO.getDishId();if (dishId != null) {// 3.如果是菜品，那么从菜品数据库中查找并将对应属性赋值给购物车对象Dish dish = dishMapper.getById(dishId);shoppingCart.setName(dish.getName());shoppingCart.setImage(dish.getImage());shoppingCart.setAmount(dish.getPrice());} else {// 4.如果是套餐，那么从套餐数据库中查找并将对应属性赋值给购物车对象Long setmealId = shoppingCartDTO.getSetmealId();Setmeal setmeal = setmealMapper.getById(setmealId);shoppingCart.setName(setmeal.getName());shoppingCart.setImage(setmeal.getImage());shoppingCart.setAmount(setmeal.getPrice());}// 5.将新增的菜品/套餐加入数据库中shoppingCart.setNumber(1);shoppingCart.setCreateTime(LocalDateTime.now());shoppingCartMapper.insert(shoppingCart);}}/*** 查看购物车* @return*/@Overridepublic List<ShoppingCart> showShoppingCart() {Long userId = BaseContext.getCurrentId();ShoppingCart shoppingCart = ShoppingCart.builder().userId(userId).build();List<ShoppingCart> list = shoppingCartMapper.list(shoppingCart);return list;}/*** 清空购物车*/@Overridepublic void cleanShoppingCart() {Long userId = BaseContext.getCurrentId();shoppingCartMapper.cleanByUserId(userId);}/*** 删除购物车中一个商品* @param shoppingCartDTO*/@Overridepublic void deleteShoppingCart(ShoppingCartDTO shoppingCartDTO) {// 在删除购物车中的商品时，首先要判断该商品的数量是否大于1。如果大于1，那么就使得该商品的数量-1(update)。如果等于1，那么就删除该商品ShoppingCart shoppingCart = new ShoppingCart();BeanUtils.copyProperties(shoppingCartDTO,shoppingCart);Long userId = BaseContext.getCurrentId();shoppingCart.setUserId(userId);List<ShoppingCart> list = shoppingCartMapper.list(shoppingCart);ShoppingCart cart = list.get(0);// 等于1，直接删除if (cart.getNumber() == 1 ) {shoppingCartMapper.delete(cart.getId());} else {// // 大于1，数量-1cart.setNumber(cart.getNumber() - 1);shoppingCartMapper.updateNumberById(cart);}}
}
在删除时我们根据id进行删除。在查询到该商品之后首先进行数量判断，等于1则直接获取其id并根据id删除。这里执行的是delete操作。
如果大于1我们执行更新操作，即将该商品数量-1更新到数据库中。
Mapper层
package com.sky.mapper;import com.sky.dto.ShoppingCartDTO;
import com.sky.entity.ShoppingCart;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Update;import java.util.List;@Mapper
public interface ShoppingCartMapper {/*** 查询菜品/套餐是否存在* @param shoppingCart* @return*/List<ShoppingCart> list(ShoppingCart shoppingCart);/*** 更新购物车中套餐/菜品份数* @param shoppingCart*/@Update("update shopping_cart set number = #{number} where id = #{id}")void updateNumberById(ShoppingCart shoppingCart);/*** 向购物车中加入菜品/套餐* @param shoppingCart*/@Insert("insert into shopping_cart(name, image, user_id, dish_id, setmeal_id, dish_flavor, number, amount, create_time) " +"VALUES (#{name}, #{image}, #{userId}, #{dishId}, #{setmealId}, #{dishFlavor}, #{number}, #{amount},#{createTime})")void insert(ShoppingCart shoppingCart);/*** 清空购物车* @param userId*/@Delete("delete from shopping_cart where user_id = #{userId}")void cleanByUserId(Long userId);/*** 删除购物车中一个商品* @param id*/@Delete("delete from shopping_cart where id = #{id}")void delete(Long id);
}
