苍穹外卖day7 缓存商品（redis/Spring Cache）、用户端购物车功能-三、购物车管理

1. 添加购物车

1.1 产品原型

1.2 接口设计

1.3 数据库设计

暂时存放所选商品的地方
选的什么商品
每个商品都买了几个
不同用户的购物车需要区分开

1.4 代码开发

1、在ShoppingCartController中编写add方法添加购物车

@PostMapping("/add")
@ApiOperation("添加购物车")
private Result add(@RequestBody ShoppingCartDTO shoppingCartDTO){
    log.info("添加购物车，商品信息为：{}",shoppingCartDTO);
    shoppingCartService.addShoppingCart(shoppingCartDTO);
    return Result.success();
}

2、在ShoppingCartService中定义addShoppingCart方法，在ShoppingCarterviceImpl中实现

 public void addShoppingCart(ShoppingCartDTO shoppingCartDTO) {
    //判断当前加入购物车中的商品已存在
    ShoppingCart shoppingCart = new ShoppingCart();
    BeanUtils.copyProperties(shoppingCartDTO,shoppingCart);
    //获取用户id
    Long userId = BaseContext.getCurrentId();
    shoppingCart.setUserId(userId);
    //通过list方法查询购物车中的商品
    List<ShoppingCart> list = shoppingCartMapper.list(shoppingCart);

    //如果已存在，只需要将数量加1
    if(list != null && list.size()>0){
        ShoppingCart cart = list.get(0);
        cart.setNumber(cart.getNumber()+1);
        //update shopping_cart set number =? where id = ?
        shoppingCartMapper.updateNumberById(cart);
    }else{
        //如果不存在，需要插入一条购物车数据
        //判断本次添加到购物车中商品的是菜品还是套餐
        Long dishId = shoppingCartDTO.getDishId();
        if(dishId != null){
            //本次添加到购物车的是菜品
            //查询菜品信息
            Dish dish = dishMapper.getById(dishId);
            shoppingCart.setName(dish.getName());
            shoppingCart.setImage(dish.getImage());
            shoppingCart.setAmount(dish.getPrice());
        }else{
            Long setmealId = shoppingCart.getSetmealId();
            //本次添加到购物车的是套餐
            Setmeal setmeal = setmealMapper.getById(setmealId);
            shoppingCart.setName(setmeal.getName());
            shoppingCart.setImage(setmeal.getImage());
            shoppingCart.setAmount(setmeal.getPrice());
        }
        shoppingCart.setNumber(1);
        shoppingCart.setCreateTime(LocalDateTime.now());
        shoppingCartMapper.insert(shoppingCart);
    }
}

3、在ShoppingCartMapper中定义list、updateNumberById、insert方法，在ShoppingCartMapper.xml文件中编写sql语句，完成相应的业务逻辑

//动态条件查询
List<ShoppingCart> list(ShoppingCart shoppingCart);
//根据id修改商品数量
@Update("update sky_take_out.shopping_cart set number=#{number} where id=#{id}")
void updateNumberById(ShoppingCart shoppingCart);
//插入购物车数据
@Insert("insert into sky_take_out.shopping_cart(name, image, user_id, dish_id, setmeal_id, "+
       "dish_flavor, amount, create_time)  values " +
       "(#{name}, #{image}, #{userId}, #{dishId}, #{setmealId}, #{dishFlavor}, #{amount}, #{createTime})")
void insert(ShoppingCart shoppingCart);

<select id="list" resultType="com.sky.entity.ShoppingCart">
    select * from sky_take_out.shopping_cart
	<where>
	    <if test="userId != null">and user_id = #{userId}</if>
	    <if test="setmealId != null">and setmeal_id = #{setmealId}</if>
	    <if test="dishId != null">and dish_id = #{dishId}</if>
	    <if test="dishFlavor != null">and dish_flavor = #{dishFlavor}</if>
	</where>
</select>

2. 查看购物车

2.1 接口设计

2.2 代码开发

1、在ShoppingCartController中创建查看购物车的方法

 @GetMapping("/list")
 @ApiOperation("查看购物车")
  public Result<List<ShoppingCart>> list(){
      List<ShoppingCart> list = shoppingCartService.showShoppingCart();
      return Result.success(list);
  }

2、在ShoppingCartService接口中声明查看购物车的方法，在ShoppingCartServiceImpl中实现方法

public List<ShoppingCart> showShoppingCart() {
        //获取当前用户id
        Long userId = BaseContext.getCurrentId();
        ShoppingCart shoppingCart = ShoppingCart.builder()
                .userId(userId)
                .build();
        //list方法在添加购物车时已实现
        List<ShoppingCart> list = shoppingCartMapper.list(shoppingCart);
        return list;
    }

3. 清空购物车

3.1 接口设计

3.2 代码开发

1、在ShoppingCartController中创建清空购物车的方法，直接获取当前用户id，将当前用户的购物车数据全部删除

 public void cleanShoppingCart() {
   //获取当前用户id
    Long userId = BaseContext.getCurrentId();
    shoppingCartMapper.deleteByUserId(userId);
}

2、在ShoppingCartService接口中声明清空购物车的方法，在ShoppingCartServiceImpl中实现方法

public void cleanShoppingCart() {
    shoppingCartMapper.deleteByUserId(BaseContext.getCurrentId());
}

3、在ShoppingCartMapper接口中创建删除购物车数据的方法

 @Delete("delete from sky_take_out.shopping_cart where user_id=#{userId}")
 void deleteByUserId(Long userId);

4. 删除购物车中一个商品

4.1 接口设计

4.2 代码开发

1、在ShoppingCartController中创建删除购物车中一个商品的方法

@PostMapping("/sub")
@ApiOperation("删除购物车中一个商品")
public Result sub(@RequestBody ShoppingCartDTO shoppingCartDTO){
    log.info("删除购物车中一个商品，商品：{}", shoppingCartDTO);
    shoppingCartService.subShoppingCart(shoppingCartDTO);
    return Result.success();
}

2、在ShoppingCartService接口中声明方法，在ShoppingCartServiceImpl中实现，这里需要判断此商品数量为1还是大于1，该商品数量为1的时候直接删除，不为1则修改份数

public void subShoppingCart(ShoppingCartDTO shoppingCartDTO) {
    ShoppingCart shoppingCart = new ShoppingCart();
    BeanUtils.copyProperties(shoppingCartDTO,shoppingCart);
    //设置查询条件，查询当前登录用户的购物车数据
    shoppingCart.setUserId(BaseContext.getCurrentId());
    List<ShoppingCart> list = shoppingCartMapper.list(shoppingCart);
    if(list != null && list.size() > 0){
        shoppingCart = list.get(0);
        Integer number = shoppingCart.getNumber();
        if(number == 1){
            //当前商品在购物车中的份数为1，直接删除当前记录
            shoppingCartMapper.deleteById(shoppingCart.getId());
        }else {
            //当前商品在购物车中的份数不为1，修改份数即可
            shoppingCart.setNumber(shoppingCart.getNumber() - 1);
            shoppingCartMapper.updateNumberById(shoppingCart);//在添加购物车的时候已实现
        }
    }
}

3、在ShoppingCartMapper中定义deleteById方法

@Delete("delete from shopping_cart where id = #{id}")
void deleteById(Long id);