Java电商项目面试--订单模块

灰太狼 2021-09-27 08:40 614阅读 0赞

> **面试：订单模块技术要点**  
> **技术要点：  
> 1、安全漏洞解决方案  
> 2、订单号生成规则  
> 3、强大的常量、枚举设计**

**一、前台创建订单**  
Controller层：

//创建订单
    @RequestMapping("create.do")
    @ResponseBody
    public ServerResponse create(HttpSession session, Integer shippingId){
        User user = (User)session.getAttribute(Const.CURRENT_USER);
        if(user ==null)
            return ServerResponse.createByErrorCodeMessage(ResponseCode.NEED_LOGIN.getCode(),ResponseCode.NEED_LOGIN.getDesc());
        return iOrderService.createOrder(user.getId(),shippingId);
    }

Service层：

//创建订单
    public  ServerResponse createOrder(Integer userId,Integer shippingId){
        //从购物车中获取已经被勾选的商品
        List<Cart> cartList = cartMapper.selectCheckedCartByUserId(userId);
        //校验并封装一下
        ServerResponse serverResponse = this.getCartOrderItem(userId,cartList);
        if(!serverResponse.isSuccess())
            return serverResponse;
        List<OrderItem> orderItemList = (List<OrderItem>)serverResponse.getData();
        //计算这个订单的总价
        BigDecimal payment = this.getOrderTotalPrice(orderItemList);
        //生成订单
        Order order = this.assembleOrder(userId,shippingId,payment);
        if(order == null)
            return ServerResponse.createByErrorMessage("生成订单错误");
        if(CollectionUtils.isEmpty(orderItemList))
            return ServerResponse.createByErrorMessage("购物车为空");
        //每一项都生成订单号
        for(OrderItem orderItem : orderItemList)
            //设置订单号
            orderItem.setOrderNo(order.getOrderNo());
    
        //mybatis 批量插入
        orderItemMapper.batchInsert(orderItemList);
        //生成成功,我们要减少我们产品的库存
        this.reduceProductStock(orderItemList);
        //清空一下购物车
        this.cleanCart(cartList);
        //返回给前端数据
        OrderVo orderVo = assembleOrderVo(order,orderItemList);
        return ServerResponse.createBySuccess(orderVo);
    }
    //校验并且封装一下
    private ServerResponse getCartOrderItem(Integer userId,List<Cart> cartList){
        List<OrderItem> orderItemList = Lists.newArrayList();
        //购物车中已经勾选的商品是空的
        if(CollectionUtils.isEmpty(cartList))
            return ServerResponse.createByErrorMessage("购物车为空");
        /*********校验购物车的数据,包括产品的状态和数量********/
        for(Cart cartItem : cartList){
            OrderItem orderItem = new OrderItem();
            //查出商品
            Product product = productMapper.selectByPrimaryKey(cartItem.getProductId());
            //查看产品销售状态
            if(Const.ProductStatusEnum.ON_SALE.getCode() != product.getStatus()){
                return ServerResponse.createByErrorMessage("产品"+product.getName()+"不是在线售卖状态");
            }
            //校验库存
            if(cartItem.getQuantity() > product.getStock()){
                return ServerResponse.createByErrorMessage("产品"+product.getName()+"库存不足");
            }
            /**********将已经勾选的购物车中的商品组装一下***********/
            orderItem.setUserId(userId);
            orderItem.setProductId(product.getId());
            orderItem.setProductName(product.getName());
            orderItem.setProductImage(product.getMainImage());
            orderItem.setCurrentUnitPrice(product.getPrice());
            orderItem.setQuantity(cartItem.getQuantity());
            //此项商品的总价
            orderItem.setTotalPrice(BigDecimalUtil.mul(product.getPrice().doubleValue(),cartItem.getQuantity()));
            orderItemList.add(orderItem);
        }
        return ServerResponse.createBySuccess(orderItemList);
    }
    //此函数用于计算订单总价
    private BigDecimal getOrderTotalPrice(List<OrderItem> orderItemList){
        BigDecimal payment = new BigDecimal("0");
        for(OrderItem orderItem : orderItemList)
            payment = BigDecimalUtil.add(payment.doubleValue(),orderItem.getTotalPrice().doubleValue()); //每一项的总价都加进来
        return payment;
    }
    //此函数用于生成订单号
    private long generateOrderNo(){
        long currentTime = System.currentTimeMillis();
        return currentTime + new Random().nextInt(100);
    }
    //此函数用于生成订单
    private Order assembleOrder(Integer userId,Integer shippingId,BigDecimal payment){
        Order order = new Order();
        //生成订单号
        long orderNo = this.generateOrderNo();
        order.setOrderNo(orderNo);
        //支付状态，未付款
        order.setStatus(Const.OrderStatusEnum.NO_PAY.getCode());
        order.setPostage(0); //运费设置为0
        //支付方式，在线支付
        order.setPaymentType(Const.PaymentTypeEnum.ONLINE_PAY.getCode());
        order.setPayment(payment);
    
        order.setUserId(userId); //购买的用户的ID
        order.setShippingId(shippingId); //发货地址的ID
        //发货时间等等
        //付款时间等等
        //插入订单
        int rowCount = orderMapper.insert(order);
        if(rowCount > 0)
            return order;
        return null;
    } 
    //减少商品的库存
    private void reduceProductStock(List<OrderItem> orderItemList){
        for(OrderItem orderItem : orderItemList){
            Product product = productMapper.selectByPrimaryKey(orderItem.getProductId());
            product.setStock(product.getStock()-orderItem.getQuantity());
            productMapper.updateByPrimaryKeySelective(product);
        }
    }
    //清空购物车
    private void cleanCart(List<Cart> cartList){
        for(Cart cart : cartList)
            cartMapper.deleteByPrimaryKey(cart.getId());
    }
    //将订单包装一下
    private OrderVo assembleOrderVo(Order order,List<OrderItem> orderItemList){   //order:订单,orderItemList:订单明细
        OrderVo orderVo = new OrderVo();
        orderVo.setOrderNo(order.getOrderNo());
        orderVo.setPayment(order.getPayment());
        orderVo.setPaymentType(order.getPaymentType());
        orderVo.setPaymentTypeDesc(Const.PaymentTypeEnum.codeOf(order.getPaymentType()).getValue());
        orderVo.setPostage(order.getPostage());
        orderVo.setStatus(order.getStatus());
        orderVo.setStatusDesc(Const.OrderStatusEnum.codeOf(order.getStatus()).getValue());
    
        orderVo.setShippingId(order.getShippingId());
        Shipping shipping = shippingMapper.selectByPrimaryKey(order.getShippingId());
        if(shipping != null){
            orderVo.setReceiverName(shipping.getReceiverName());
            orderVo.setShippingVo(assembleShippingVo(shipping));
        }
    
        orderVo.setPaymentTime(DateTimeUtil.dateToStr(order.getPaymentTime()));
        orderVo.setSendTime(DateTimeUtil.dateToStr(order.getSendTime()));
        orderVo.setEndTime(DateTimeUtil.dateToStr(order.getEndTime()));
        orderVo.setCreateTime(DateTimeUtil.dateToStr(order.getCreateTime()));
        orderVo.setCloseTime(DateTimeUtil.dateToStr(order.getCloseTime()));
        orderVo.setImageHost(PropertiesUtil.getProperty("ftp.server.http.prefix"));
    
        List<OrderItemVo> orderItemVoList = Lists.newArrayList();
    
        for(OrderItem orderItem : orderItemList){
            OrderItemVo orderItemVo = assembleOrderItemVo(orderItem);
            orderItemVoList.add(orderItemVo);
        }
        orderVo.setOrderItemVoList(orderItemVoList); //订单的明细
        return orderVo;
    }
    //封装收货地址
    private ShippingVo assembleShippingVo(Shipping shipping){
        ShippingVo shippingVo = new ShippingVo();
        shippingVo.setReceiverName(shipping.getReceiverName());
        shippingVo.setReceiverAddress(shipping.getReceiverAddress());
        shippingVo.setReceiverProvince(shipping.getReceiverProvince());
        shippingVo.setReceiverCity(shipping.getReceiverCity());
        shippingVo.setReceiverDistrict(shipping.getReceiverDistrict());
        shippingVo.setReceiverMobile(shipping.getReceiverMobile());
        shippingVo.setReceiverZip(shipping.getReceiverZip());
        shippingVo.setReceiverPhone(shippingVo.getReceiverPhone());
        return shippingVo;
    }

Mapper.xml：

<select id="selectCheckedCartByUserId" parameterType="int" resultMap="BaseResultMap">
        SELECT
        <include refid="Base_Column_List"/>
        from mmall_cart
        where user_id = #{userId}
        and checked = 1
    </select>
    
    
    <insert id="batchInsert" parameterType="list">
      insert into mmall_order_item (id, order_no,user_id, product_id,
      product_name, product_image, current_unit_price,
      quantity, total_price, create_time,
      update_time)
      values
      <foreach collection="orderItemList" index="index" item="item" separator=",">
      (
        #{item.id},#{item.orderNo},#{item.userId},#{item.productId},#{item.productName},#{item.productImage},#{item.currentUnitPrice},#{item.quantity},#{item.totalPrice},now(),now()
      )
      </foreach>
    </insert>

**强大的常量、枚举设计**  
用接口定义常量最大的好处是有一个group的概念，很简单，我们相关的常量放在一个interface里，以后维护的成本会低很多。例如课程里的一些具有组概念的，就放在一个interface里，而相对独立的常量就用类常量。  
枚举的话，key-value，有状态码，还有对应的中文说明，例如我们的订单状态。

public class Const {
        public enum OrderStatusEnum{
            CANCELED(0,"已取消"),
            NO_PAY(10,"未支付"),
            PAID(20,"已付款"),
            SHIPPED(40,"已发货"),
            ORDER_SUCCESS(50,"订单完成"),
            ORDER_CLOSE(60,"订单关闭");
    
            OrderStatusEnum(int code,String value){
                this.code = code;
                this.value = value;
            }
            private String value;
            private int code;
    
            public String getValue() {
                return value;
            }
    
            public int getCode() {
                return code;
            }
    
            public static OrderStatusEnum codeOf(int code){
                for(OrderStatusEnum orderStatusEnum : values()){
                    if(orderStatusEnum.getCode() == code){
                        return orderStatusEnum;
                    }
                }
                throw new RuntimeException("么有找到对应的枚举");
            }
        }
    }

**订单号生成规则**  
1.订单号无重复性；  
2.如果方便客服的话，最好是“日期+自增数”样式的订单号，客服一看便知道订单是否在退货保障期限内容；  
3.订单号长度尽量保持短（10位以内），方便用户，尤其电话投诉时，长的号码报错几率高，影响客服效率；

//此函数用于生成订单号
    private long generateOrderNo(){
        long currentTime = System.currentTimeMillis();
        return currentTime + new Random().nextInt(100);
    }

--------------------

**Java面试的完整博客目录如下：[Java笔试面试目录][Java]**

> **转载请标明出处，原文地址：[https://blog.csdn.net/weixin\_41835916][https_blog.csdn.net_weixin_41835916] 如果觉得本文对您有帮助，请点击顶支持一下，您的支持是我写作最大的动力，谢谢。  
> ![这里写图片描述][70]**

[Java]: https://blog.csdn.net/weixin_41835916/article/details/81413498
[https_blog.csdn.net_weixin_41835916]: https://blog.csdn.net/weixin_41835916
[70]: /images/20210923/9794239cdfb5484f9c2546cbf5fbcc07.png