ssm actual combat (6) ------ shopping cart management

Shopping cart management

Features:

 Added goods; updating the number of items; query the number of items; removal of goods; radio / canceled; Select All / Cancel; cart list

 

interface

 

Portal: cart list list; cart add products; update cart quantity of a product; remove the cart a product; cart Select a product; deselect a product; the number of queries Shopping Cart; cart full election; cart Uncheck All

 

Note

guava interception string:

productIds = "zhangshang, lisi" // string of a plurality of user id 
List <String> productList = Splitter.on ( ",") splitToList (productIds).;

 Calculated quantity of a hidden danger: when the query to the number of empty, null can not be assigned to int. Solution: IFNULL (sum (quantity), 0) Mysql built-in function, if the sum (quantity) is empty, then assigned 0

//mapper.java
int selectCartProductCount(@Param(value = "userId") Integer userId);
//mapper.xml
  <select id="selectCartProductCount" parameterType="int" resultType="int">
    select IFNULL(sum(quantity),0) as count
    from eshop_cart
    where user_id=#{userId}
  </select>

 

 

 

learning target:

A cart module design: a method of encapsulating a core of the shopping cart; shopping cart every time after operation, invokes the method, which will be assembled and CartVo number check, and returns a CartVo

2 packages a cart core method

    / ** 
     * limitation cart, which determines whether the number of correct 
     * @param the userId 
     * @return 
     * / 
    Private CartVo getCartVoLimit (Integer the userId) { 
        CartVo cartVo new new CartVo = (); 
        // get the user's shopping cart List 
        List < the cart> cartList = cartMapper.selectCartByUserId (userId); 
        // create a CarProductVoList 
        List <CartProductVo> cartProductVoList = Lists.newArrayList (); 

        BigDecimal cartTotalPrice = new new BigDecimal ( "0"); 
        // determine whether the shopping cart is empty 
        if (CollectionUtils .isNotEmpty (cartList)) { 
            // the items fitted to Cart CarProductVo, then add to CarProductVoList 
            for (Cart CartItem: cartList) { 
                CartProductVo cartProductVo new new CartProductVo = ();
                cartProductVo.setId(cartItem.getId());
                cartProductVo.setUserId(userId);
                cartProductVo.setProductId(cartItem.getProductId());

                Product product=productMapper.selectByPrimaryKey(cartItem.getProductId());
                if(product!=null){
                    cartProductVo.setProductMainImage(product.getMainImage());
                    cartProductVo.setProductName(product.getName());
                    cartProductVo.setProductSubtitle(product.getSubtitle());
                    cartProductVo.setProductStatus(product.getStatus());
                    cartProductVo.setProductPrice(product.getPrice());
                    cartProductVo.setProductStock(product.getStock());
                    //判断库存
                    buyLimitCount = 0 int; 
                    IF (product.getStock ()> = cartItem.getQuantity ()) { 
                        // when sufficient stock 
                        buyLimitCount cartItem.getQuantity = (); 
                        cartProductVo.setLimitQuantity (Const.Cart.LIMIT_NUM_SUCCESS); 
                    } the else { 
                        buyLimitCount product.getStock = (); 
                        cartProductVo.setLimitQuantity (Const.Cart.LIMIT_NUM_FAIL); 
                        // update cart effective inventory 
                        the cart = new new cartForQuantity the cart (); 
                        cartForQuantity.setId(cartItem.getId());
                        cartForQuantity.setQuantity (buyLimitCount); 
                        cartMapper.updateByPrimaryKeySelective (cartForQuantity);
                    }
                    cartProductVo.setQuantity(buyLimitCount);
                    //计算总价
                     cartProductVo.setProductTotalPrice(BigDecimalUtil.mul(product.getPrice().doubleValue(),cartProductVo.getQuantity()));
                     cartProductVo.setProductChecked(cartItem.getChecked());
                }
                if(cartItem.getChecked()==Const.Cart.CHECKED){
                    cartTotalPrice=BigDecimalUtil.add(cartTotalPrice.doubleValue(),cartProductVo.getProductTotalPrice().doubleValue());
                }
                cartProductVoList.add(cartProductVo);
            }
        }
        cartVo.setCartTotalPrice(cartTotalPrice);
        cartVo.setCartProductVoList(cartProductVoList);
        cartVo.setAllChecked(this.getAllCheckedStatus(userId));
        cartVo.setImageHost(PropertiesUtil.getProperty("ftp.server.http.prefix"));
        return cartVo;
    }

    /**
     * 判断购物车是否全选
     * @param userId
     * @return
     */
    private boolean getAllCheckedStatus(Integer userId){
        if(userId==null){
            return false;
        }
        return cartMapper.selectCartProductCheckedStatusByUserId(userId)==0;
    }

 cartProductVo：

com.eshop.vo Package Penalty for; 

Import java.math.BigDecimal; 

/ ** 
 An abstract objects * combines product and cart 
 * / 
public class CartProductVo { 
    Private Integer the above mentioned id; // cart the above mentioned id 
    Private Integer userId; 
    Private productId Integer; 
    Private Integer the quantity; // number of products purchased 
    Private String productName; 
    Private String productSubtitle; 
    Private String productMainImage; 
    Private BigDecimal productPrice; 
    Private Integer productStatus; 
    Private BigDecimal productTotalPrice; // product total 
    private Integer productStock; // number of products inventory 
    Integer productChecked Private; 

    Private String limitQuantity; // limit the number of items returned results

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public Integer getProductId() {
        return productId;
    }

    public void setProductId(Integer productId) {
        this.productId = productId;
    }

    public Integer getQuantity() {
        return quantity;
    }

    public void setQuantity(Integer quantity) {
        this.quantity = quantity;
    }

    public String getProductName() {
        return productName;
    }

    public void setProductName(String productName) {
        this.productName = productName;
    }

    public String getProductSubtitle() {
        return productSubtitle;
    }

    public void setProductSubtitle(String productSubtitle) {
        this.productSubtitle = productSubtitle;
    }

    public String getProductMainImage() {
        return productMainImage;
    }

    public void setProductMainImage(String productMainImage) {
        this.productMainImage = productMainImage;
    }

    public BigDecimal getProductPrice() {
        return productPrice;
    }

    public void setProductPrice(BigDecimal productPrice) {
        this.productPrice = productPrice;
    }

    public Integer getProductStatus() {
        return productStatus;
    }

    public void setProductStatus(Integer productStatus) {
        this.productStatus = productStatus;
    }

    public BigDecimal getProductTotalPrice() {
        return productTotalPrice;
    }

    public void setProductTotalPrice(BigDecimal productTotalPrice) {
        this.productTotalPrice = productTotalPrice;
    }

    public Integer getProductStock() {
        return productStock;
    }

    public void setProductStock(Integer productStock) {
        this.productStock = productStock;
    }

    public Integer getProductChecked() {
        return productChecked;
    }

    public void setProductChecked(Integer productChecked) {
        this.productChecked = productChecked;
    }

    public String getLimitQuantity() {
        return limitQuantity;
    }

    public void setLimitQuantity(String limitQuantity) {
        this.limitQuantity = limitQuantity;
    }
}

 CartVo：

package com.eshop.vo;

import java.math.BigDecimal;
import java.util.List;

public class CartVo {
    private List<CartProductVo> cartProductVoList;
    private BigDecimal cartTotalPrice;
    private Boolean allChecked;
    private String imageHost;

    public List<CartProductVo> getCartProductVoList() {
        return cartProductVoList;
    }

    public void setCartProductVoList(List<CartProductVo> cartProductVoList) {
        this.cartProductVoList = cartProductVoList;
    }

    public BigDecimal getCartTotalPrice() {
        return cartTotalPrice;
    }

    public void setCartTotalPrice(BigDecimal cartTotalPrice) {
        this.cartTotalPrice = cartTotalPrice;
    }

    public Boolean getAllChecked() {
        return allChecked;
    }

    public void setAllChecked(Boolean allChecked) {
        this.allChecked = allChecked;
    }

    public String getImageHost() {
        return imageHost;
    }

    public void setImageHost(String imageHost) {
        this.imageHost = imageHost;
    }
}

 

3 to solve business calculation precision floating-point loss: Use BigDecimal, attention must use the constructor BigDecimal (String str) string

 

    public static BigDecimal add(double v1,double v2){
        BigDecimal b1=new BigDecimal(Double.toString(v1));
        BigDecimal b2=new BigDecimal(Double.toString(v2));
        return b1.add(b2);
    }

 

this method:

package com.eshop.util;

import java.math.BigDecimal;
import java.math.RoundingMode;

public class BigDecimalUtil {
    private BigDecimalUtil(){
        //私有构造器防止被实例化
    }
    public static BigDecimal add(double v1,double v2){
        BigDecimal b1=new BigDecimal(Double.toString(v1));
        BigDecimal b2=new BigDecimal(Double.toString(v2));
        return b1.add(b2);
    }
    public static BigDecimal sub(double v1,double v2){
        BigDecimal b1=new BigDecimal(Double.toString(v1));
        BigDecimal b2=new BigDecimal(Double.toString(v2));
        return b1.subtract(b2);
    }
    public static BigDecimal mul(double v1,double v2){
        BigDecimal b1=new BigDecimal(Double.toString(v1));
        BigDecimal b2=new BigDecimal(Double.toString(v2));
        return b1.multiply(b2);
    }
    public static BigDecimal div(double v1,double v2){
        BigDecimal b1=new BigDecimal(Double.toString(v1));
        BigDecimal b2=new BigDecimal(Double.toString(v2));
        return b1.divide(b2,2, RoundingMode.HALF_UP);
        //除不尽的情况：取两位小数，四舍五入
    }
}