JavaWeb后台购物车类实现代码详解

package com.wxd.shopping;

public class Item {
  private int id; //商品id
  private String name;//商品名称
  private String city;//商品产地
  private double price;//商品价格
  private int number;//商品数量
  private String picture;//商品图片地址

  public int getId() {
    return id;
  }

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

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public String getCity() {
    return city;
  }

  public void setCity(String city) {
    this.city = city;
  }

  public double getPrice() {
    return price;
  }

  public void setPrice(double price) {
    this.price = price;
  }

  public int getNumber() {
    return number;
  }

  public void setNumber(int number) {
    this.number = number;
  }

  public String getPicture() {
    return picture;
  }

  public void setPicture(String picture) {
    this.picture = picture;
  }

  /**
   * 重写hashCode方法，使得在购物车添加商品的时候，如果id和名称相同就判定为同一件商品
   * @return
   */
  @Override
  public int hashCode() {
    return (this.getId()+this.getName()).hashCode();
  }

  /**
   * 重写equals方法，判断是否为同一个对象
   * @param obj
   * @return
   */
  @Override
  public boolean equals(Object obj) {
    if(this==obj){
      return true;
    }
    if(obj instanceof Item){
      Item i= (Item) obj;
      if(this.getId()==i.getId()&&this.getName().equals(i.getName())){
        return true;
      }else{
        return false;
      }
    }else{
      return false;
    }
  }

  @Override
  public String toString() {
    return "Item{" +
        "id=" + id +
        ", name='" + name + '\'' +
        ", city='" + city + '\'' +
        ", price=" + price +
        ", number=" + number +
        ", picture='" + picture + '\'' +
        '}';
  }

  //有参构造
  public Item(int id, String name, String city, double price, int number, String picture) {
    this.id = id;
    this.name = name;
    this.city = city;
    this.price = price;
    this.number = number;
    this.picture = picture;
  }
  //无参构造
  public Item() {
  }
}

package com.wxd.shopping;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

//购物车
public class Cart {
  //购买商品的集合
  private HashMap<Item,Integer> goods;
  //购物车的总金额
  private double totalPrice;

  //构造方法初始化数据
  public Cart(){
    goods=new HashMap<Item,Integer>();
    totalPrice=0.0;
  }
  public HashMap<Item, Integer> getGoods() {
    return goods;
  }

  public void setGoods(HashMap<Item, Integer> goods) {
    this.goods = goods;
  }

  public double getTotalPrice() {
    return totalPrice;
  }

  public void setTotalPrice(double totalPrice) {
    this.totalPrice = totalPrice;
  }
  //添加商品进购物车的方法
  public boolean addGoodsInCart(Item item,int number){
    if(goods.containsKey(item)){
      goods.put(item,goods.get(item)+number);
    }else{
      goods.put(item,number);
    }
    calTotalPrice();//重新计算购物车的总金额
    return true;
  }
  //删除商品的方法
  public boolean removeGoodsFromCart(Item item){
    goods.remove(item);
    calTotalPrice();//重新计算购物车的总金额
    return true;
  }
  //统计购物车的总金额
  public double calTotalPrice(){
    double sum=0.0;
    Set<Item> keys=goods.keySet();
    Iterator<Item> iterator = keys.iterator();
    while (iterator.hasNext()){
      Item i = iterator.next();
      sum+=i.getPrice()*goods.get(i);
    }
    this.setTotalPrice(sum);//设置购物车的总金额
    return this.getTotalPrice();
  }

  //测试的main方法
  public static void main(String[] args) {
    //先创建两个商品对象
    Item i1=new Item(1,"耐克","温州",300.0,500,"001.jpg");
    Item i2=new Item(2,"阿迪","广州",500.0,500,"001.jpg");
    Item i3=new Item(1,"耐克","温州",300.0,500,"001.jpg");
    Cart c=new Cart();
    c.addGoodsInCart(i1,1);
    c.addGoodsInCart(i2,2);
    //再次购买耐克鞋
    c.addGoodsInCart(i3,3);
    //遍历购买商品的集合
    HashMap<Item, Integer> goods = c.getGoods();
    Set<Map.Entry<Item, Integer>> entries = goods.entrySet();
    for(Map.Entry<Item, Integer> itemEntry:entries){
      System.out.println(itemEntry.toString());
    }
    System.out.println("购物车总金额:"+c.getTotalPrice());
  }
}