Java购物车功能实现教程

public class Product {
    private String id;
    private String name;
    private double price;
public Product(String id, String name, double price) {
    this.id = id;
    this.name = name;
    this.price = price;
}

// Getter方法（必须提供，用于获取属性）
public String getId() { return id; }
public String getName() { return name; }
public double getPrice() { return price; }

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (!(o instanceof Product)) return false;
    Product product = (Product) o;
    return id.equals(product.id);
}

@Override
public int hashCode() {
    return id.hashCode();
}
}

public class CartItem {
    private Product product;
    private int quantity;
public CartItem(Product product, int quantity) {
    this.product = product;
    this.quantity = quantity;
}

public Product getProduct() { return product; }
public int getQuantity() { return quantity; }
public void setQuantity(int quantity) { this.quantity = quantity; }

public double getTotalPrice() {
    return product.getPrice() * quantity;
}
}

import java.util.*;
public class ShoppingCart {
private Map items;
public ShoppingCart() {
    items = new HashMap<>();
}

// 添加商品到购物车
public void addProduct(Product product, int quantity) {
    if (quantity <= 0) {
        System.out.println("数量必须大于0");
        return;
    }
    CartItem item = items.get(product.getId());
    if (item != null) {
        item.setQuantity(item.getQuantity() + quantity);
    } else {
        items.put(product.getId(), new CartItem(product, quantity));
    }
    System.out.println(product.getName() + " 已加入购物车，数量：" + quantity);
}

// 更新商品数量
public void updateQuantity(String productId, int quantity) {
    CartItem item = items.get(productId);
    if (item != null) {
        if (quantity <= 0) {
            items.remove(productId);
            System.out.println("已从购物车移除该商品");
        } else {
            item.setQuantity(quantity);
            System.out.println("商品数量已更新");
        }
    } else {
        System.out.println("购物车中无此商品");
    }
}

// 移除商品
public void removeProduct(String productId) {
    if (items.remove(productId) != null) {
        System.out.println("商品已移除");
    } else {
        System.out.println("未找到该商品");
    }
}

// 查看购物车内容
public void viewCart() {
    if (items.isEmpty()) {
        System.out.println("购物车为空");
        return;
    }
    System.out.println("\n--- 购物车内容 ---");
    for (CartItem item : items.values()) {
        System.out.printf("%s × %d = ¥%.2f%n",
                item.getProduct().getName(),
                item.getQuantity(),
                item.getTotalPrice());
    }
    System.out.printf("总计：¥%.2f%n", getTotalPrice());
}

// 计算总金额
public double getTotalPrice() {
    return items.values().stream()
            .mapToDouble(CartItem::getTotalPrice)
            .sum();
}

// 清空购物车
public void clear() {
    items.clear();
    System.out.println("购物车已清空");
}
}

public class Main {
    public static void main(String[] args) {
        // 创建商品
        Product p1 = new Product("P001", "iPhone", 6999.0);
        Product p2 = new Product("P002", "AirPods", 1299.0);
    // 创建购物车
    ShoppingCart cart = new ShoppingCart();

    // 添加商品
    cart.addProduct(p1, 1);
    cart.addProduct(p2, 2);
    cart.addProduct(p1, 1); // 同一商品再次添加

    // 查看购物车
    cart.viewCart();

    // 修改数量
    cart.updateQuantity("P002", 1);

    // 再次查看
    cart.viewCart();
}
}