spring boot实现加入购物车的代码

以下是一个简单的Spring Boot实现加入购物车的代码示例：

1. Cart实体类

@Entity
@Table(name = "cart")
public class Cart {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "product_id", nullable = false)
    private Product product;

    private int quantity;

    private double price;

    // getters and setters
}

2. Product实体类

@Entity
@Table(name = "product")
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    private String description;

    private double price;

    // getters and setters
}

3. CartRepository接口

@Repository
public interface CartRepository extends JpaRepository<Cart, Long> {
}

4. CartService类

@Service
public class CartService {
    @Autowired
    private CartRepository cartRepository;

    public void addToCart(Product product, int quantity) {
        Cart cart = new Cart();
        cart.setProduct(product);
        cart.setQuantity(quantity);
        cart.setPrice(product.getPrice() * quantity);
        cartRepository.save(cart);
    }

    public void removeFromCart(Long cartId) {
        cartRepository.deleteById(cartId);
    }

    public void updateCart(Long cartId, int quantity) {
        Cart cart = cartRepository.findById(cartId).orElse(null);
        if (cart != null) {
            cart.setQuantity(quantity);
            cart.setPrice(cart.getProduct().getPrice() * quantity);
            cartRepository.save(cart);
        }
    }

    public List<Cart> getCartItems() {
        return cartRepository.findAll();
    }

    public double getTotalPrice() {
        List<Cart> cartItems = cartRepository.findAll();
        double totalPrice = 0.0;
        for (Cart cart : cartItems) {
            totalPrice += cart.getPrice();
        }
        return totalPrice;
    }
}

5. CartController类

@RestController
@RequestMapping("/cart")
public class CartController {
    @Autowired
    private CartService cartService;

    @PostMapping("/add")
    public void addToCart(@RequestParam Long productId, @RequestParam int quantity) {
        Product product = productService.getProductById(productId);
        cartService.addToCart(product, quantity);
    }

    @DeleteMapping("/{cartId}")
    public void removeFromCart(@PathVariable Long cartId) {
        cartService.removeFromCart(cartId);
    }

    @PutMapping("/{cartId}")
    public void updateCart(@PathVariable Long cartId, @RequestParam int quantity) {
        cartService.updateCart(cartId, quantity);
    }

    @GetMapping("/")
    public List<Cart> getCartItems() {
        return cartService.getCartItems();
    }

    @GetMapping("/total-price")
    public double getTotalPrice() {
        return cartService.getTotalPrice();
    }
}

在以上代码中，我们使用了Spring Data JPA来实现数据访问，并使用了RESTful API来实现加入购物车、查看购物车、删除购物车等操作。此外，我们还使用了@Autowired注解来自动装配CartService和ProductService类。