如何在Golang中实现购物车功能

type Product struct {
    ID    int
    Name  string
    Price float64
}
<p>type CartItem struct {
ProductID int
Quantity  int
}</p><p>type Cart struct {
UserID int
Items  map[int]*CartItem // key: ProductID
}</p>

func (c *Cart) AddProduct(productID int, quantity int) {
    if item, exists := c.Items[productID]; exists {
        item.Quantity += quantity
    } else {
        c.Items[productID] = &CartItem{ProductID: productID, Quantity: quantity}
    }
}

func (c *Cart) RemoveProduct(productID int) {
    delete(c.Items, productID)
}

func (c *Cart) Total(products map[int]Product) float64 {
    var total float64
    for _, item := range c.Items {
        if p, ok := products[item.ProductID]; ok {
            total += p.Price * float64(item.Quantity)
        }
    }
    return total
}

var carts = make(map[int]*Cart) // 模拟存储，key: UserID
var products = map[int]Product{
    1: {ID: 1, Name: "iPhone", Price: 6999.0},
    2: {ID: 2, Name: "AirPods", Price: 1299.0},
}
<p>func addToCart(w http.ResponseWriter, r *http.Request) {
userID := 1 // 实际应从session或token获取
productID := 1
quantity := 2</p><pre class='brush:php;toolbar:false;'>cart, exists := carts[userID]
if !exists {
    cart = &Cart{UserID: userID, Items: make(map[int]*CartItem)}
    carts[userID] = cart
}

cart.AddProduct(productID, quantity)
w.WriteHeader(http.StatusOK)
fmt.Fprintf(w, "Added product %d to cart", productID)

var cartMutex sync.RWMutex
<p>func getCart(userID int) *Cart {
cartMutex.RLock()
defer cartMutex.RUnlock()
return carts[userID]
}</p>