在Java中如何使用接口实现策略模式_OOP策略模式操作技巧

public interface PaymentStrategy {
    void pay(double amount);
}

public class CreditCardPayment implements PaymentStrategy {
    public void pay(double amount) {
        System.out.println("使用信用卡支付: " + amount + "元");
    }
}

public class AlipayPayment implements PaymentStrategy {
    public void pay(double amount) {
        System.out.println("使用支付宝支付: " + amount + "元");
    }
}

public class ShoppingCart {
    private PaymentStrategy paymentStrategy;

    public ShoppingCart(PaymentStrategy strategy) {
        this.paymentStrategy = strategy;
    }

    public void setPaymentStrategy(PaymentStrategy strategy) {
        this.paymentStrategy = strategy;
    }

    public void checkout(double amount) {
        paymentStrategy.pay(amount);
    }
}

public class Client {
    public static void main(String[] args) {
        ShoppingCart cart = new ShoppingCart(new CreditCardPayment());
        cart.checkout(299.9);

        // 切换为支付宝支付
        cart.setPaymentStrategy(new AlipayPayment());
        cart.checkout(150.0);
    }
}

使用信用卡支付: 299.9元
使用支付宝支付: 150.0元