java使用策略模式实现支付功能

在Java中使用策略模式实现支付功能，可以按照以下步骤进行：

定义支付策略接口（PaymentStrategy），包含一个支付方法（pay）。

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

创建具体的支付策略实现类，实现支付策略接口。

public class CreditCardPayment implements PaymentStrategy {
    private String cardNumber;
    private String expiryDate;
    private String cvv;

    public CreditCardPayment(String cardNumber, String expiryDate, String cvv) {
        this.cardNumber = cardNumber;
        this.expiryDate = expiryDate;
        this.cvv = cvv;
    }

    @Override
    public void pay(double amount) {
        System.out.println("Paid " + amount + " using credit card.");
    }
}

public class PayPalPayment implements PaymentStrategy {
    private String email;
    private String password;

    public PayPalPayment(String email, String password) {
        this.email = email;
        this.password = password;
    }

    @Override
    public void pay(double amount) {
        System.out.println("Paid " + amount + " using PayPal.");
    }
}

创建一个支付上下文（PaymentContext）类，用于设置和获取支付策略。

public class PaymentContext {
    private PaymentStrategy paymentStrategy;

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

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

在客户端代码中使用策略模式进行支付。

public class Main {
    public static void main(String[] args) {
        PaymentContext paymentContext = new PaymentContext();

        // 使用信用卡支付
        PaymentStrategy creditCardPayment = new CreditCardPayment("1234567890", "12/23", "123");
        paymentContext.setPaymentStrategy(creditCardPayment);
        paymentContext.pay(100.0);

        // 使用PayPal支付
        PaymentStrategy payPalPayment = new PayPalPayment("example@example.com", "password");
        paymentContext.setPaymentStrategy(payPalPayment);
        paymentContext.pay(200.0);
    }
}

通过使用策略模式，可以实现支付功能的灵活扩展，可以轻松添加新的支付策略实现类，并且在运行时可以动态地切换支付策略