JavaOOP如何用接口实现松耦合

public interface Payment {
    void process(double amount);
}

public class Alipay implements Payment {
    public void process(double amount) {
        System.out.println("使用支付宝支付: " + amount);
    }
}

public class BankPayment implements Payment {
    public void process(double amount) {
        System.out.println("使用银行卡支付: " + amount);
    }
}

public class Order {
    private Payment payment;

    public Order(Payment payment) {
        this.payment = payment;
    }

    public void checkout(double amount) {
        payment.process(amount);
    }
}

Order order1 = new Order(new Alipay());
order1.checkout(99.9);

Order order2 = new Order(new BankPayment());
order2.checkout(150.0);

public class PaymentFactory {
    public static Payment getPayment(String type) {
        return switch (type) {
            case "alipay" -> new Alipay();
            case "bank"   -> new BankPayment();
            default       -> throw new IllegalArgumentException("不支持的支付方式");
        };
    }
}