使用泛型参数创建实例

Question

[编辑]

我再次整理我的问题，

参数模型

public class PaymentModel
{   
    ... 
}

public class CCPaymentModel : PaymentModel
{
    ...
}

public class PaypalPaymentModel : PaymentModel
{
    ...
}

public class GooglePaymentModel : PaymentModel
{
    ...
}    

接口类

public interface IPayment<T> where T : PaymentModel
{
    ...
}

模型（从 IPayment 继承），

public class SagePayment
    : IPayment<CreditCardPaymentInfo>
{
    public void MakePayment( CreditCardPaymentInfo creditCardPaymentInfo ) {
        // ...
    }

    public void MakeRefund( CreditCardPaymentInfo creditCardPaymentInfo ) {
        // ...
    }
}

public class GooglePayment
    : IPayment<GooglePaymentModel>
{
    public void MakePayment( GooglePaymentModel paymentInfo ) {
        // ...
    }

    public void MakeRefund( GooglePaymentModel paymentInfo ) {
        // ...
    }
}

public class PaypalPayment
    : IPayment<PayPalPaymentModel>
{...}

控制器（创建实例）

IPayment<???> paymentProcess; // //Error    1   Using the generic type 'com.WebUI.Models.IPayment<T>' requires 1 type arguments

if (Regex.IsMatch(paytype, "^Credit Card"))
{
    paymentProcess = new SagePayment(); // it need CCPaymentModel type parameter
}
else if (Regex.IsMatch(paytype, "^PayPal"))
{
    paymentProcess = new PayPalPayment(); // it need PaypalPaymentModel type parameter
}
else if (Regex.IsMatch(paytype, "^Google"))
{
    paymentProcess = new GooglePayment(); // it need GooglePaymentModel type parameter
}

[EDIT]

public void Charge(string paytype,orderNo){

    IPayment<???> paymentProcess; // //Error    1   Using the generic type 'com.WebUI.Models.IPayment<T>' requires 1 type arguments
    Object payinfo;

    if (Regex.IsMatch(paytype, "^Credit Card"))
    {
        paymentProcess = new SagePayment(); // <== Error, Can not casting
        payinfo = getPaymentInfo(paytype, orderNo); // it return CCPaymentModel type object
    }
    else if (Regex.IsMatch(paytype, "^PayPal"))
    {
        paymentProcess = new PayPalPayment();
        payinfo = getPaymentInfo(paytype, orderNo); // it return PaypalPaymentModel type object
    }
    else if (Regex.IsMatch(paytype, "^Google"))
    {
        paymentProcess = new GooglePayment(); // it return GooglePaymentModel type object
        payinfo = getPaymentInfo(paytype, orderNo); 
    }

    paymentProcess.MakePayment(payinfo);
}

[编辑#2]

有了这个，

public interface IPayment {
}

public interface IPayment<T> : IPayment where T : PaymentModel
{
    void MakePayment(string pickno);
    void makeRefund(T refundInfo);
}

我收到一个错误，错误 1“com.WebUI.Models.IPayment”不包含“MakePayment”的定义，并且没有扩展方法“MakePayment”接受“Ecom.WebUI.Models.IPayment”类型的第一个参数可以找到（您是否缺少 using 指令或程序集引用？）

所以，为了避免这个错误，我将 MakePayment 方法移动到上层接口类，

public interface IPayment {
    void MakePayment(string pickno);
}

public interface IPayment<T> : IPayment where T : PaymentModel
{
    void makeRefund(T refundInfo);
}

现在，错误消失了，但是在 makeRefund 的情况下我应该怎么做呢？ 因为需要泛型类型参数，所以无法转到上层接口类。

你能帮我多一点吗？

Answer 1

您可能希望有另一个 IPayment 接口，而没有 IPayment 继承自的泛型。那就是：

public interface IPayment
{

}

public interface IPayment<T> : IPayment where T : PaymentModel
{

}

编辑：如果您真的不想拥有IPayment 基本接口，那么您必须将它们视为object 类型：

object paymentProcess;

if (Regex.IsMatch(paytype, "^Credit Card"))
{
    paymentProcess = new SagePayment();
}
else if (Regex.IsMatch(paytype, "^PayPal"))
{
    paymentProcess = new PayPalPayment();
}
else if (Regex.IsMatch(paytype, "^Google"))
{
    paymentProcess = new GooglePayment();
}

但这可能会在以后花费您；无论您将不得不强制转换以使用特定的实现类型。你真的最好使用基本接口。你甚至可以很好地使用它：

public interface IPayment
{
    PaymentModel Payment { get; }
}

因此，您可以参考和使用PaymentModel，而无需知道它实际上是一个GooglePaymentModel。

编辑：根据您的评论，您可能有以下内容：

public interface IPayment
{
    void MakePayment(string pickno);
}

public interface IPayment<T> : IPayment where T : PaymentModel
{
    void MakeRefund(T refundInfo);
}

您甚至可以针对PaymentModel 键入非通用MakeRefund 版本，因此您的调用代码可能不在乎它是否为GooglePayment。 （但如果他们通过PayPalPayment 可能会导致其他问题，这取决于您）

编辑：根据你的最新代码，你会想要这样的东西：

public interface IPayment
{

}

public interface IPayment<T> : IPayment where T : PaymentModel
{
    void MakePayment(T paymentInfo);
    void MakeRefund(T paymentInfo);
}

您的控制器/工厂如下所示：

//not sure on the exact signature since you didn't provide it
public IPayment CreatePayment(string paytype)
{
    IPayment paymentProcess = null;

    if (Regex.IsMatch(paytype, "^Credit Card"))
    {
        paymentProcess = new SagePayment();
    }
    else if (Regex.IsMatch(paytype, "^PayPal"))
    {
        paymentProcess = new PayPalPayment();
    }
    else if (Regex.IsMatch(paytype, "^Google"))
    {
        paymentProcess = new GooglePayment();
    }

    return paymentProcess
}

您的使用代码某处必须将其转换为已知的支付类型才能使用：

IPayment untypedPayment = Factory.CreatePayment("PayPal");
IPayment<PayPalPaymentModel> typedPayment = (IPayment<PayPalPaymentModel>)untypedPayment;
typedPayment.MakePayment(new PayPalPaymentModel());

//or alternatively
IPayment untypedPayment = Factory.CreatePayment("PayPal");  
PayPalPayment typedPayment = (PayPalPayment)untypedPayment;
typedPayment.MakeRefund(new PayPalPaymentModel());

编辑：根据您的最新编辑，这就是您想要的。针对 PaymentModel 驱动您的基本 IPayment 调用。然后在特定的实现中，您可以在运行时进行强制转换或类型检查：

public interface IPayment
{
    void MakePayment(PaymentModel paymentInfo);
    void MakeRefund(PaymentModel paymentInfo);
}

public interface IPayment<T> : IPayment where T : PaymentModel
{

}

public class GooglePayment
    : IPayment<GooglePaymentModel>
{
    public void MakePayment(PaymentModel paymentInfo) {
    GooglePaymentModel googlePayment = (GooglePaymentModel)paymentInfo;
    // ...
    }

    public void MakeRefund(PaymentModel paymentInfo) {
    GooglePaymentModel googlePayment = (GooglePaymentModel)paymentInfo;
    // ...
    }
}

然后你的Controller:

public void Charge(string paytype,orderNo){

    IPayment paymentProcess = null;
    PaymentModel payinfo = null;

    if (Regex.IsMatch(paytype, "^Credit Card"))
    {
        paymentProcess = new SagePayment();
        payinfo = getPaymentInfo(paytype, orderNo);
    }
    else if (Regex.IsMatch(paytype, "^PayPal"))
    {
        paymentProcess = new PayPalPayment();
        payinfo = getPaymentInfo(paytype, orderNo);
    }
    else if (Regex.IsMatch(paytype, "^Google"))
    {
        paymentProcess = new GooglePayment();
        payinfo = getPaymentInfo(paytype, orderNo); 
    }

    paymentProcess.MakePayment(payinfo);
}

public PaymentModel getPaymentInfo(string paytype,orderNo)
{
    //return some payment model
}