如何在 C# .Net 核心的工厂设计模式中使用反射答案

【问题标题】：How to use Reflection in factory design patterns in C# .Net core如何在 C# .Net 核心的工厂设计模式中使用反射
【发布时间】：2020-01-04 07:55:59
【问题描述】：

我已经通过以下方式在 c# .Net 核心中实现了工厂方法。我有几个具体的产品，比如说 Gateway1 和 Gateway2

public interface IGateway
{
    void Test();
}

ConcreteCreator：

public class PaymentFactory
{
    private readonly IPaymentTransactionRepository _paymentTransactionRepository;
    private readonly IPaymentGatewayRepository _paymentGatewayRepository;

    public PaymentFactory(IPaymentTransactionRepository paymentTransactionRepository,
        IPaymentGatewayRepository paymentGatewayRepository)
    {
        _paymentTransactionRepository = paymentTransactionRepository;
        _paymentGatewayRepository = paymentGatewayRepository;
    }

    public IGateway ExecuteCreation(string bank)
    {
        switch (bank)
        {
            case "Gateway1":
                {
                    return new Gateway1(_paymentGatewayRepository);
                }
            case "Gateway2":
                {
                    return new Gateway2(_paymentTransactionRepository, _paymentGatewayRepository);

                }
            default:
                {
                    return null;

                }
        }
    }

}

混凝土产品：

public class Gateway1 : IGateway
{
    private readonly IPaymentTransactionRepository _paymentTransactionRepository;

    public Gateway1(IPaymentTransactionRepository paymentGatewayRepository)
    {
        _paymentGatewayRepository = paymentGatewayRepository;
    }

    public void Test()
    {
        //code
    }
}

public class Gateway2 : IGateway
{
    private readonly IPaymentTransactionRepository _paymentTransactionRepository;
    private readonly IPaymentGatewayRepository _paymentGatewayRepository;

    public Gateway2(IPaymentTransactionRepository paymentGatewayRepository,
        IPaymentGatewayRepository paymentGatewayRepository)
    {
        _paymentGatewayRepository = paymentGatewayRepository;
        _paymentGatewayRepository = paymentGatewayRepository;
    }

    public void Test()
    {
        //code
    }
}

此代码正在运行，但我想对其进行两处更改。

1- 如何通过反射实现工厂方法？

2- CreateConcreteProducts如何传入多个参数？

提前致谢。

【问题讨论】：

标签： c# .net design-patterns reflection .net-core

【解决方案1】：

您可以使用下面的代码。您需要更改PaymentFactory，如下所示。您可以用户 IServiceProvider 将服务注入到使用它的类的构造函数中。

具体产品名称：

public enum PaymentGatewayEnum
{
    Gateway1 = 1,
    Gateway2 = 2,
}

然后 PaymentFactory：

public class PaymentFactory
{
    private readonly IServiceProvider _serviceProvider;
    public PaymentFactory(IServiceProvider serviceProvider)
    {
        _serviceProvider = serviceProvider;
    }

    public IGateway ExecuteCreation(PaymentGatewayEnum bank)
    {
        var services = AppDomain.CurrentDomain.GetAssemblies().SelectMany(x => x.GetTypes())
            .Where(x => typeof(IGateway).IsAssignableFrom(x) && !x.IsInterface && !x.IsAbstract)
            .FirstOrDefault(x => string.Equals(x.Name, bank.ToString(), StringComparison.CurrentCultureIgnoreCase));

        return Activator.CreateInstance(services, _serviceProvider) as IGateway;
    }

}

然后：

public class Gateway1 : IGateway
{
    private readonly IPaymentTransactionRepository _paymentTransactionRepository;

    public Gateway1(IServiceProvider serviceProvider)
    {
        _paymentTransactionRepository = (IPaymentTransactionRepository)serviceProvider.GetService(typeof(IPaymentTransactionRepository));
    }

    public void Test()
    {
        //code
    }
}

public class Gateway2 : IGateway
{
    private readonly IPaymentTransactionRepository _paymentTransactionRepository;
    private readonly IPaymentGatewayRepository _paymentGatewayRepository;

    public Gateway2(IServiceProvider serviceProvider)
    {
        _paymentTransactionRepository = (IPaymentTransactionRepository)serviceProvider.GetService(typeof(IPaymentTransactionRepository));
        _paymentGatewayRepository = (IPaymentGatewayRepository)serviceProvider.GetService(typeof(IPaymentGatewayRepository));
    }

    public void Test()
    {
        //code
    }
}

【讨论】：