泛型C＃ - 从静态泛型类创建实例

Question

我的应用程序中有一个工厂类，但由于我对泛型缺乏了解，我不知道如何创建这种特殊类型的实例。

有人会友好地指出我如何调用这个类，以便它返回一个服务...任何帮助将不胜感激。

public class ServiceFactory<TService> where TService : WebServicesClientProtocol, new()
{

    public static TService GetSecureService(string serviceUrl, X509Certificate certificate)
    {
        if (serviceUrl == null)
        {
            throw new ArgumentNullException(nameof(serviceUrl), "Service URL must be specified.");
        }

        if (serviceUrl == string.Empty)
        {
            throw new ArgumentException("Service URL cannot be empty.", nameof(serviceUrl));
        }

        if (certificate == null)
        {
            throw new ArgumentNullException(nameof(certificate), "Client certificate must be specified.");
        }

        return Service(serviceUrl, certificate);
    }

    private static TService Service(string serviceUrl, X509Certificate certificate)
    {
        return ConfigureService((TService)Activator.CreateInstance(typeof(TService)), serviceUrl, certificate);
    }

    public static TService ConfigureService(TService service, string serviceUrl, X509Certificate certificate)
    {
        service.PreAuthenticate = true;
        service.Credentials = CredentialCache.DefaultCredentials;
        service.Timeout = 250;
        service.Url = serviceUrl;

        return ConfigureRequestSignature(service, certificate);
    }

    private static TService ConfigureRequestSignature(TService service, X509Certificate certificate)
    {
        X509SecurityToken signatureToken = new X509SecurityToken(certificate);
        MessageSignature signature = new MessageSignature(signatureToken);

        signature.SignatureOptions = SignatureOptions.IncludeTimestamp | SignatureOptions.IncludeSoapBody | SignatureOptions.IncludeMessageId | SignatureOptions.IncludeAction;

        SoapContext requestContext = service.RequestSoapContext;
        requestContext.Security.Tokens.Add(signatureToken);
        requestContext.Security.Elements.Add(signature);

        // TTL must be less than 60 seconds, otherwise the request will be discarded.
        requestContext.Security.Timestamp.TtlInSeconds = 50;

        return service;
    }
}

Answer 1

在不知道可以实例化的类的名称的情况下......

var service = ServiceFactory<ConcreteImplementationService>.GetSecureService(url, cert);

Answer 2

由于您使用的是静态方法，因此请使用方法级通用参数：

TService GetSecureService<TService>(string serviceUrl, X509Certificate certificate)
   where TService : WebServicesClientProtocol, new()
{
...
     return Service<TService>(serviceUrl, certificate);
}

您可能会发现所有方法都将使用此模式并按照我上面调用Service（）时的方式传递泛型类型。

MSDN文章的通用方法： https ： //msdn.microsoft.com/en-us/library/twcad0zb.aspx