注册使用开放泛型类型将多个接口实现为单例的服务

Question

有一个通用MyClass<T>实现了 2 个通用接口IMyInterface1<T>和IMyInterface2<T> 。 我想将其注册为单身人士。 因此，对于给定的T两个接口都将解析为MyClass的同一实例。

我正在尝试将其注册为开放泛型类型并转发到工厂方法：

services.AddSingleton(typeof(MyClass<>));
services.AddSingleton(typeof(IMyInterface1<>), sp => sp.GetRequiredService(typeof(MyClass<>)));
services.AddSingleton(typeof(IMyInterface2<>), sp => sp.GetRequiredService(typeof(MyClass<>)));

但是在运行时我收到异常消息“打开通用服务类型‘IMyInterface1`1[T]’需要注册一个开放的通用实现类型。 ”

当我为每个具体类型T注册我的单例时，即没有开放泛型类型，一切正常：

services.AddSingleton(typeof(MyClass<A>));
services.AddSingleton(typeof(IMyInterface1<A>), sp => sp.GetRequiredService(typeof(MyClass<A>)));
services.AddSingleton(typeof(IMyInterface2<A>), sp => sp.GetRequiredService(typeof(MyClass<A>)));
services.AddSingleton(typeof(MyClass<B>));
services.AddSingleton(typeof(IMyInterface1<B>), sp => sp.GetRequiredService(typeof(MyClass<B>)));
services.AddSingleton(typeof(IMyInterface2<B>), sp => sp.GetRequiredService(typeof(MyClass<B>)));

我知道还有另一种方法来注册具有两个接口的单例服务 - 通过提供实现实例而不是实现工厂。 但是我不能在“现实世界”中使用它，因为我的真实类也有很多依赖项，并且在注册阶段可能无法解决所有这些依赖项。

有没有办法使用开放的泛型类型来解决这个问题？

---

详细异常：

System.ArgumentException
  HResult=0x80070057
  Message=Open generic service type 'IMyInterface1`1[T]' requires registering an open generic implementation type. (Parameter 'descriptors')
  Source=Microsoft.Extensions.DependencyInjection
  StackTrace:
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteFactory.Populate()
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteFactory..ctor(IEnumerable`1 descriptors)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine..ctor(IEnumerable`1 serviceDescriptors, IServiceProviderEngineCallback callback)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CompiledServiceProviderEngine..ctor(IEnumerable`1 serviceDescriptors, IServiceProviderEngineCallback callback)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider..ctor(IEnumerable`1 serviceDescriptors, ServiceProviderOptions options)
   at Microsoft.Extensions.DependencyInjection.ServiceCollectionContainerBuilderExtensions.BuildServiceProvider(IServiceCollection services, ServiceProviderOptions options)
   at Microsoft.Extensions.DependencyInjection.ServiceCollectionContainerBuilderExtensions.BuildServiceProvider(IServiceCollection services)
   at WebApplication1.Startup.ConfigureServices(IServiceCollection services) in ...\WebApplication1\WebApplication1\Startup.cs:line 39
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.AspNetCore.Hosting.ConfigureServicesBuilder.InvokeCore(Object instance, IServiceCollection services)
   at Microsoft.AspNetCore.Hosting.ConfigureServicesBuilder.<>c__DisplayClass9_0.<Invoke>g__Startup|0(IServiceCollection serviceCollection)
   at Microsoft.AspNetCore.Hosting.ConfigureServicesBuilder.Invoke(Object instance, IServiceCollection services)
   at Microsoft.AspNetCore.Hosting.ConfigureServicesBuilder.<>c__DisplayClass8_0.<Build>b__0(IServiceCollection services)
   at Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.UseStartup(Type startupType, HostBuilderContext context, IServiceCollection services)
   at Microsoft.AspNetCore.Hosting.GenericWebHostBuilder.<>c__DisplayClass12_0.<UseStartup>b__0(HostBuilderContext context, IServiceCollection services)
   at Microsoft.Extensions.Hosting.HostBuilder.CreateServiceProvider()
   at Microsoft.Extensions.Hosting.HostBuilder.Build()
   at WebApplication1.Program.Main(String[] args) in ...\WebApplication1\WebApplication1\Program.cs:line 16

Answer 1

看起来你不能这样做 - 它不受支持。

以下问题似乎已经要求这样做：

• 开放泛型的 implementationFactory
• 通过工厂依赖注入开放泛型

如果您将接口注册上的sp => sp.GetRequiredService(typeof(MyClass<A>))替换为typeof(MyClass<A>)那么您将最终为您注册的每个接口获得一个单例实例，它不会听起来不像你想要的。

我能想到的最好的方法是将MyClass<T>变成管理其自己的底层实现的单例实例的外观。 您可以通过将 Facade 调用到带有静态字典的非泛型类（静态成员是每个泛型类型，因此这需要是非泛型类）来实现每个T检索真正的单例实例。

例子

注册您的服务：

services.AddSingleton(typeof(MyFacadeClass<>));
services.AddSingleton(typeof(IMyInterface1<>), typeof(MyFacadeClass<>));
services.AddSingleton(typeof(IMyInterface2<>), typeof(MyFacadeClass<>));

外观实现：

public class MyImplementationClass<T> : IMyInterface1<T>, IMyInterface2<T>
{
    public void Interface1Method()
    {
    }

    public void Interface2Method()
    {
    }
}

public class MyClassSingletonRegister
{
    public static Dictionary<Type, object> MyImplementationClassInstances = new Dictionary<Type, object>();
}

public class MyFacadeClass<T> : IMyInterface1<T>, IMyInterface2<T>
{
    private readonly MyImplementationClass<T> _instance;

    public MyFacadeClass()
    {
        _instance = GetInstance();
    }

    private MyImplementationClass<T> GetInstance()
    {
        if (!MyClassSingletonRegister.MyImplementationClassInstances.TryGetValue(typeof(T), out var instance))
        {
            Debug.WriteLine("Creating new instance for " + typeof(T).Name);
            var myImplementationClass = new MyImplementationClass<T>();
            MyClassSingletonRegister.MyImplementationClassInstances.Add(typeof(T), myImplementationClass);

            instance = myImplementationClass;
        }

        return (MyImplementationClass<T>) instance;
    }


    public void Interface1Method()
    {
        _instance.Interface1Method();
    }

    public void Interface2Method()
    {
        _instance.Interface2Method();
    }
}

public interface IMyInterface1<T>
{
    void Interface1Method();
}

public interface IMyInterface2<T>
{
    void Interface2Method();
}