如何基于同一个服务注册和解析多个组件

Question

我有一个缓存的存储库，它实现了与真实存储库相同的接口。即

public class CachedLocationRepository : ILocationRepository
public class LocationRepository : ILocationRepository

如何向 Autofac 注册两者并告诉特定服务使用哪个组件？

即一些组件使用真实版本，一些使用缓存版本。

public class UseRealImpl : IUseRealImpl
{
    public UseRealImpl(ILocationRepository locationRepository) 
    {
    }
}

public class UseCachedImpl : IUseCachedImpl
{
    public UseCachedImpl(ILocationRepository cachedLocationRepository) 
    {
    }
}

Answer 1

您可以为此使用密钥服务：Named and Keyed Services

例如：

ContainerBuilder builder = new ContainerBuilder();
builder.RegisterType<CachedLocationRepository>()
       .As<ILocationRepository>()
       .Keyed<ILocationRepository>(RepositoryType.Cached);
builder.RegisterType<LocationRepository>()
       .As<ILocationRepository>()
       .Keyed<ILocationRepository>(RepositoryType.Real);

然后你可以使用参数注册UseCachedImpl :

builder.RegisterType<UseCachedImpl>()
       .As<UseCachedImpl>()
       .WithParameter((pi, c) => pi.ParameterType == typeof(ILocationRepository)
                     ,(pi, c) => c.ResolveKeyed<ILocationRepository>(RepositoryType.Cached));

或使用WithKeyAttribute

public class UseCachedImpl 
{
    public UseCachedImpl([WithKey(RepositoryType.Cached)]ILocationRepository cachedLocationRepository) 
    {
    }
}

或者创建一个 Module，它将根据条件自动添加参数，例如，如果服务实现了某个接口。

如何基于同一个服务注册和解析多个组件

How to register and resolve multiple components based on same service

c#

dependency-injection

inversion-of-control

autofac