如何使用静态工厂方法创建对象？

Question

我知道Unity可以配置为使用类的构造函数来创建类的实例(如下所示),但这不是我想要的.

container.RegisterType<IAuthoringRepository, AuthoringRepository>();

我想将Unity配置为使用工厂方法,将windows身份作为参数传递(即RepositoryFactory.CreateAuthoringRepository(WindowsIdentity.GetCurrent()):),解析一种类型的IAuthoringRepository.我该怎么做呢？

Answer 1

一种方法是让RepositoryFactory实现IRepositoryFactory,然后注册它.已解析的类型可以获取工厂,然后调用其CreateAuthoringRepository方法.如果需要,您可以创建一个名为CreateAuthoringRepositoryForCurrentIdentity的重载,或者使用Unity注册工厂的IIdentity依赖项.

我可能只是注入一个工厂并保留CreateAuthoringRepository方法,然后让客户端通过WindowsIdentity.GetCurrent().这样,身份总是很新鲜,你可以嘲笑工厂进行测试.

或者,您可以使用InjectionFactory指定委托:

void Main()
{
    using (var container = new UnityContainer())
    {
        container.RegisterType<IAuthoringRepository>(
            new InjectionFactory(c => CreateAuthoringRepository()));

        Console.WriteLine("debug - resolving model");
        var model = container.Resolve<Model>();
    }
}

public IAuthoringRepository CreateAuthoringRepository()
{
    Console.WriteLine("debug - calling factory");
    return new AuthoringRepository
        { Identity = WindowsIdentity.GetCurrent() };
}

public class Model
{
    public Model(IAuthoringRepository repository)
    {
        Console.WriteLine(
            "Constructing model with repository identity of "
            + repository.Identity);
    }
}

public interface IAuthoringRepository
{
    IIdentity Identity { get; }
}

public class AuthoringRepository : IAuthoringRepository
{
    public IIdentity Identity { get; set; }
}

这打印:

debug - resolving model
debug - calling factory
Constructing model with repository identity of System.Security.Principal.WindowsIdentity

这是针对Unity 2.0的.对于早期版本,请参阅StaticFactoryExtension.