c# - 从 Unity 获取接口(interface)实例

Question

我正在尝试在我的 MVC 应用程序中设置自定义身份验证过滤器，但我需要在身份验证过滤器中引用我的用户服务。我像这样使用 Unity 设置我的服务:

    private static Lazy<IUnityContainer> container = new Lazy<IUnityContainer>(() =>
    {
        var container = new UnityContainer();
        RegisterTypes(container);
        return container;
    });

    public static IUnityContainer GetConfiguredContainer()
    {
        return container.Value;
    }

    public static void RegisterTypes(IUnityContainer container)
    {

        // container.LoadConfiguration();

        // TODO: Register your types here
        container.RegisterType<IUserService, UserService>();

    }

[assembly: WebActivatorEx.PreApplicationStartMethod(typeof(GERPWeb.App_Start.UnityWebActivator), "Start")]
[assembly: WebActivatorEx.ApplicationShutdownMethod(typeof(GERPWeb.App_Start.UnityWebActivator), "Shutdown")]

namespace APP.App_Start
{
/// <summary>Provides the bootstrapping for integrating Unity with ASP.NET MVC.</summary>
public static class UnityWebActivator
{
    /// <summary>Integrates Unity when the application starts.</summary>
    public static void Start() 
    {
        var container = UnityConfig.GetConfiguredContainer();

        FilterProviders.Providers.Remove(FilterProviders.Providers.OfType<FilterAttributeFilterProvider>().First());
        FilterProviders.Providers.Add(new UnityFilterAttributeFilterProvider(container));

        DependencyResolver.SetResolver(new UnityDependencyResolver(container));

        // TODO: Uncomment if you want to use PerRequestLifetimeManager
        // Microsoft.Web.Infrastructure.DynamicModuleHelper.DynamicModuleUtility.RegisterModule(typeof(UnityPerRequestHttpModule));
    }

    /// <summary>Disposes the Unity container when the application is shut down.</summary>
    public static void Shutdown()
    {
        var container = UnityConfig.GetConfiguredContainer();
        container.Dispose();
    }
}

只要我有一个构造函数，它就可以正常工作，就像这样:

public class UserController : BaseController
{

    private readonly IUserService _userService;

    public CustomerController(IUserService userService)
    {
        _userService = userService;

    }

但是我的身份验证过滤器中不能有:

public class BasicAuthorization : AuthorizeAttribute
{
    public override void OnAuthorization(AuthorizationContext filterContext)
    {
        //see if we can skip the authorization
        bool skipAuthorization = filterContext.ActionDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true) ||
                                 filterContext.ActionDescriptor.ControllerDescriptor.IsDefined(
                                     typeof(AllowAnonymousAttribute), true);

        if (!skipAuthorization)
        {
            //var userService = ServiceLocator.Current.GetInstance<IUserService>();
            //get instance of user service here


            base.OnAuthorization(filterContext);
        }
    }
}

然后在我的 FilterConfig.cs 中:

    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new BasicAuthorization());
        filters.Add(new HandleErrorAttribute());
    }

我找到了对称为服务定位器的东西的引用，并尝试尽我所能使用它，但我认为我遗漏了一些东西，因为我得到 ServiceLocationProvider must be set. 在该行，所有的谷歌链接都是针对 WPF 的。

我在这里错过了什么？

Answer 1

您已经设置了基本上遵循服务定位器模式的 DependencyResolver。

public class BasicAuthorization : AuthorizeAttribute {
    public override void OnAuthorization(AuthorizationContext filterContext) {
        //see if we can skip the authorization
        bool skipAuthorization = filterContext.ActionDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true) ||
                                 filterContext.ActionDescriptor.ControllerDescriptor.IsDefined(
                                     typeof(AllowAnonymousAttribute), true);

        if (!skipAuthorization) {
            //Using dependency resolver here
            var userService = (IUserService) DependencyResolver.Current.GetService(typeof(IUserService));


            base.OnAuthorization(filterContext);
        }
    }
}

您可以创建一个扩展方法以允许更清晰地解析实例

public static T GetService<T>(this IDependencyResolver container) {
    return (T)container.GetService(typeof(T));
}

这将允许

var userService = DependencyResolver.Current.GetService<IUserService>();