我正在尝试在 MVC 4 Web Api 授权过滤器上实现依赖项注入。我创建了一个继承自 ActionDescriptorFilterProvider 的 FilterProvider:
public class UnityWebApiFilterAttributeFilterProvider : ActionDescriptorFilterProvider, System.Web.Http.Filters.IFilterProvider
{
private readonly IUnityContainer _container;
public UnityWebApiFilterAttributeFilterProvider(IUnityContainer container)
{
_container = container;
}
public IEnumerable<FilterInfo> GetFilters(HttpConfiguration configuration, HttpActionDescriptor actionDescriptor)
{
var filters = base.GetFilters(configuration, actionDescriptor);
this.BuildUpAttributes(filters);
return filters;
}
private void BuildUpAttributes(IEnumerable filterInfo)
{
foreach (FilterInfo filter in filterInfo)
{
object o = _container.BuildUp(filter.GetType(), filter);
}
}
}
我将此提供程序设置为 Global.asax 文件中的默认提供程序:
var providers = GlobalConfiguration.Configuration.Services.GetFilterProviders().ToList();
//Remove the default provider
var defaultprovider = providers.Single(i => i is ActionDescriptorFilterProvider);
GlobalConfiguration.Configuration.Services.Remove(typeof(System.Web.Http.Filters.IFilterProvider), defaultprovider);
//Add our custom provider
GlobalConfiguration.Configuration.Services.Add(typeof(System.Web.Http.Filters.IFilterProvider), new UnityWebApiFilterAttributeFilterProvider(new UnityContainer()));
我还在 AuthorizationFilter 中添加了依赖项:
public class WebApplicationApiAuthorizeAttribute : System.Web.Http.AuthorizeAttribute
{
[Dependency]
public IAuthorizationHelper AuthorizationHelper { get; set; }
#region OnAuthorization
public override void OnAuthorization(System.Web.Http.Controllers.HttpActionContext actionContext)
{
//Authorization code, which uses the AuthorizationHelper lives here
}
}
我在 Unity 配置文件中设置了映射:
container.RegisterType<WebApplicationApiAuthorizeAttribute>(new InjectionMember[]
{
new InjectionProperty("AuthorizationHelper", new ResolvedParameter<IAuthorizationHelper>())
});
container.RegisterType<IAuthorizationHelper, WebAuthorizationHelper>(new InjectionMember[]
{
new InjectionProperty("Cache", new ResolvedParameter<ICache>(cacheType)),
new InjectionProperty("UserSessionManager", new ResolvedParameter<IUserSessionManager>()),
new InjectionProperty("AuthorizationPermissionManager", new ResolvedParameter<IAuthorizationPermissionManager>()),
new InjectionProperty("ExceptionLogger", new ResolvedParameter<IExceptionLogger>()),
});
我可以看到 UnityWebApiFilterAttributeFilterProvider 类中的“BuildUpAttributes”方法被执行,并且过滤器被传递到 _container.BuildUp(...) 方法中,但是,WebApplicationApiAuthorizeAttribute 中的“IAuthorizationHelper”依赖项没有得到解析。当我调试 WebApplicationApiAuthorizeAttribute 时,它为空。
那么为什么这种依赖性没有得到解决呢?