使用 ASP.New MVC 4 Web Api 进行授权过滤器依赖注入

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？

您的代码中有两个错误。

1. 你正在建立FilterInfo对象而不是它的Instance http://msdn.microsoft.com/en-us/library/system.web.http.filters.filterinfo.instance%28v=vs.118%29.aspx:

   foreach (FilterInfo filter in filterInfo)
   {
       object o = _container.BuildUp(filter.GetType(), filter);
   }
   

   但这是正确的代码：

   foreach (FilterInfo filter in filterInfo)
   {
       _container.BuildUp(filter.Instance.GetType(), filter.Instance);
   }
   

2. 您的定制UnityWebApiFilterAttributeFilterProvider得到一个新的空容器：

   GlobalConfiguration.Configuration.Services.Add(
       typeof(System.Web.Http.Filters.IFilterProvider), 
       new UnityWebApiFilterAttributeFilterProvider(new UnityContainer()));
   

   但您应该传递应用程序的配置容器：

   GlobalConfiguration.Configuration.Services.Add(
       typeof(System.Web.Http.Filters.IFilterProvider), 
       new UnityWebApiFilterAttributeFilterProvider(container));