WCF + Unity嵌套了web.config问题

Question

我正在尝试设置以下内容：

/WebApplication
    web.config
    tokenlogin.aspx
    /Services
        web.config
        AccessTokenService.svc

我将我的WCF服务+配置放在/ WebApplication / Services文件夹中。

这仍然按预期工作。

现在我的AccessTokenService驻留在另一个程序集中，它的构造函数中需要一个名为IAccessTokenRepository的接口（参见下面的所有代码示例）。

因为通常WCF只允许无参数构造函数，所以我使用自定义IInstanceProvider，IServiceBehavior和BehaviorExtensionElement扩展了WCF，因此Unity可以为我解决这个问题。

正如我对WCF配置所做的那样，我还将Unity配置放在了驻留在Services文件夹中的web.config文件中。这样我就不会在我的web应用程序根目录中污染我的web.config。但这似乎不起作用。我无法从services文件夹中的web.config读取unity配置部分。 以下代码的GetSection部分返回null：

public class UnityBehaviorExtensionElement : BehaviorExtensionElement
{
    public override Type BehaviorType
    {
        get { return typeof(UnityServiceBehaviour); }
    }

    protected override object CreateBehavior()
    {   
        UnityContainer unityContainer = new UnityContainer();
        UnityConfigurationSection section = LoadUnitySection() as UnityConfigurationSection;
        section.Containers.Default.Configure(unityContainer);
        return new UnityServiceBehaviour(unityContainer);

    }

    private object LoadUnitySection()
    {
        if (System.Web.Hosting.HostingEnvironment.IsHosted)            
            return WebConfigurationManager.GetSection("unity");            
        return ConfigurationManager.GetSection("unity");
    }
}

现在，如果我将统一配置移动到web.config的根目录，那么WebApplication的根目录一切正常。我不明白为什么。

其余代码：

[ServiceContract(Namespace = "http://services.xxx.com/AccessTokenService/1.0")]
public interface IAccessTokenService
{
    [OperationContract]
    Guid RequestAccessToken(AccessTokenRequest accessTokenRequest);
}

public class AccessTokenService : IAccessTokenService
{
    private readonly IAccessTokenRepository accessTokenRepository;

    public AccessTokenService(IAccessTokenRepository accessTokenRepository)
    {
        if (accessTokenRepository == null)
            throw new ArgumentNullException("accessTokenRepository");

        this.accessTokenRepository = accessTokenRepository;
    }

    public Guid RequestAccessToken(AccessTokenRequest accessTokenRequest)
    {
        return accessTokenRepository.Store(accessTokenRequest);
    }     
}   

public class UnityInstanceProvider : IInstanceProvider
{
    private readonly Type serviceType;
    private readonly UnityContainer unityContainer;

    public UnityInstanceProvider(Type serviceType, UnityContainer unityContainer)
    {
        this.serviceType = serviceType;
        this.unityContainer = unityContainer;
    }

    #region IInstanceProvider Members

    public object GetInstance(InstanceContext instanceContext, System.ServiceModel.Channels.Message message)
    {
        return unityContainer.Resolve(serviceType);
    }

    public object GetInstance(InstanceContext instanceContext)
    {
        return GetInstance(instanceContext, null);
    }

    public void ReleaseInstance(InstanceContext instanceContext, object instance)
    {
        if (instance == null)
            return;

        if (instance is IDisposable)
            ((IDisposable)instance).Dispose();
    }

    #endregion
}

public class UnityServiceBehaviour : IServiceBehavior
{
    private readonly UnityContainer unityContainer;

    public UnityServiceBehaviour(UnityContainer unityContainer)
    {
        this.unityContainer = unityContainer;
    }

    public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, Collection endpoints, BindingParameterCollection bindingParameters)
    {

    }

    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {
        foreach (var channel in serviceHostBase.ChannelDispatchers.OfType())
        {
            if (channel == null)
                continue;

            foreach (var endPointDispatcher in channel.Endpoints)
            {
                endPointDispatcher.DispatchRuntime.InstanceProvider =
                    new UnityInstanceProvider(serviceDescription.ServiceType, unityContainer);
            }
        }
    }

    public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {

    }        
}