Autofac在asp.net的MVC Web API返回不同的实例

我使用autofac在一个asp.net MVC和的WebAPI项目。

I'm using autofac in an asp.net mvc and webapi project.

在配置我这样做：

var builder = new ContainerBuilder();
builder.Register(x => NHibernateConfigurator.BuildSessionFactory()).SingleInstance();
builder.Register(x => x.Resolve<ISessionFactory>().OpenSession()).InstancePerHttpRequest();
builder.RegisterSource(new AnyConcreteTypeNotAlreadyRegisteredSource());

builder.RegisterControllers(Assembly.GetExecutingAssembly());
builder.RegisterApiControllers(Assembly.GetExecutingAssembly());

var container = builder.Build();

DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
config.DependencyResolver = new AutofacWebApiDependencyResolver(container);

现在的问题是，在API控制器，​​如果我通过建筑工注入的ISession也叫

Now the problem is that in an api controller if I inject ISession via the constructer and also call

DependencyResolver.Current.GetService<ISession>() 

它会返回2不同的实例。

it will return 2 different instances.

我猜这个问题是因为这些2行：

I'm guessing the problem is because of these 2 lines :

DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
config.DependencyResolver = new AutofacWebApiDependencyResolver(container);

但我怎么可以让它返回同一个实例？

But how can I make it return the same instance ?

编辑：

只是要更清楚 - 我期待的ISession每Htt的prequest相同的实例。现在，我在同样的要求得到不同的实例。

Just to be more clear - I'm expecting the same instance of ISession per HttpRequest. Right now I'm getting different instances on the same request.

感谢