确定解析实例的依赖关系 - IoC(autofac)

Question

有没有办法确定哪个调用者/依赖项正在解析它所依赖的实例？这就是我的想法

public class A
{
    public A()
    {
        Console.Write("I am being resolved by {0}");
    }
}

public class B
{    
    public B(A a)
    {
        //Should print: A being resolved by B
    }
}


public class C
{
    public C(A a)
    {
    //Should print: A being resolved by C
    }
}

我猜测在多个依赖项之间共享的单个实例可能有点棘手,但我特意查找每个依赖项解析的实例,因此在上面的示例中将有两个B实例.

FWIW,我的IoC容器是Autofac,它在MVC Web应用程序的上下文中运行

Answer 1

您可以使用ResolveOperationBegging和InstanceLookupBeginning事件

    ContainerBuilder builder = new Autofac.ContainerBuilder();
    builder.RegisterType<A>().AsSelf();
    builder.RegisterType<B>().AsSelf();
    builder.RegisterType<C>().AsSelf();

    IContainer container = builder.Build();

    EventHandler<LifetimeScopeBeginningEventArgs> lifetimeScopeBeginning = null;
    lifetimeScopeBeginning = (sender, e) =>
    {
        e.LifetimeScope.ResolveOperationBeginning += (sender2, e2) =>
        {
            List<IInstanceActivator> activators = new List<IInstanceActivator>();
            e2.ResolveOperation.InstanceLookupBeginning += (sender3, e3) =>
            {
                activators.Add(e3.InstanceLookup.ComponentRegistration.Activator);
                Console.WriteLine("Activation Path : {0}", String.Join(" => ", activators.Select(a => a.LimitType.Name).ToArray()));
            };
        };
        e.LifetimeScope.ChildLifetimeScopeBeginning += lifetimeScopeBeginning;
    };
    container.ChildLifetimeScopeBeginning += lifetimeScopeBeginning;

    using (ILifetimeScope scope = container.BeginLifetimeScope())
    {
        scope.Resolve<C>();
    }

此代码将显示

Activation Path : C
Activation Path : C => B
Activation Path : C => B => A