ActionInterceptor.cs

using System;
using System.Linq;
using System.Web.Mvc;
using Castle.DynamicProxy;

public abstract class ActionInterceptor : IInterceptor, IActionFilter, IResultFilter {

  public void Intercept(IInvocation invocation) {
    switch (invocation.Method.Name) {
      case "OnActionExecuting":
        Intercept(invocation, OnActionExecuting);
        break;
      case "OnActionExecuted":
        Intercept(invocation, OnActionExecuted);
        break;
      case "OnResultExecuting":
        Intercept(invocation, OnResultExecuting);
        break;
      case "OnResultExecuted":
        Intercept(invocation, OnResultExecuted);
        break;
    }
    invocation.Proceed();
  }

  void Intercept<TContext>(IInvocation invocation, Action<TContext> action) {
    action(invocation.Arguments.First() as TContext);
  }

  public virtual void OnActionExecuting(ActionExecutingContext filterContext) {

  }

  public virtual void OnActionExecuted(ActionExecutedContext filterContext) {

  }

  public virtual void OnResultExecuting(ResultExecutingContext filterContext) {

  }

  public virtual void OnResultExecuted(ResultExecutedContext filterContext) {

  }
}