反射 通过父类获取所有子类

 public void AddStates()
        {

            var subTypeQuery = from t in Assembly.GetExecutingAssembly().GetTypes()
                               where IsSubClassOf(t, typeof(State))
                               select t;

            foreach (var type in subTypeQuery)
            {
                var stateObj = Activator.CreateInstance(type) as State;
                stateObj.Action();
                if (!states.Contains(stateObj))
                    states.Add(stateObj);
            }
        }

        static bool IsSubClassOf(Type type, Type baseType)
        {
            var b = type.BaseType;
            while (b != null)
            {
                if (b.Equals(baseType))
                {
                    return true;
                }
                b = b.BaseType;
            }
            return false;
        }