弱事件管理器及WeakEventManager,IWeakEventListener的使用

CarDealer类发布事件，Consumer类（实现IWeakEventListener接口）订阅事件

实现代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Windows;

namespace ConsoleDelegate
{
    class Program
    {
        static void Main(string[] args)
        {
            CarDealer dealer = new CarDealer("Obama");
            Consumer Jack = new Consumer("Jack");
            WeakCarInfoEventManager.AddListener(dealer, Jack);
            dealer.NewCar("BMW");

            Consumer Bidden = new Consumer("Bidden");
            WeakCarInfoEventManager.AddListener(dealer, Bidden);
            dealer.NewCar("EAGLE");
        }
    }

    public class CarInfoEventArgs : EventArgs
    {
        public CarInfoEventArgs(string name)
        {
            this.Car = name;
        }

        public string Car { get; private set; }
    }

    public class CarDealer
    {
        private string name;
        public CarDealer(string name)
        {
            this.name = name;
        }

        public event EventHandler<CarInfoEventArgs> NewCarInfo;
        public void NewCar(string car)
        {
            Console.WriteLine("{0}, New Car: {1}", name, car);
            NewCarInfo(this, new CarInfoEventArgs(car));
        }
    }

    public class Consumer : IWeakEventListener
    {
        private string name;
        public Consumer(string name)
        {
            this.name = name;
        }

        private void NewCarIsHere(object sender, CarInfoEventArgs e)
        {
            Console.WriteLine("{0}, new car :{0} is here............", name, e.Car);
        }

        bool IWeakEventListener.ReceiveWeakEvent(Type managerType, object source, EventArgs e)
        {
            NewCarIsHere(source, e as CarInfoEventArgs);
            return true;
        }
    }

    public class WeakCarInfoEventManager : WeakEventManager
    {
        public static void AddListener(object source,IWeakEventListener e)
        {
            CurrentManager.ProtectedAddListener(source, e);
        }

        public static void RemoveListener(object source, IWeakEventListener e)
        {
            CurrentManager.ProtectedRemoveListener(source, e);
        }

        public static WeakCarInfoEventManager CurrentManager
        {
            get
            {
                WeakCarInfoEventManager manager = GetCurrentManager(typeof(WeakCarInfoEventManager)) 
                    as WeakCarInfoEventManager;
                if(manager ==null)
                {
                    manager = new WeakCarInfoEventManager();
                    SetCurrentManager(typeof(WeakCarInfoEventManager), manager);
                }

                return manager;
            }
        }

        protected override void StartListening(object source)
        {
            (source as CarDealer).NewCarInfo += CarDealer_NewCarInfo;
        }

        public void CarDealer_NewCarInfo(object sender, CarInfoEventArgs e)
        {
            DeliverEvent(sender, e);
        }

        protected override void StopListening(object source)
        {
            (source as CarDealer).NewCarInfo += CarDealer_NewCarInfo;
        }
    }
}