用Observer实现的Stock代码

Stock

public delegate void PriceChangeDelegate(Stock aStock);
    public class Stock
    {
        public event PriceChangeDelegate PriceChangeHandler;
        protected string symbol;
        protected double price;

        public Stock( string symbol, double price )
        {
            this.symbol = symbol;
            this.price = price;
        }
        public void Notify()
        {
            if(PriceChangeHandler != null)
                PriceChangeHandler(this);
        }
        // Properties
        public double Price
        {
            get{ return price; }
            set{ price = value;}
        }

        public string Symbol
        {
            get{ return symbol; }
            set{ symbol = value; }
        }
    }

Inversotr

interface IInvestor
    {
        void Update(Stock aStock);
    }

    public class  Inverstor : IInvestor
    {
        private string name;

        // Constructors
        public Inverstor( string name )
        {
            this.name = name;
        }

        IInvestor 成员#region IInvestor 成员

        public void Update(Stock aStock)
        {
            // TODO:  添加 Inverstor.Update 实现
            Console.WriteLine("Notified investor {0} of {1}'s + change to {2:C}",
                name, aStock.Symbol, aStock.Price );
        }
        #endregion

    }

前台程序

            ObserverAdvance.Inverstor Koffer = new ObserverAdvance.Inverstor("My WebSite");
            ObserverAdvance.Stock HuaxiaStock = new ObserverAdvance.Stock("HuaXiaIT",100);
            HuaxiaStock.PriceChangeHandler += new ObserverAdvance.PriceChangeDelegate(Koffer.Update);
            
            HuaxiaStock.Price = 200;
            HuaxiaStock.Notify();