天天向上

   1: interface ISubject

   2: {

   3:     void Register(IObserver o);

   4:     void Unregister(IObserver o);

   5:     void NotifyObserver();

   6: }

   1: interface Observer

   2: {

   3:     void Update(double ibmPrice, double appPrice, double googPrice);

   4: }

   1: class StockGrabber : ISubject

   2: {

   3:     IList<IObserver> observers;

   4:     private double ibmPrice;

   5:     private double appPrice;

   6:     private double googPrice;

   7:     public StockGrabber()

   8:     {

   9:         observers = new List<IObserver>();

  10:         ibmPrice = 0;

  11:         appPrice = 0;

  12:         googPrice = 0;

  13:     }

  14:     public void NotifyObserver()

  15:     {

  16:         foreach(IObserver observer in observers)

  17:         {

  18:             observer.Update(ibmPrice, appPrice, googPrice);

  19:         }

  20:     }

  21:     public void setIBMPrice(double ibmPrice)

  22:     {

  23:         this.ibmPrice = ibmPrice;

  24:         NotifyObserver();

  25:     }

  26:     public void setAPPPrice(double appPrice)

  27:     {

  28:         this.appPrice = appPrice;

  29:         NotifyObserver();

  30:     }

  31:     public void setGOOGPrice(double googPrice)

  32:     {

  33:         this.googPrice = googPrice;

  34:         NotifyObserver();

  35:     }

  36:     public void Register(IObserver newObserver)

  37:     {

  38:         observers.Add(newObserver);

  39:     }

  40:  

  41:     public void Unregister(IObserver deleteObserver)

  42:     {

  43:         int observerIndex = observers.IndexOf(deleteObserver);

  44:         Console.WriteLine("Observer {0} deleted", observerIndex+1);

  45:         observers.RemoveAt(observerIndex);

  46:     }

  47: }

   1: class StockObserver : IObserver

   2: {

   3:     double ibmPrice;

   4:     double appPrice;

   5:     double googPrice;

   6:     static int observerIDTracker = 0;

   7:     ISubject stockGrabber;

   8:     int observerID;

   9:  

  10:     public StockObserver(ISubject stockGrabber)

  11:     {

  12:         this.stockGrabber = stockGrabber;

  13:         this.observerID = ++observerIDTracker;

  14:         Console.WriteLine("New Observer {0}", this.observerID);

  15:         stockGrabber.Register(this);

  16:     }

  17:     public void Update(double ibmPrice, double appPrice, double googPrice)

  18:     {

  19:         this.ibmPrice = ibmPrice;

  20:         this.appPrice = appPrice;

  21:         this.googPrice = googPrice;

  22:         printThePrices();

  23:     }

  24:     private void printThePrices()

  25:     {

  26:         Console.WriteLine("#{0} \n IBM:{1}\n Apple:{2}\n Google:{3}", 

  27:             observerID, this.ibmPrice, this.appPrice, this.googPrice);

  28:     }

  29: }

   1: static void Main(string[] args)

   2: {

   3:    StockGrabber stockGrabber = new StockGrabber();

   4:    StockObserver observer1 = new StockObserver(stockGrabber);

   5:    stockGrabber.setIBMPrice(197.00);

   6:    stockGrabber.setAPPPrice(677.60);

   7:    stockGrabber.setGOOGPrice(676.40);

   8:  

   9:    StockObserver observer2 = new StockObserver(stockGrabber);

  10:    stockGrabber.setIBMPrice(197.00);

  11:    stockGrabber.setAPPPrice(677.60);

  12:    stockGrabber.setGOOGPrice(676.40);

  13:  

  14:    stockGrabber.Unregister(observer2);

  15:    stockGrabber.setIBMPrice(100);

  16:    stockGrabber.setAPPPrice(500.60);

  17:    stockGrabber.setGOOGPrice(600.40);

  18:  

  19:    Console.ReadKey();

  20: }