/// <summary> /// 客戶端調(diào)用 /// </summary> class Client {  static void Main(string[] args)  {   // 定義外部狀態(tài)，例如字母的位置等信息   int externalstate = 10;   // 初始化享元工廠   FlyweightFactory factory = new FlyweightFactory();   // 判斷是否已經(jīng)創(chuàng)建了字母A，如果已經(jīng)創(chuàng)建就直接使用創(chuàng)建的對象A   Flyweight fa = factory.GetFlyweight("A");   if (fa != null)   {    // 把外部狀態(tài)作為享元對象的方法調(diào)用參數(shù)    fa.Operation(--externalstate);   }   // 判斷是否已經(jīng)創(chuàng)建了字母B   Flyweight fb = factory.GetFlyweight("B");   if (fb != null)   {    fb.Operation(--externalstate);   }   // 判斷是否已經(jīng)創(chuàng)建了字母C   Flyweight fc = factory.GetFlyweight("C");   if (fc != null)   {    fc.Operation(--externalstate);   }   // 判斷是否已經(jīng)創(chuàng)建了字母D   Flyweight fd= factory.GetFlyweight("D");   if (fd != null)   {    fd.Operation(--externalstate);   }   else   {    Console.WriteLine("駐留池中不存在字符串D");    // 這時候就需要創(chuàng)建一個對象并放入駐留池中    ConcreteFlyweight d = new ConcreteFlyweight("D");    factory.flyweights.Add("D", d);   }   Console.Read();  } } /// <summary> /// 享元工廠，負責(zé)創(chuàng)建和管理享元對象 /// </summary> public class FlyweightFactory {  // 最好使用泛型Dictionary<string,Flyweighy>  //public Dictionary<string, Flyweight> flyweights = new Dictionary<string, Flyweight>();  public Hashtable flyweights = new Hashtable();  public FlyweightFactory()  {   flyweights.Add("A", new ConcreteFlyweight("A"));   flyweights.Add("B", new ConcreteFlyweight("B"));   flyweights.Add("C", new ConcreteFlyweight("C"));  }  public Flyweight GetFlyweight(string key)  {// 更好的實現(xiàn)如下   //Flyweight flyweight = flyweights[key] as Flyweight;   //if (flyweight == null)   //{   // Console.WriteLine("駐留池中不存在字符串" + key);   // flyweight = new ConcreteFlyweight(key);   //}   //return flyweight;return flyweights[key] as Flyweight;  } } /// <summary> /// 抽象享元類，提供具體享元類具有的方法 /// </summary> public abstract class Flyweight {  public abstract void Operation(int extrinsicstate); } // 具體的享元對象，這樣我們不把每個字母設(shè)計成一個單獨的類了，而是作為把共享的字母作為享元對象的內(nèi)部狀態(tài) public class ConcreteFlyweight : Flyweight {  // 內(nèi)部狀態(tài)  private string intrinsicstate ;  // 構(gòu)造函數(shù)  public ConcreteFlyweight(string innerState)  {   this.intrinsicstate = innerState;  }  /// <summary>  /// 享元類的實例方法  /// </summary>  /// <param name="extrinsicstate">外部狀態(tài)</param>  public override void Operation(int extrinsicstate)  {   Console.WriteLine("具體實現(xiàn)類: intrinsicstate {0}, extrinsicstate {1}", intrinsicstate, extrinsicstate);  } }