• 簡介
  運用共享技術(shù)有效的支持大量細粒度的對象

• 應(yīng)用：當(dāng)一個應(yīng)用使用了大量的對象，而大量的這些對象造成了很大的存儲開銷的時候就應(yīng)該使用，還有就是對象的大多數(shù)狀態(tài)可以外部狀態(tài)，如果刪除對象的外部狀態(tài)，那么可以用相對較少的共享對象取代很多組對象，此時可以考慮使用享元模式。

• 代碼

//享元類的接口或者超累
abstract class Flyweight
{
    public abstract void Operation(int extrinsicstate);
}
//具體的實現(xiàn)子類
class ConcreteFlyweight :Flyweight
{
    private string name ="";
    public ConcreteFlyweight(string name){
        this.name = name;
    }

    public override void Operation(int extrinsicstate)
    {
        Console.WriteLine("具體 Flyweight:"+extrinsicstate);
    }
}
//不共享的子類,不共享類的存在是因為有些數(shù)據(jù)是不需要共享的。
class UnsharedConcreteFlyweight :Flyweight
{
    public override void Operation(int extrinsicstate)
    {
        Console.WriteLine("不共享的具體 Flyweight:"+extrinsicstate);
    }
}
//享元工廠類，創(chuàng)建并管理 Flyweight 對象
class FlyweightFactory
{
    private Hashtable flyweights = new Hashtable();

    public Flyweight GetFlyweight(string key)
    {
        if(!flyweights.ContainsKey(key))
            flyweights.Add(key,new ConcreteFlyweight(key))
        }
        return (Flyweight)flyweights(key);
    }
}
//客戶端調(diào)用
static void Main(string[] args){
    int num =  22;
    FlyweightFactory  f = new FlyweightFactory();
    Flyweight fx = f.GetFlyweight("X");
    fx.Operation(--num);
    Flyweight fy = f.GetFlyweight("Y");
    fy.Operation(--num);
    Flyweight uf = new UnsharedConcreteFlyweight();
    uf.Operation(--num);
    Console.Read();
}