设计模式之:享元模式FlyweightPattern的实现

享元模式的理解:

享元模式的定义:运用共享技术支持大量细粒度对象的复用;

Flyweight Pattern Definition:Use sharing to support large numbers of fine-grained efficiently.

享元模式关键词:大量、细粒度、复用、享元池、享元工厂

  1. 当系统中存在大量的细粒度的相同或相似对象时,可以使用享元模式;
  2. 享元模式通过共享技术,实现相同或相似对象的重复利用;
  3. 享元的字面理解:也就是分享共享的意思,就是共享的元素、对象;
  4. Flyweight的字面理解:Flyweight本意是拳击运动的一个术语,就是蝇量级的意思,flyweight 蝇量级 112磅;
  5. 享元模式也叫轻量级模式,享元是对Flyweight的意译,直译的话应该叫蝇量级模式;
  6. 英文定义中采用Flyweight,是想表达对象的粒度,也就是fine-grained细粒度的意思;
  7. grain本意表示谷物,grained表示像谷物那种颗粒状态,即粒度,而fine-grained则表示细粒度,例如fine grained soil 细土、coarse grained soil粗粒土;
  8. 享元模式和Unity中的预制体作用类似,享元模式可以通过共享元素生成多个对象,Unity同样可以通过Prefabs生成成千上万的怪物;
  9. 还有诸如对象池、线程池,实际上也是享元模式的使用案例;

类图with StarUML

《设计模式之:享元模式FlyweightPattern的实现》

棋子抽象类和2个实现类

    internal abstract class Chessman
    {
        public abstract string GetColor();
        public void Display() { Console.WriteLine($"棋子颜色{this.GetColor()}"); }
    }
    internal class BlackChessman : Chessman
    {
        public override string GetColor() { return "黑色"; }
    }
    internal class WhiteChessman : Chessman
    {
        public override string GetColor() { return "白色"; }
    }

享元工厂类

    internal class ChessmanFactory
    {
        //饿汉式单例模式
        private static ChessmanFactory instance = new ChessmanFactory();
        //该字典相当于享元池(对象池)Flyweight Pool
        private Dictionary<string, Chessman> dictionary;
        //构造注入依赖项Chessman/BlackChessman/WhiteChessman
        private ChessmanFactory()
        {
            dictionary = new Dictionary<string, Chessman>();
            Chessman black = new BlackChessman();
            Chessman white = new WhiteChessman();
            dictionary.Add("b", black);
            dictionary.Add("w", white);
        }
        //返回唯一实例
        public static ChessmanFactory GetInstance() { return instance; }
        //根据键是b还是w,返回字典中的对应棋子
        public Chessman GetChessman(string color) { return dictionary[color]; }
    }

客户端

    internal class Program
    {
        static void Main(string[] args)
        {
            Chessman black1, black2, white1, white2;
            ChessmanFactory factory = ChessmanFactory.GetInstance();
            //生成两颗黑子,并比较
            black1 = factory.GetChessman("b");
            black2 = factory.GetChessman("b");
            Console.WriteLine($"两颗黑子是否相同?{black1 == black2}");
            //生成两颗白字,并比较
            white1 = factory.GetChessman("w");
            white2 = factory.GetChessman("w");
            Console.WriteLine($"两颗白子是否相同?{black1 == black2}");
            //显示棋子
            black1.Display();
            black2.Display();
            white1.Display();
            white2.Display();

            Console.Read();
        }
    }

 

运行结果

《设计模式之:享元模式FlyweightPattern的实现》

 

    原文作者:张德长
    原文地址: https://www.cnblogs.com/zhangdezhang/p/16096206.html
    本文转自网络文章,转载此文章仅为分享知识,如有侵权,请联系博主进行删除。
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