设计模式之享元模式(Flyweight)

享元模式(Flyweight):运用共享技术有效地支持大量细粒度的对象。
Flyweight:所有具体享元类的超类或接口，通过这个接口，Flyweight可以接受并作用于外部状态
ConcreteFlyweight:继承Flyweight超类或实现Flyweight接口，并为内部状态增加存储空间。
UnsharedConcreteFlyweight:不需要共享的Flyweight子类。因为Flyweight接口共享成为可能，但不强制共享.
FlyweightFactory:享元工厂，用来创建并管理Flyweight对象。主要用来确保合理并共享Flyweight当用户请求一个Flyweight时，FlyweightFactory对象提供一个已创建的实例或者创建一个。
使用范围：1.如果一个应用程序使用了大量的对象，而大量的这些对象造成了很大的存储开销
2.对象的大多数状态可以外部状态，如果删除对象的外部状态，那么可以用相对较少的共享对象取代

Flyweight1.cs

using System;
using System.Data;
using System.Configuration;
using System.Collections;

//享元模式(Flyweight):运用共享技术有效地支持大量细粒度的对象。
//Flyweight:所有具体享元类的超类或接口，通过这个接口，Flyweight可以接受并作用于外部状态
//ConcreteFlyweight:继承Flyweight超类或实现Flyweight接口，并为内部状态增加存储空间。
//UnsharedConcreteFlyweight:不需要共享的Flyweight子类。因为Flyweight接口共享成为可能，但不
//强制共享.
//FlyweightFactory:享元工厂，用来创建并管理Flyweight对象。主要用来确保合理并共享Flyweight
//当用户请求一个Flyweight时，FlyweightFactory对象提供一个已创建的实例或者创建一个。
//使用范围：1.如果一个应用程序使用了大量的对象，而大量的这些对象造成了很大的存储开销
//2.对象的大多数状态可以外部状态，如果删除对象的外部状态，那么可以用相对较少的共享对象取代
namespace Flyweight
{
    class Flyweight1
    {
    }
    //Flyweight
    abstract class Flyweight
    {
        public abstract void Operation(int extrinsicstate);
    }
    //ConcreteFlyweight
    class ConcreteFlyweight : Flyweight
    {
        public override void Operation(int extrinsicstate)
        {
            Console.WriteLine("具体Flyweight" + extrinsicstate);
        }
    }
    //UnshareConcreteFlyweight
    class UnshareConcreteFlyweight : Flyweight
    {
        public override void Operation(int extrinsicstate)
        {
            Console.WriteLine("不共享的具体Flyweight:" + extrinsicstate);
        }
    }
    //FlyweightFactory
    class FlyweightFactory
    {
        private Hashtable flyweights = new Hashtable();

        public FlyweightFactory()
        {
            flyweights.Add("X", new ConcreteFlyweight());
            flyweights.Add("Y", new ConcreteFlyweight());
            flyweights.Add("Z", new ConcreteFlyweight());
        }

        public Flyweight GetFlyweight(string key)
        {
            return ((Flyweight)flyweights[key]);
        }
    }
}

 

Program.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace Flyweight
{
    class Program
    {
        static void Main(string[] args)
        {
            int extrinsicstate = 22;

            FlyweightFactory f = new FlyweightFactory();

            Flyweight fx = f.GetFlyweight("X");
            fx.Operation(--extrinsicstate);

            Flyweight fy = f.GetFlyweight("Y");
            fx.Operation(--extrinsicstate);

            Flyweight fz = f.GetFlyweight("Z");
            fz.Operation(--extrinsicstate);

            Flyweight ur = new UnshareConcreteFlyweight();

            ur.Operation(--extrinsicstate);

            Console.Read();
        }
    }
}

 

运行结果：

具体Flyweight21

具体Flyweight20

具体Flyweight19

不共享的具体Flyweight:18