笔记-大话设计模式-26 享元模式

享元模式(Flyweight)，运用共享技术有效地支持大量细粒度的对象。

缺点：使得系统更加复杂；使得程序逻辑复杂化。

Demo:

    abstract class Website
    {
        public abstract void Use(User user);
    }

    class ConcreteWebsite : Website
    {
        private string name;

        public ConcreteWebsite(string name)
        {
            this.name = name;
        }

        public override void Use(User user)
        {
            Console.WriteLine("网站分类：{0}，用户：{1}", name,user.Name);
        }

    }

    class User
    {
        private string name;

        public User(string name)
        {
            this.name = name;
        }

        public string Name
        {
            get { return name; }
        }

    }

    class WebsiteFactory
    {
        private Hashtable flyweights = new Hashtable();

        public Website GetWebsite(string key)
        {
            if (!flyweights.ContainsKey(key))
            {
                flyweights.Add(key, new ConcreteWebsite(key));
            }
            return (Website)flyweights[key];
        }

        public int GetWebsiteCount()
        {
            return flyweights.Count;
        }

    }

Test:

            WebsiteFactory wf = new WebsiteFactory();

            Website web = wf.GetWebsite("企业网站");
            web.Use(new User("Jack"));
            Website web2 = wf.GetWebsite("企业网站");
            web2.Use(new User("Meili"));
            Console.WriteLine("网站分类总数：{0}", wf.GetWebsiteCount());