简单的观察者模式示例分享

using system;
using system.collections.generic;

namespace demo
{
    #region 抽象层,定义了观察者模式
    /// <summary>
    /// （抽象）新闻
    /// </summary>
    public interface inews
    {
        void subscribe(isubscriber s);
        void unsubscribe(isubscriber s);
        void publish(string newstitle);   //在具体实现的过程中建立发布与订阅的联系
    }

    /// <summary>
    /// (抽象）订阅者
    /// </summary>
    public interface isubscriber
    {
        void read(string newstitle);
    }
    #endregion

    #region 实现层,是对抽象层的具体实现
    /// <summary>
    /// （具体）新闻
    /// </summary>
    public class itnews : inews
    {
        private list<isubscriber> readers = new list<isubscriber>();

        public void subscribe(isubscriber s)
        {
            readers.add(s);
        }

        public void unsubscribe(isubscriber s)
        {
            if (readers.count >= 0)
            {
                readers.remove(s);
            }
        }

        public void publish(string newstitle)
        {
            foreach (isubscriber i in readers)
            {
                i.read(newstitle);          //<<<<<发布的时候订阅>>>>>
            }
        }
    }

    /// <summary>
    /// (具体)订阅者
    /// </summary>
    public class subscriber : isubscriber
    {
        private string subscriber = string.empty;
        public subscriber(string subscriber)
        {
            this.subscriber = subscriber;
        }

        public void read(string newstitle)
        {
            console.writeline(string.format("{0}阅读了it新闻\"{1}\"", subscriber, newstitle));
        }
    }
    #endregion

    public class pro
    {
        static void main(string[] args)
        {
            itnews news = new itnews();
            subscriber zs = new subscriber("张三"),
                                 ls = new subscriber("李四"),
                                 ww = new subscriber("王五");

            news.subscribe(zs);
            news.subscribe(ls);
            news.subscribe(ww);
            news.unsubscribe(ls);  //张三取消订阅

            news.publish("2014年移动电商攻坚战：阿里巴巴如何破局？");
            news.publish("余额宝还能重回高收益率吗？");

            console.writeline();
            console.readkey();
        }
    }
}