复制代码 代码如下:
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();
}
}
}