1、Subject类，主题或者抽象通知者

public abstract class Subject

{

private IList<Observer> observers = new List<Observer>();

/// <summary>

/// 添加观察者

/// </summary>

/// <param name="observer">观察者</param>

public void Attach(Observer observer)

{

observers.Add(observer);

}

/// <summary>

/// 移除观察者

/// </summary>

/// <param name="observer">观察者</param>

public void Detach(Observer observer)

{

observers.Remove(observer);

}

/// <summary>

/// 通知观察者

/// </summary>

public void Notify()

{

foreach (Observer o in observers)

{

o.Update();

}

}

}

2、ConcreteSubject类，具体主题或者具体通知者

public class ConcreteSubject:Subject

{

private string _subjectState;

/// <summary>

/// 具体被观察者状态

/// </summary>

public string SubjectState

{

get { return _subjectState; }

set { _subjectState = value; }

}

}

3、Observer抽象观察者，为所有的具体观察者定义一个接口

public abstract class Observer

{

public abstract void Update();

}

4、ConcreteObserver具体观察者

/// <summary>

/// 具体观察者，实现抽象观察者角色所要求的更新接口

/// 以便使本身的状态与主题的状态相协调

/// </summary>

public class ConcreteObserver:Observer

{

private string name;

private string observerState;

private ConcreteSubject subject;

public ConcreteSubject Subject

{

get { return subject; }

set { subject = value; }

}

public ConcreteObserver(ConcreteSubject subject,string name)

{

this.subject = subject;

this.name = name;

}

public override void Update()

{

observerState = subject.SubjectState;

Console.WriteLine("观察者{0}的新状态是{1}",name,observerState);

}

}

5、客户端代码

static void Main(string[] args)

{

ConcreteSubject cs = new ConcreteSubject();

cs.Attach(new ConcreteObserver(cs,"James"));

cs.Attach(new ConcreteObserver(cs,"Jane"));

cs.SubjectState="OK";

cs.Notify();

Console.Read();

}

1、Stock股票类

public class Stock

{

private double _openPrice;

private double _closePrice;

public delegate void PriceChangedHandler(object sender, StockDetailArgs e);

public event PriceChangedHandler PriceChanged;

public double OpenPrice

{

get { return _openPrice; }

set { _openPrice = value; }

}

public double ClosePrice

{

get { return _closePrice; }

set { _closePrice = value; }

}

public void StartTrading()

{

double current;

//Current price decrements by $1.00 as the stock is traded

current = OpenPrice;

while (current > ClosePrice)

{

//Stock is falling in increments of $1.00

current = current - 1.00;

//Call the method to raise the event

OnPriceChanged(current);

//Simulate a delay of 2000ms between market price updates

System.Threading.Thread.Sleep(2000);

}

}

protected void OnPriceChanged(double currentMarketPrice)

{

//Any handlers attached to this event?

if (PriceChanged != null)

{

StockDetailArgs args = new StockDetailArgs();

args.CurrentPrice = currentMarketPrice;

Console.WriteLine("当前股票价格是：" + args.CurrentPrice.ToString());

////Raise the event

PriceChanged(this, args);

}

}

/// <summary>

/// 添加观察者

/// </summary>

/// <param name="observer">观察者</param>

public void AttachEvent(IObserver observer)

{

PriceChanged += new PriceChangedHandler(observer.Stoc_PriceChanged);

}

}

2、事件参数StockDetailArgs

public class StockDetailArgs: EventArgs

{

private double _currentPrice;

public double CurrentPrice

{

get { return _currentPrice; }

set { _currentPrice = value; }

}

}

3、观察者接口IObserver

public interface IObserver

{

void Stoc_PriceChanged(object sender, StockDetailArgs e);

}

4、具体观察者Observer

public class Observer : IObserver

{

private string _investorName;

private double _buyPrice;

private Stock _stoc;

private bool _hasBoughtStock = false;

public string InvestorName

{

get { return _investorName; }

set { _investorName = value; }

}

public double BuyPrice

{

get { return _buyPrice; }

set { _buyPrice = value; }

}

public Stock Stoc

{

get { return _stoc; }

set { _stoc = value; }

}

public Observer(string investorName, double buyPrice)

{

this.InvestorName = investorName;

this.BuyPrice = buyPrice;

}

public void Stoc_PriceChanged(object sender, StockDetailArgs e)

{

if (e.CurrentPrice <= BuyPrice && _hasBoughtStock == false)

{

Console.WriteLine(string.Format("{0}在价格Price ={1}时买进了股票。",InvestorName,e.CurrentPrice));

_hasBoughtStock = true;

}

}

}

5、客户端代码

static void Main(string[] args)

{

Stock stock = new Stock();

stock.OpenPrice = 16.50;

stock.ClosePrice = 5.50;

Observer james = new Observer("灵动生活", 12.00);

Observer jane = new Observer("jane",8.05);

stock.AttachEvent(james);

stock.AttachEvent(jane);

stock.StartTrading();

Console.Read();

}