c#中观查者模式实现（委托版）

using System;

using System.Collections.Generic;

using System.Text;

namespace ObserverDemo

{

class 观查者模式委托版

{

public static void Main(string[] args)

{

BankAccount count = new BankAccount();

count.WithDrawEvent += new BankAccount.WithDrawEventHandler( new Email().Update);

count.WithDraw(50);

Console.Read();

}

}

abstract class ISubject

{

public delegate void WithDrawEventHandler(object sender, UserMsgInfoEventArgs args);

public event WithDrawEventHandler WithDrawEvent;

public void OnWithDrawEvent(UserMsgInfoEventArgs args)

{

if (this.WithDrawEvent != null)

{

this.WithDrawEvent(this, args);

}

}

}

class BankAccount : ISubject

{

public int money = 90 ;

public void WithDraw( int money )

{

this.money -= money;

OnWithDrawEvent(new UserMsgInfoEventArgs(string.Format("取走{0}钱,还有{1}钱", money, this.money)));

}

}

class UserMsgInfoEventArgs : EventArgs

{

//传送信息

public string sendinfo;

public UserMsgInfoEventArgs(string info)

{

this.sendinfo = info;

}

}

class Email

{

public void Update(object sender, UserMsgInfoEventArgs args)

{

Console.WriteLine( args.sendinfo );

}

}

}