感觉有点政治的味道.当然.我们并不讨论政治.只是在说明很多情况下都必须进行的一种措施
事实上.当你并不想为每一个子系统建立独立的操作的时候.你也许更加希望能够有一个单一
的操作方案可供选择.那要不必为每个子系统都寻求其特有的操作方案.使操作变的单一.Facde
就可以做到这一点.
假设你有三个播音设备.分别使CD 磁带机,Mp3 它们分别有自己独立的操作放案.这让你很头痛
因为你必须掌握三套类似却有相对独立的方案.那么我们考虑如何解决
class CDPlay{ private string SongName; CDPlay(string sn){ SongName=sn; }
public void PlayCd(){ Console.WriteLine("Play Cd" + SongName); } public void StopCd(){ Console.WriteLine("Stop Cd"); }
}
class RecordPlay{ private string SongName; RecordPlay(string sn){ SongName=sn; }
public void PlayRecord(){ Console.WriteLine("Play Record" + SongName); } public void StopRecordd(){ Console.WriteLine("Stop Record"); } }
class Mp3Play{ private string SongName; CDPlay(string sn){ SongName=sn; }
public void PlayMp3(){ Console.WriteLine("Play Mp3" + SongName); } public void StopMp3(){ Console.WriteLine("Stop Mp3"); } }
//下面我们建立统一的界面
class Facade { private Mp3Play mp3; private RecordPlay rp; private CDPlay cd; private string playName; private string songName;
public string PlayName{ get{return playName;}; set{playName=value;}; } public string SongName{ get{return SongName;}; set{SongName=value;}; }
public Facade(string pn,string sn){ playName=pn; songName=sn; } public void play(){ switch(playName){ case "CD": Cd=new CDPlay(songName); Cd.PlayCd(); case "mp3": mp3=new Mp3Play(songName); mp3.PlayMp3(); case "Record": rd=new RecordPlay(songName); rd.PlayRecord(); } } public void stop(){ case "CD": Cd=new CDPlay(songName); Cd.stopCd(); case "mp3": mp3=new Mp3Play(songName); mp3.stopMp3(); case "Record": rd=new RecordPlay(songName); rd.stopRecord(); } }
//调用
public class Client { public static int Main(string[] args) { Facade facade = new Facade("CD"); facade.play(); facade.Stop();
facade.PlayName="mp3"; facade.play(); facade.Stop();
facade.PlayName="Record"; facade.play(); facade.Stop(); return 0; } }
这样我们只需要一个统一的界面.而不需要知道其每个子系统是如何特别定制的. 
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