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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