结构型-Facade模式

package facade;
/**
 * @author jiq
 * 类型：Structural
 * 定义：外观模式(Facade)提供一个统一的接口，用来访问子系统中的一群接口。外观
 * 		定义了一个高层接口，使得子系统更容易使用。
 * 
 * OO原则：最少知识原则 --- 只和你的密友交谈。
 *
 * 区别： 装饰器模式包装一个对象，并提供额外的行为。
 * 		  适配器模式包装一个对象，并转换成不同的接口(接口改变)。
 * 		  外观模式包装许多对象，以简化他们的接口(接口改变)。
 * 		  代理模式包装一个对象，并控制它的访问(不改变被代理对象的接口)。
 */
//屏幕
class Screen {
	String description;
	public Screen(String description) {
		this.description = description;
	} 
	public void up() { /*...*/ } 
	public void down() { /*...*/ }
}
//DVD播放器
class DvdPlayer {
	String description;
	int currentTrack;
	Projector projector;
	String title;
	public DvdPlayer(String description, Projector projector) {
		this.description = description;
		this.projector = projector;
	}
	public void on() { /*...*/ } 
	public void off() { /*...*/ }
	public void eject() { /*...*/ } 
	public void play(String title) { /*...*/ }
	public void stop() { /*...*/ } 
	public void pause() { /*...*/ }
}
//投影仪
class Projector {
	String description;
	DvdPlayer cd;	
	public Projector(String description) {
		this.description = description;
	}
	public void on() { /*...*/ } 
	public void off() { /*...*/ } 
	public void setStereoSound() { /*...*/ } 
	public void setSurroundSound() { /*...*/ } 
	public void setVolume(int level) { /*...*/ } 
	public void setCd(DvdPlayer cd) { /*...*/ }
}

//家庭影院(外观)
class HomeTheaterFacade {
	Projector projector;
	DvdPlayer cd;
	Screen screen;
 
	public HomeTheaterFacade(Projector amp,DvdPlayer cd,Screen screen) {
		this.projector = amp;
		this.cd = cd;
		this.screen = screen;
	}
	//开始看电影(将一群接口封装为一个简洁的接口)
	public void watchMovie(String movie) {
		System.out.println("Get ready to watch a movie...");
		screen.down();
		projector.on();
		projector.setSurroundSound();
		projector.setVolume(5);
	}
	//结束看电影(将一群接口封装为一个简洁的接口)
	public void endMovie() {
		System.out.println("Shutting movie theater down...");
		screen.up();
		projector.off();
	}
}

public class FacadeTest {
	public static void main(String[] args) {
		Projector projector = new Projector("Top-O-Line Amplifier");
		DvdPlayer cd = new DvdPlayer("Top-O-Line CD Player",projector);
		Screen screen = new Screen("Theater Screen");
		HomeTheaterFacade homeTheater = new HomeTheaterFacade(projector,cd,screen);
		homeTheater.watchMovie("Raiders of the Lost Ark");
		homeTheater.endMovie();
	}
}