设计模式8-外观模式-优快云博客

本文链接：https://blog.youkuaiyun.com/bobshute/article/details/99662997

本文通过家庭影院系统的具体实现，深入解析了外观模式的设计原理及其应用优势。通过将复杂系统的多个子系统封装到一个统一的接口中，外观模式简化了系统的使用，实现了功能解耦，提升了系统的可维护性和易用性。

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1.场景问题解决

1.1 场景描述

1.2 OO设计

1.3 需求变动

1.4 带来问题

2.用设计模式改进

2.1 分析

2.2 重新设计

Popcorn,Screen,Projector,DVDPlayer

//爆米花
public class Popcorn {

	private static Popcorn instance = null;

	private Popcorn() {
	}

	public static Popcorn getInstance() {
		if (instance == null) {
			instance = new Popcorn();
		}
		return instance;
	}
	
	public void on() {
		System.out.println("Popcorn On");
	}

	public void off() {
		System.out.println("Popcorn Off");
	}

	public void pop() {
		System.out.println("Popcorn is popping");
	}


	public static class Stereo {

        private static Stereo instance = null;
        private int volume = 5;

        private Stereo() {
        }

        public static Stereo getInstance() {
            if (instance == null) {
                instance = new Stereo();
            }
            return instance;
        }

        public void on() {
            System.out.println("Stereo On");
        }

        public void off() {
            System.out.println("Stereo Off");
        }

        public void setVolume(int vol) {
            volume = vol;
            System.out.println("the volume of Stereo is set to  " + volume);
        }

        public void addVolume() {
            if (volume < 11) {
                volume++;
                setVolume(volume);
            }
        }

        public void subVolume() {
            if (volume > 0) {
                volume--;
                setVolume(volume);
            }
        }
    }

	public static class TheaterLights {

        private static TheaterLights instance = null;

        private TheaterLights() {
        }

        public static TheaterLights getInstance() {
            if (instance == null) {
                instance = new TheaterLights();
            }
            return instance;
        }

        public void on() {
            System.out.println("TheaterLights On");
        }

        public void off() {
            System.out.println("TheaterLights Off");
        }

        public void dim(int d) {
            System.out.println("TheaterLights dim to " + d + "%");
        }

        public void bright() {
            dim(100);
            System.out.println("TheaterLights bright");
        }
    }
}




//投影屏幕
public class Screen {

	private static Screen instance = null;

	private Screen() {
	}

	public static Screen getInstance() {
		if (instance == null) {
			instance = new Screen();
		}
		return instance;
	}
	
	public void up() {
		System.out.println("Screen  up");
	}

	public void down() {
		System.out.println("Screen  down");
	}
}




//投影仪
public class Projector {
	private int size=5;

	private static Projector instance = null;

	private Projector() {
	}

	public static Projector getInstance() {
		if (instance == null) {
			instance = new Projector();
		}
		return instance;
	}
	
	public void on() {
		System.out.println("Projector On");
	}

	public void off() {
		System.out.println("Projector Off");
	}

	public void focus() {
		System.out.println("Popcorn is focus");
	}
	
	public void zoom(int size) {
		this.size=size;
		System.out.println("Popcorn zoom to"+size);
	}
}



public class DVDPlayer {
	private static DVDPlayer instance = null;
	private DVDPlayer() {
	}

	public static DVDPlayer getInstance() {
		if (instance == null) {
			instance = new DVDPlayer();
		}
		return instance;
	}
	
	public void on() {
		System.out.println("DVDPlayer On");
	}

	public void off() {
		System.out.println("DVDPlayer Off");
	}

	public void play() {
		System.out.println("DVDPlayer is playing");
	}
	
	public void pause() {
		System.out.println("DVDPlayer  pause");
	}
	
	public void setdvd() {
		System.out.println("DVDPlayer  is setting dvd");
	}
}

HomeTheaterFacade

public class HomeTheaterFacade {
	private Popcorn.TheaterLights mTheaterLights;
	private Popcorn mPopcorn;
	private Popcorn.Stereo mStereo;
	private Projector mProjector;
	private Screen mScreen;
	private DVDPlayer mDVDPlayer;

	public HomeTheaterFacade() {
		mTheaterLights = Popcorn.TheaterLights.getInstance();
		mPopcorn = Popcorn.getInstance();
		mStereo = Popcorn.Stereo.getInstance();
		mProjector = Projector.getInstance();
		mScreen = Screen.getInstance();
		mDVDPlayer = DVDPlayer.getInstance();
	}

	public void ready() {
		mPopcorn.on();
		mPopcorn.pop();
		mScreen.down();
		mProjector.on();
		mStereo.on();
		mDVDPlayer.on();
		mDVDPlayer.setdvd();
		mTheaterLights.dim(10);
	}

	public void end() {
		mPopcorn.off();
		mTheaterLights.bright();
		mScreen.up();
		mProjector.off();
		mStereo.off();
		mDVDPlayer.setdvd();
		mDVDPlayer.off();
	}

	public void play() {
		mDVDPlayer.play();
	}

	public void pause() {
		mDVDPlayer.pause();
	}
}

FacadeTest 测试类

public class FacadeTest {
	public static void main(String[] args) {
		HomeTheaterFacade mHomeTheaterFacade=new HomeTheaterFacade();
		
		mHomeTheaterFacade.ready();
		mHomeTheaterFacade.play();
	}
}