定义一个高层接口，为子系统中的一组接口提供一个一致的外观，从而简化了该子系统的使用。

package com.strife.pattern.facade;

/**
 * 外观模式
 *
 * @author mengzhenghao
 * @date 2022/5/30
 */
public class Facade {
    public static void main(String[] args) {
        HomeFacade homeFacade = new HomeFacade();
        homeFacade.watchMovie();
        System.out.println("----------------------------------");
        homeFacade.endMovie();
    }
}

class DVDPlayer {

    private static DVDPlayer instance = new DVDPlayer();

    public static DVDPlayer getInstance() {
        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 is paused");
    }
}

class Popcorn {

    private static Popcorn instance = new Popcorn();

    public static Popcorn getInstance() {
        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");
    }

}

class Projector {

    private static Projector instance = new Projector();

    public static Projector getInstance() {
        return instance;
    }

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

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

    public void tvMode() {
        System.out.println("Projector is in tv mode");
    }

    public void wideScreenMode() {
        System.out.println("Projector is in wide screen mode");
    }
}

class Screen {

    private static Screen instance = new Screen();

    public static Screen getInstance() {
        return instance;
    }

    public void up() {
        System.out.println("Screen is going up");
    }

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

class HomeFacade {

    private DVDPlayer dvdPlayer;
    private Popcorn popcorn;
    private Projector projector;
    private Screen screen;

    public HomeFacade() {
        this.dvdPlayer = DVDPlayer.getInstance();
        this.popcorn = Popcorn.getInstance();
        this.projector = Projector.getInstance();
        this.screen = Screen.getInstance();
    }

    public void watchMovie() {
        popcorn.on();
        popcorn.pop();
        dvdPlayer.on();
        dvdPlayer.play();
        screen.down();
        projector.on();
        projector.tvMode();
    }

    public void endMovie() {
        popcorn.off();
        dvdPlayer.off();
        screen.up();
        projector.off();
    }
}