第二节：外观模式应用

一、传统方式解决影院管理说明

　　1、外观模式可以理解为转换一群接口，客户只要调用一个接口，而不用调用多个接口才能达到目的。比如：在 PC 删安装软件软件的时候经常有一键安装选项（省去选择安装目录、安装的组件等），还有就是手机的重启功能（把关机和启动合为一个操作）。

　　2、外观模式就是解决多个复杂接口带来的使用困难，起到简化用户操作的作用；

　　3、示意图说明：

　　

二、外观模式应用实例

　　1、家庭影院要求

　　2、使用外观模式来完成家庭影院项目

　　3、思路分析和图解（类图）

　　　　

　　4、代码实现

　　　　各个设备类：

public class DVDPlayer {

    //使用单例模，饿汉式
    private static DVDPlayer instance = new DVDPlayer();

    private DVDPlayer() {}

    public static DVDPlayer getInstance() {
        return instance;
    }

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

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

    public void play() {
        System.out.println("DVD 正在播放");
    }

    public void pause() {
        System.out.println("DVD 暂定");
    }

}
---------------------------------------------------
/**
 * 爆米花机
 */
public class Popcorn {
    private static Popcorn instance = new Popcorn();

    private Popcorn() {}

    public static Popcorn getInstance() {
        return instance;
    }

    public void on() {
        System.out.println("打开爆米花机");
    }

    public void off() {
        System.out.println("关闭爆米花机");
    }

    public void pop() {
        System.out.println("爆米花ing");
    }

}
---------------------------------------------------
/**
 * 投影仪
 */
public class Projector {
    private static Projector instance = new Projector();

    private Projector() {}

    public static Projector getInstance() {
        return instance;
    }

    public void on() {
        System.out.println("打开投影仪");
    }

    public void off() {
        System.out.println("关闭投影仪");
    }

    public void focus() {
        System.out.println("投影仪聚焦");
    }
}
---------------------------------------------------
/**
 * 屏幕
 */
public class Screen {

    private static Screen instance = new Screen();

    private Screen() {}

    public static Screen getInstance() {
        return instance;
    }

    public void down() {
        System.out.println("放下屏幕");
    }

    public void up() {
        System.out.println("收起屏幕");
    }

}
---------------------------------------------------
/**
 * 立体声
 */
public class Stereo {
    private static Stereo instance = new Stereo();

    private Stereo() {}

    public static Stereo getInstance() {
        return instance;
    }

    public void on() {
        System.out.println("打开音响");
    }

    public void off() {
        System.out.println("关闭音响");
    }
    public void up() {
        System.out.println("调高音量");
    }

    public void down() {
        System.out.println("调低音量");
    }

}
---------------------------------------------------
/**
 * 灯光
 */
public class TheaterLight {
    private static TheaterLight instance = new TheaterLight();

    private TheaterLight() {}

    public static TheaterLight getInstance() {
        return instance;
    }

    public void on() {
        System.out.println("打开灯光");
    }

    public void off() {
        System.out.println("关闭灯光");
    }
    public void dim() {
        System.out.println("调暗灯光");
    }
    public void bright() {
        System.out.println("调亮灯光");
    }
}
---------------------------------------------------

　　家庭影院外观类：

/**
 * 家庭影院
 */
public class HomeTheaterFacade {

    //定义各个子系统对象
    private TheaterLight theaterLight; //灯光
    private Popcorn popcorn; //爆米花机
    private Stereo stereo; //音响
    private Projector projector; //投影仪
    private Screen screen;   //屏幕
    private DVDPlayer dvdPlayer; //dvd

    //构造器
    public HomeTheaterFacade() {
        this.theaterLight = TheaterLight.getInstance();
        this.popcorn = Popcorn.getInstance();
        this.stereo = Stereo.getInstance();
        this.projector = Projector.getInstance();
        this.screen = Screen.getInstance();
        this.dvdPlayer = DVDPlayer.getInstance();
    }

    //操作分成4步
    public void ready() {
        popcorn.on();
        popcorn.pop();
        screen.down();
        projector.on();
        stereo.on();
        dvdPlayer.on();
        theaterLight.on();
        theaterLight.dim();
    }

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

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

    public void end() {
        popcorn.off();
        theaterLight.bright();
        screen.up();
        projector.off();
        stereo.off();
        dvdPlayer.off();
    }

}

　　客户端：

public class Client {
    public static void main(String[] args) {
        //直接调用各个设备，很麻烦，不利于扩展


        //统一调用
        HomeTheaterFacade homeTheaterFacade = new HomeTheaterFacade();
        homeTheaterFacade.ready();
        homeTheaterFacade.play();

        System.out.println("----------");
        homeTheaterFacade.pause();
        System.out.println("----------");
        homeTheaterFacade.end();

    }
}