设计模式之九外观模式

基本介绍

1) 外观模式（Facade），也叫“过程模式：外观模式为子系统中的一组接口提供 一个一致的界面，此模式定义了一个高层接口，这个接口使得这一子系统更加 容易使用

2) 外观模式通过定义一个一致的接口，用以屏蔽内部子系统的细节，使得调用端 只需跟这个接口发生调用，而无需关心这个子系统的内部细节

uml类图

 

案例介绍

组建一个家庭影院： DVD播放器、投影仪、自动屏幕、环绕立体声、爆米花机,要求完成使用家庭影院的 功能，其过程为： • 直接用遥控器：统筹各设备开关 • 开爆米花机 • 放下屏幕 • 开投影仪 • 开音响 • 开DVD，选dvd • 去拿爆米花 • 调暗灯光 • 播放 • 观影结束后，关闭各种设备

外观模式实现类图

 

 代码实现

package com.hy.facade;

public class DVDPlayer {
    

    private static DVDPlayer instance = new DVDPlayer();
    
    public static DVDPlayer getInstanc() {
        return instance;
    }
    
    public void on() {
        System.out.println(" dvd on ");
    }
    public void off() {
        System.out.println(" dvd off ");
    }
    
    public void play() {
        System.out.println(" dvd is playing ");
    }
    
    //....
    public void pause() {
        System.out.println(" dvd pause ..");
    }
}


package com.hy.facade;

public 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 ff ");
    }
    
    public void pop() {
        System.out.println(" popcorn is poping  ");
    }
}


package com.hy.facade;

public 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 ff ");
    }
    
    public void focus() {
        System.out.println(" Projector is Projector  ");
    }
    
    //...
}


package com.hy.facade;

public class Screen {

    private static Screen instance = new Screen();

    public static Screen getInstance() {
        return instance;
    }


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

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


}


package com.hy.facade;

public class Stereo {

    private static Stereo instance = new Stereo();

    public static Stereo getInstance() {
        return instance;
    }

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

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

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

    //...
}


package com.hy.facade;

public class TheaterLight {

    private static TheaterLight instance = new TheaterLight();

    public static TheaterLight getInstance() {
        return instance;
    }

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

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

    public void dim() {
        System.out.println(" TheaterLight dim.. ");
    }

    public void bright() {
        System.out.println(" TheaterLight bright.. ");
    }
}


package com.hy.facade;

public class HomeTheaterFacade {

    //定义各个子系统对象
    private TheaterLight theaterLight;
    private Popcorn popcorn;
    private Stereo stereo;
    private Projector projector;
    private Screen screen;
    private DVDPlayer dVDPlayer;


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

    //操作分成 4 步

    public void ready() {
        popcorn.on();
        popcorn.pop();
        screen.down();
        projector.on();
        stereo.on();
        dVDPlayer.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();
    }


}


package com.hy.facade;

public class Client {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
//这里直接调用。。 很麻烦
        HomeTheaterFacade homeTheaterFacade = new HomeTheaterFacade();
        homeTheaterFacade.ready();
        homeTheaterFacade.play();


        homeTheaterFacade.end();
    }

}