Java设计模式之外观模式示例详解

来源：jb51　　时间：2022/3/2 17:43:47　　对本文有异议

定义

外观模式为多个复杂的子系统，提供了一个一致的界面，使得调用端只和这个接口发生调用，而无须关系这个子系统内部的细节

案例

需求

看电影的时候需要进行一系列的操作，比如打开播放器，放下屏幕，打开投影仪，打开音响等，这个要怎么进行管理呢

方案：外观模式实现

定义播放器类

public class Player {
 
    private static Player player = new Player();
 
    private Player(){}
 
    public static Player getInstance(){
 
        return player;
    }
 
    public void on(){
        System.out.println("打开播放器");
    }
 
    public void off(){
        System.out.println("关闭播放器");
    }
 
    public void play(){
        System.out.println("使用播放器播放电影");
    }
 
    public void pause(){
        System.out.println("暂停播放器");
    }
 
    public void select(){
        System.out.println("选择喜欢的电影");
    }
}

定义投影仪类

public class Projector {
 
    private static Projector projector = new Projector();
 
    private Projector(){}
 
    public static Projector getInstance(){
 
        return projector;
    }
 
    public void on(){
        System.out.println("放下屏幕，打开投影仪");
    }
 
    public void off(){
        System.out.println("关闭投影仪");
    }
 
    public void focus(){
        System.out.println("调节投影仪焦距");
    }
 
    public void zoom(){
        System.out.println("投影仪变焦");
    }
 
}

定义音响类

public class Stereo {
 
    private static Stereo stereo = new Stereo();
 
    private Stereo(){}
 
    public static Stereo getInstance(){
        return stereo;
    }
 
    public void on(){
        System.out.println("打开音响");
    }
 
    public void off(){
        System.out.println("关闭音响");
    }
 
    public void setVolume(){
        System.out.println("调节音响音量");
    }
}

定义爆米花机类

/**
 * 爆米花机
 * @author:liyajie
 * @createTime:2022/3/2 14:24
 * @version:1.0
 */
public class Popcorn {
 
    private static Popcorn popcorn = new Popcorn();
 
    private Popcorn(){}
 
    public static Popcorn getInstance(){
        return popcorn;
    }
 
    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("制作爆米花");
    }
}

定义家庭影院外观类

public class HomeTheaterFacade {
 
    // 聚合各个子系统
    private Player player;
 
    private Popcorn popcorn;
 
    private Projector projector;
 
    private Stereo stereo;
 
    public HomeTheaterFacade(){
 
    }
 
    // 全参构造器
    public HomeTheaterFacade(Player player, Popcorn popcorn,Projector projector,Stereo stereo){
        this.player = player;
        this.popcorn = popcorn;
        this.projector = projector;
        this.stereo = stereo;
    }
 
    // 准备阶段
    public void ready(){
        popcorn.on();
        player.on();
        projector.on();
        stereo.on();
    }
 
    // 播放
    public void play(){
        player.select();
        popcorn.pop();
        projector.focus();
        stereo.setVolume();
    }
 
    // 结束
    public void end(){
        player.off();
        popcorn.off();
        projector.off();
        stereo.off();
    }
}

定义测试类

public class Test {
    public static void main(String[] args) {
        HomeTheaterFacade homeTheaterFacade = new HomeTheaterFacade(Player.getInstance(),Popcorn.getInstance(),Projector.getInstance(),Stereo.getInstance());
        homeTheaterFacade.ready();
        homeTheaterFacade.play();
        homeTheaterFacade.end();
    }
}