手寫一個監聽器

1.事件對象

public class Even {

    private Robot robot;

    public Even() {
        super();
    }

    public Even(Robot robot) {
        super();
        this.robot = robot;
    }


    public Robot getRobot() {
        return robot;
    }

    public void setRobot(Robot robot) {
        this.robot = robot;
    }
}

2.事件源：機器人 

public class Robot {

    private RobotListener listener;

    /**
     * 註冊機器人監聽器
     *
     * @param listener
     */
    public void registerListener(RobotListener listener) {
        this.listener = listener;
    }

    /**
     * 工作
     */
    public void working() {
        if (listener != null) {
            Even even = new Even(this);
            this.listener.working(even);
        }
        System.out.println("機器人開始工作......");
    }

    /**
     * 跳舞
     */
    public void dancing() {
        if (listener != null) {
            Even even = new Even(this);
            this.listener.dancing(even);
        }
        System.out.println("機器人開始跳舞......");
    }
}

3.事件監聽器

public interface RobotListener {

    void working(Even even);

    void dancing(Even even);
}

4.自定義監聽器

public class MyRobotListener implements RobotListener {

    @Override
    public void working(Even even) {
        Robot robot = even.getRobot();
        System.out.println("機器人工作提示：請看管好的你機器人，防止它偷懶！");
    }

    @Override
    public void dancing(Even even) {
        Robot robot = even.getRobot();
        System.out.println("機器人跳舞提示：機器人跳舞動作優美，請不要走神哦！");
    }
}

5.測試類

public class TestListener {

    public static void main(String[] args) {
        Robot robot = new Robot();
        robot.registerListener(new MyRobotListener());
        robot.working();
        robot.dancing();
    }
}