Facade模式

Facade 客户端可以调用这个角色的方法。此角色知晓相关的(一个或者多个)子系统的功能和责任。在正常情况下，本角色会将所有从客户端发来的请求委派到相应的子系统去。

subsystem 可以同时有一个或者多个子系统。每一个子系统都不是一个单独的类，而是一个类的集合。每一个子系统都可以被客户端直接调用，或者被门面角色调用。子系统并不知道门面的存在，对于子系统而言，门面仅仅是另外一个客户端而已。

public class Camera {
  public void TurnOn() {
    System.out.println("Turning on the camera.");
  }

  public void TurnOff() {
    System.out.println("Turning off the camera.");
  }

  public void Rotate(int degrees) {
    System.out.println("Rotating the camera by {0} degrees.", degrees);
  }
}

public class Light {
  public void TurnOff() {
    System.out.println("Turning on the light.");
  }

  public void TurnOn() {
    System.out.println("Turning off the light.");
  }

  public void ChangeBulb() {
    System.out.println("changing the light-bulb.");
  }
}

public class Sensor {
  public void Activate() {
    System.out.println("Activating the sensor.");
  }

  public void Deactivate() {
    System.out.println("Deactivating the sensor.");
  }

  public void Trigger() {
    System.out.println("The sensor has triggered.");
  }
}

public class Alarm {
  public void Activate() {
    System.out.println("Activating the alarm.");
  }

  public void Deactivate() {
    System.out.println("Deactivating the alarm.");
  }

  public void Ring() {
    System.out.println("Ringing the alarm.");
  }

  public void StopRing() {
    System.out.println("Stop the alarm.");
  }
}

public class SecurityFacade {
  private static Camera camera1, camera2;
  private static Light light1, light2, light3;
  private static Sensor sensor;
  private static Alarm alarm;

  static SecurityFacade() {
    camera1 = new Camera();
    camera2 = new Camera();
    light1 = new Light();
    light2 = new Light();
    light3 = new Light();
    sensor = new Sensor();
    alarm = new Alarm();
  }
 
  public void Activate() {
    camera1.TurnOn();
    camera2.TurnOn();
    light1.TurnOn();
    light2.TurnOn();
    light3.TurnOn();
    sensor.Activate();
    alarm.Activate();
  }

  public void Deactivate() {
    camera1.TurnOff();
    camera2.TurnOff();
    light1.TurnOff();
    light2.TurnOff();
    light3.TurnOff();
    sensor.Deactivate();
    alarm.Deactivate();
  }
}

public class Client {
  private static SecurityFacade security;

  public static void Main( string[] args )
  {
    security = new SecurityFacade();
    security.Activate();
    System.out.println("/n--------------------/n");
    security.Deactivate();
  }
}