[디자인패턴] 커멘드 패턴, command pattern

http://ko.wikipedia.org/wiki/%EC%BB%A4%EB%A7%A8%EB%93%9C_%ED%8C%A8%ED%84%B4

커맨드 패턴을 이용하면 요구사항을 객체로 캡슐화 할 수 있다. 매개변수를 써서 여러가지 요구사항을 만들 수도 있다. 또한 요청내역을 큐에 저장하여 로그를 기록하는 것도 가능하고 작업 취소 구현도 가능하다.

/*the Invoker class*/
public class Switch {
    private Command flipUpCommand;
    private Command flipDownCommand;
 
    public Switch(Command flipUpCmd,Command flipDownCmd){
            this.flipUpCommand=flipUpCmd;
            this.flipDownCommand=flipDownCmd;
           }
 
    public void flipUp(){
         flipUpCommand.execute();
    }
 
    public void flipDown(){
         flipDownCommand.execute();
    }
}
 
/*Receiver class*/
 
public class Light{
     public Light(){  }
 
     public void turnOn(){
        System.out.println("The light is on");
     }
 
     public void turnOff(){
        System.out.println("The light is off");
     }
}
 
 
/*the Command interface*/
 
public interface Command{
    void execute();
}
 
 
/*the Command for turning on the light*/
 
public class TurnOnLightCommand implements Command{
   private Light theLight;
 
   public TurnOnLightCommand(Light light){
        this.theLight=light;
       }
 
   public void execute(){
      theLight.turnOn();
   }
}
 
/*the Command for turning off the light*/
 
public class TurnOffLightCommand implements Command{
   private Light theLight;
 
   public TurnOffLightCommand(Light light){
        this.theLight=light;
       }
 
   public void execute(){
      theLight.turnOff();
   }
}
 
/*The test class*/
public class TestCommand{
   public static void main(String[] args){
       Light light=new Light();
       Command switchUp=new TurnOnLightCommand(light);
       Command switchDown=new TurnOffLightCommand(light);
 
       Switch s=new Switch(switchUp,switchDown);
 
       s.flipUp();
       s.flipDown();
   }
}