커맨드 패턴

1 개요

command pattern
커맨드 패턴

명령을 클래스로 표현하는 구조
요청을 객체의 형태로 캡슐화하는 디자인 패턴
서로 요청이 다른 사용자의 매개변수, 요청 저장, 로깅, 연산 취소를 지원한다.

2 예제

/* The Command interface */
public interface Command {
   void execute();
}
 
import java.util.List;
import java.util.ArrayList;
 
/* The Invoker class */
public class Switch {
   private List<Command> history = new ArrayList<Command>();
 
   public Switch() {
   }
 
   public void storeAndExecute(Command cmd) {
      this.history.add(cmd); // optional 
      cmd.execute();        
   }
}
 
/* The 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 for turning on the light - ConcreteCommand #1 */
public class FlipUpCommand implements Command {
   private Light theLight;
 
   public FlipUpCommand(Light light) {
      this.theLight = light;
   }
 
   public void execute(){
      theLight.turnOn();
   }
}
 
/* The Command for turning off the light - ConcreteCommand #2 */
public class FlipDownCommand implements Command {
   private Light theLight;
 
   public FlipDownCommand(Light light) {
      this.theLight = light;
   }
 
   public void execute() {
      theLight.turnOff();
   }
}
 
/* The test class or client */
public class PressSwitch {
   public static void main(String[] args){
      Light lamp = new Light();
      Command switchUp = new FlipUpCommand(lamp);
      Command switchDown = new FlipDownCommand(lamp);
 
      Switch s = new Switch();
 
      try {
         if (args[0].equalsIgnoreCase("ON")) {
            s.storeAndExecute(switchUp);
         }
         else if (args[0].equalsIgnoreCase("OFF")) {
            s.storeAndExecute(switchDown);
         }
         else {
            System.out.println("Argument \"ON\" or \"OFF\" is required.");
         }
      } catch (Exception e) {
         System.out.println("Arguments required.");
      }
   }
}

3 같이 보기

4 참고

http://en.wikipedia.org/wiki/Command_pattern