비망록 디자인 모드

/**
 *      
 */
public class Originator {

    private String state;

    /**
     *               
     */
    public MementoIF createMemento() {
        return new Memento(this.state);
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
        System.out.println("Current state is " + this.state);
    }

    /**
     *                  
     */
    public void restoreMemento(MementoIF memento) {
        Memento aMemento = (Memento) memento;
        this.setState(aMemento.getSavedState());
    }

    /**
     *      ,   
     */
    protected class Memento implements MementoIF {
        private String savedState;

        public Memento(String someState) {
            this.savedState = someState;
        }

        public String getSavedState() {
            return savedState;
        }

        public void setSavedState(String savedState) {
            this.savedState = savedState;
        }
    }
}

public interface MementoIF {

}

/**
 *      
 */
public class Caretaker {

    private MementoIF memento;
    /**
     *         
     */
    public MementoIF retrieveMemento() {
        return this.memento;
    }
    /**
     *         
     */
    public void saveMemento(MementoIF memento) {
        this.memento = memento;
    }
}

public class Client {
    //   
    private static Originator originator = new Originator();
    //   
    private static Caretaker caretaker = new Caretaker();

    public static void main(String[] args) {
        //         
        originator.setState("ON");
        //                
        caretaker.saveMemento(originator.createMemento());
        //         
        originator.setState("OFF");
        //         
        originator.restoreMemento(caretaker.retrieveMemento());
    }
}