행위패턴 : State 패턴

분류 : 행위패턴(Behavioral Patterns)

정의 :

객체의 상태에 따라 동일 루틴에서 다른 행동을 하는 패턴

용도 :

소스

interface Statelike {
	 
    /**
     * Writer method for the state name.
     * @param STATE_CONTEXT
     * @param NAME
     */
    void writeName(final StateContext STATE_CONTEXT, final String NAME);
 
}


public class StateA implements Statelike {
	/** (non-Javadoc)
     * @see state.Statelike#writeName(state.StateContext, java.lang.String)
     */
    @Override
    public void writeName(final StateContext STATE_CONTEXT, final String NAME) {
        System.out.println(NAME.toLowerCase());
        STATE_CONTEXT.setState(new StateB());
    }
}



public class StateB implements Statelike {
	/** State counter */
    private int count = 0;
 
    /** (non-Javadoc)
     * @see state.Statelike#writeName(state.StateContext, java.lang.String)
     */
    @Override
    public void writeName(final StateContext STATE_CONTEXT, final String NAME) {
        System.out.println(NAME.toUpperCase());
        // Change state after StateB's writeName() gets invoked twice
        if(++count > 1) {
            STATE_CONTEXT.setState(new StateA());
        }
    }
}


public class StateContext {
	private Statelike myState;
    /**
     * Standard constructor
     */
	public StateContext() {
	    setState(new StateA());
	}
	
	    /**
	     * Setter method for the state.
	     * Normally only called by classes implementing the State interface.
	     * @param NEW_STATE
	     */
	public void setState(final Statelike NEW_STATE) {
	    myState = NEW_STATE;
	}
	
	    /**
	     * Writer method
	     * @param NAME
	     */
	public void writeName(final String NAME) {
	    myState.writeName(this, NAME);
	}
}


public class TestClientState {
	public static void main(String[] args) {
        final StateContext SC = new StateContext();
 
        SC.writeName("Monday");
        SC.writeName("Tuesday");
        SC.writeName("Wednesday");
        SC.writeName("Thursday");
        SC.writeName("Friday");
        SC.writeName("Saturday");
        SC.writeName("Sunday");
    }
}

참고자료

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