door_1.java

本书透彻讲解了经典的《设计模式：可复用面向对象软件的基础》一书涵盖的23种基本设计模式。本书将这些设计模式分成五类：接口型模式、责任型模式、构造型模式、操作型模式

package com.oozinoz.carousel;

import java.util.*;



/*
 * Copyright (c) 2001 Steven J. Metsker.
 * 
 * Steve Metsker makes no representations or warranties about
 * the fitness of this software for any particular purpose, 
 * including the implied warranty of merchantability.
 *
 * Please use this software as you wish with the sole
 * restriction that you may not claim that you wrote it.
 */
/**
 * This class provides an initial model of a carousel door
 * that manages its state without moving state-specific
 * logic out to state classes.
 * 
 * @author Steven J. Metsker
 */
public class Door_1 extends Observable 
{
	public static final int CLOSED   = -1;
	public static final int CLOSING  = -4;
	public static final int OPEN     = -3;
	public static final int OPENING  = -2;
	//
	private int state = CLOSED;
	public static final int STAYOPEN = -5;

/**
 * The carousel user has clicked the carousel button. This "one
 * touch" button elicits different behaviors, depending on the
 * state of the door.
 */
public void click()
{
	if (state == CLOSED)
	{
		setState(OPENING);
	}
	else if (state == OPENING || state == STAYOPEN)
	{
		setState(CLOSING);
	}
	else if (state == OPEN)
	{
		setState(STAYOPEN);
	}
	else if (state == CLOSING)
	{
		setState(OPENING);
	}
}

/**
 * This is a notification from the mechanical carousel that the
 * door finished opening or shutting.
 */
public void complete()
{
	if (state == OPENING)
	{
		setState(OPEN);
	}
	else if (state == CLOSING)
	{
		setState(CLOSED);
	}
}

private void setState(int state)
{
	this.state = state;
	setChanged();
	notifyObservers();
}

/**
 * Return a textual description of the door's state.
 *
 * @return a textual description of the door's state
 */
public String status()
{
	switch (state)
	{
		case OPENING :
			return "Opening";
		case OPEN :
			return "Open";
		case CLOSING :
			return "Closing";
		case STAYOPEN :
			return "StayOpen";
		default :
			return "Closed";
	}
}

/**
 * This is a notification from the mechanical carousel that the
 * door got tired of being open.
 */
public void timeout()
{
	setState(CLOSING);
}
}