java获得指定时间几天前或几天后的日期

/**
	 * 得到几天前的时间
	 * 
	 * @param d
	 * @param day
	 * @return
	 */
	public static Date getDateBefore(Date d, int day) {
		Calendar now = Calendar.getInstance();
		now.setTime(d);
		now.set(Calendar.DATE, now.get(Calendar.DATE) - day);
		return now.getTime();
	}

	/**
	 * 得到几天后的时间
	 * 
	 * @param d
	 * @param day
	 * @return
	 */
	public static Date getDateAfter(Date d, int day) {
		Calendar now = Calendar.getInstance();
		now.setTime(d);
		now.set(Calendar.DATE, now.get(Calendar.DATE) + day);
		return now.getTime();
	}