计算两个日期之间相差的天数

	/**
	 * 计算两个日期之间相差的天数
	 *
	 * @param smdate
	 *            较小的时间
	 * @param bdate
	 *            较大的时间
	 * @return 相差天数
	 * @throws ParseException
	 */
	public static int daysBetween(Date smdate, Date bdate) throws ParseException {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		smdate = sdf.parse(sdf.format(smdate));
		bdate = sdf.parse(sdf.format(bdate));
		Calendar cal = Calendar.getInstance();
		cal.setTime(smdate);
		long time1 = cal.getTimeInMillis();
		cal.setTime(bdate);
		long time2 = cal.getTimeInMillis();
		long between_days = (time2 - time1) / (1000 * 3600 * 24);

		return Integer.parseInt(String.valueOf(between_days));
	}