时间处理——计算日差间隔

经常会有一些需求，要求检查两个日期之间相隔的天数。方便起见就写成一个静态函数，并且不区分前后日期，使用绝对值。

/**
     * 获取两个日期的相差天数（自然日）只计算日期，所以清除时分秒
     */
    public static Long getDaysBetween(Date startDate, Date endDate) {
        Calendar fromCalendar = Calendar.getInstance();
        fromCalendar.setTime(startDate);
        fromCalendar.set(Calendar.HOUR_OF_DAY, 0);
        fromCalendar.set(Calendar.MINUTE, 0);
        fromCalendar.set(Calendar.SECOND, 0);
        fromCalendar.set(Calendar.MILLISECOND, 0);

        Calendar toCalendar = Calendar.getInstance();
        toCalendar.setTime(endDate);
        toCalendar.set(Calendar.HOUR_OF_DAY, 0);
        toCalendar.set(Calendar.MINUTE, 0);
        toCalendar.set(Calendar.SECOND, 0);
        toCalendar.set(Calendar.MILLISECOND, 0);

        Long DaysBetween = (toCalendar.getTime().getTime() - fromCalendar.getTime().getTime()) / (1000 * 60 * 60 * 24);
        return Math.abs(DaysBetween);
    }