java 计算日期相差天数

 public static int getDayDiffer(Date startDate, Date endDate) throws ParseException {
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        long startDateTime = dateFormat.parse(dateFormat.format(startDate)).getTime();
        long endDateTime = dateFormat.parse(dateFormat.format(endDate)).getTime();
        return (int) ((endDateTime - startDateTime) / (1000 * 3600 * 24));
    }