java计算两个日期相差多少天

java计算两个日期相差多少天

public class DateUtil{
	public static int betweenDays(Date startDate, Date endDate ) throws Exception {
		Calendar beginCalendar = Calendar.getInstance();
		Calendar endCalendar = Calendar.getInstance() ; 

		try {
			beginCalendar.setTime( startDate ) ;
			endCalendar.setTime( endDate ) ;

			if (beginCalendar.get(Calendar.YEAR) == endCalendar.get(Calendar.YEAR)) {
				return endCalendar.get(Calendar.DAY_OF_YEAR)
						- beginCalendar.get(Calendar.DAY_OF_YEAR);
			} else {
				if (beginCalendar.getTimeInMillis() < endCalendar.getTimeInMillis()) {
					int days = beginCalendar.getActualMaximum(Calendar.DAY_OF_YEAR)
							- beginCalendar.get(Calendar.DAY_OF_YEAR)
							+ endCalendar.get(Calendar.DAY_OF_YEAR);
					for (int i = beginCalendar.get(Calendar.YEAR) + 1; i < endCalendar
							.get(Calendar.YEAR); i++) {
						Calendar c = Calendar.getInstance();
						c.set(Calendar.YEAR, i);
						days += c.getActualMaximum(Calendar.DAY_OF_YEAR);
					}
					return days;
				} else {
					int days =endCalendar.getActualMaximum(Calendar.DAY_OF_YEAR)
							- endCalendar.get(Calendar.DAY_OF_YEAR)
							+ beginCalendar.get(Calendar.DAY_OF_YEAR);
					for (int i = endCalendar.get(Calendar.YEAR) + 1; i < beginCalendar
							.get(Calendar.YEAR); i++) {
						Calendar c = Calendar.getInstance();
						c.set(Calendar.YEAR, i);
						days += c.getActualMaximum(Calendar.DAY_OF_YEAR);
					}
					return days;
				}
			}
		} catch (Exception e) {
			throw e;
		}
	}

}