Java 计算两个日期直接相差多少天

public static int getBetweenDay(Date date1, Date date2) {        Calendar d1 = new GregorianCalendar();        d1.setTime(date1);        Calendar d2 = new GregorianCalendar();        d2.setTime(date2);        int days = d2.get(Calendar.DAY_OF_YEAR) - d1.get(Calendar.DAY_OF_YEAR);        System.out.println("days=" + days);        int y2 = d2.get(Calendar.YEAR);        if (d1.get(Calendar.YEAR) != y2) {            do {                days += d1.getActualMaximum(Calendar.DAY_OF_YEAR);                d1.add(Calendar.YEAR, 1);            } while (d1.get(Calendar.YEAR) != y2);        }        return days;    }