如何获得从现在到未来时间的月，周，日和小时数？

我需要找出使用Java从现在到未来时间的剩余月数，周数，天数和小时数。我不能使用像Joda这样的任何第三方库。我怎么能只使用JDK类呢？

I need to find out the number of months, weeks, days and hours left from now to a future time using Java. I can not use any third party library like Joda. How can I do that using just JDK classes?

到目前为止，这是我想出的。除了某些情况外，它有用：

So far, this is what I have come up with. It sort of works, except for some situations:

public class DateUtil {

public static Integer[] components(Date from, Date to) {
    Integer[] result = new Integer[4];
    //SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");
    //df.setTimeZone(TimeZone.getTimeZone("EST"));

    Calendar fromCal = new GregorianCalendar();
    Calendar toCal = new GregorianCalendar();

    fromCal.setTime(from);
    toCal.setTime(to);

    int months = 0;
    do {
        fromCal.add(Calendar.MONTH, 1);
        ++months;
        //System.out.println(df.format(fromCal.getTime()));
    } while (fromCal.before(toCal));

    fromCal.add(Calendar.MONTH, -1);
    --months;

    int days = 0;
    do {
        fromCal.add(Calendar.DAY_OF_YEAR, 1);
        ++days;
    } while (fromCal.before(toCal));

    fromCal.add(Calendar.DAY_OF_YEAR, -1);
    --days;

    int hours = 0;
    do {
        fromCal.add(Calendar.HOUR_OF_DAY, 1);
        ++hours;
    } while (fromCal.before(toCal));

    fromCal.add(Calendar.HOUR_OF_DAY, -1);
    --hours;

    int minutes = 0;
    do {
        fromCal.add(Calendar.MINUTE, 1);
        ++minutes;
    } while (fromCal.before(toCal));

    result[0] = months;
    result[1] = days;
    result[2] = hours;
    result[3] = minutes;

    return result;
}

public static void main(String[] args) {
    try {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");
        df.setTimeZone(TimeZone.getTimeZone("EST"));

        Date from = df.parse("2014-03-29 00:00");
        Date to = df.parse("2014-05-29 00:00");
        Integer result[] = components(from, to);

        System.out.printf("Months:%02d Days:%02d Hrs:%02d Mins:%02d\n", 
                result[0], result[1], result[2], result[3]);
    } catch (Exception e) {
        e.printStackTrace();
    }
}
}

当你出现不可接受的结果时2月在中间，开始日期是月末。例如：

It produces unacceptable results when you have February in the middle and start date is end of the month. For example:

来自：2013年12月31日
到：2014年12月31日

From: Dec 31, 2013 To: Dec 31, 2014

差异将产生：12个月，3天。

The difference will produce: 12 months, 3 days.