如果你想修复跨越夏时制边界的日期范围的问题(例如，一个日期在夏季，另一个日期在冬季)，你可以使用这个来获得天数的差异:

public static long calculateDifferenceInDays(Date start, Date end, Locale locale) {
    Calendar cal = Calendar.getInstance(locale);

    cal.setTime(start);
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    cal.set(Calendar.MILLISECOND, 0);
    long startTime = cal.getTimeInMillis();

    cal.setTime(end);
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    cal.set(Calendar.MILLISECOND, 0);
    long endTime = cal.getTimeInMillis();

    // calculate the offset if one of the dates is in summer time and the other one in winter time
    TimeZone timezone = cal.getTimeZone();
    int offsetStart = timezone.getOffset(startTime);
    int offsetEnd = timezone.getOffset(endTime);
    int offset = offsetEnd - offsetStart;

    return TimeUnit.MILLISECONDS.toDays(endTime - startTime + offset);
}

public static void main(String[] args) {

    String dateStart = "01/14/2012 09:29:58";
    String dateStop = "01/14/2012 10:31:48";

    SimpleDateFormat format = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");

    Date d1 = null;
    Date d2 = null;

    try {
        d1 = format.parse(dateStart);
        d2 = format.parse(dateStop);

        DateTime date11 = new DateTime(d1);
        DateTime date22 = new DateTime(d2);
        int days = Days.daysBetween(date11.withTimeAtStartOfDay(), date22.withTimeAtStartOfDay()).getDays();
        int hours = Hours.hoursBetween(date11, date22).getHours() % 24;
        int minutes = Minutes.minutesBetween(date11, date22).getMinutes() % 60;
        int seconds = Seconds.secondsBetween(date11, date22).getSeconds() % 60;
        if (hours > 0 || minutes > 0 || seconds > 0) {
            days = days + 1;
        }

        System.out.println(days);

    } catch (Exception e) {
        e.printStackTrace();
    }

}

这将为同一天提供日期差异

另一个纯Java变体:

public boolean isWithin30Days(Calendar queryCalendar) {

    // 1. Take the date you are checking, and roll it back N days
    Calendar queryCalMinus30Days = Calendar.getInstance();
    queryCalMinus30Days.setTime(queryCalendar.getTime());
    queryCalMinus30Days.add(Calendar.DATE, -30); // subtract 30 days from the calendar

    // 2. Get respective milliseconds for the two Calendars: now & queryCal minus N days 
    long nowL = Calendar.getInstance().getTimeInMillis();
    long queryCalMinus30DaysL = queryCalMinus30Days.getTimeInMillis();

    // 3. if nowL is still less than the queryCalMinus30DaysL, it means queryCalendar is more than 30 days into future
    boolean isWithin30Days = nowL >= queryCalMinus30DaysL;

    return isWithin30Days;
}

感谢这里的入门代码:https://stackoverflow.com/a/30207726/2162226

不使用标准API，不行。你可以这样做:

class Duration {
    private final TimeUnit unit;
    private final long length;
    // ...
}

或者你可以使用Joda:

DateTime a = ..., b = ...;
Duration d = new Duration(a, b);

int daysDiff = (date1.getTime() - date2.getTime()) / MILLIS_PER_DAY;

不幸的是，JDK Date API被严重破坏了。我推荐使用Joda Time库。

Joda Time有一个时间间隔的概念:

Interval interval = new Interval(oldTime, new Instant());

编辑:顺便说一下，Joda有两个概念:Interval表示两个时间瞬间之间的时间间隔(表示上午8点到上午10点之间的时间)，Duration表示没有实际时间边界的时间长度(例如表示两个小时!)

如果你只关心时间比较，大多数Date实现(包括JDK)实现了Comparable接口，允许你使用Comparable. compareto ()