java - 当月的开始和结束日期

Question

我需要 Java 中当月的开始日期和结束日期。当 JSP 页面加载当前月份时，它应该自动计算该月的开始日期和结束日期。应该与年份和月份无关。也就是说某个月有 31 天或 30 天或 28 天。这也应该满足闰年的要求。你能帮我解决这个问题吗？

例如，如果我在列表框中选择五月，我需要开始日期为 1，结束日期为 31。

Answer 1

给你:

public Pair<Date, Date> getDateRange() {
    Date begining, end;

    {
        Calendar calendar = getCalendarForNow();
        calendar.set(Calendar.DAY_OF_MONTH,
                calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
        setTimeToBeginningOfDay(calendar);
        begining = calendar.getTime();
    }

    {
        Calendar calendar = getCalendarForNow();
        calendar.set(Calendar.DAY_OF_MONTH,
                calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
        setTimeToEndofDay(calendar);
        end = calendar.getTime();
    }

    return Pair.of(begining, end);
}

private static Calendar getCalendarForNow() {
    Calendar calendar = GregorianCalendar.getInstance();
    calendar.setTime(new Date());
    return calendar;
}

private static void setTimeToBeginningOfDay(Calendar calendar) {
    calendar.set(Calendar.HOUR_OF_DAY, 0);
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    calendar.set(Calendar.MILLISECOND, 0);
}

private static void setTimeToEndofDay(Calendar calendar) {
    calendar.set(Calendar.HOUR_OF_DAY, 23);
    calendar.set(Calendar.MINUTE, 59);
    calendar.set(Calendar.SECOND, 59);
    calendar.set(Calendar.MILLISECOND, 999);
}

PS:Pair类只是一对两个值。