判断同一天

http://stackoverflow.com/questions/2517709/comparing-two-dates-to-see-if-they-are-in-the-same-day

Calendar cal1 = Calendar.getInstance();
Calendar cal2 = Calendar.getInstance();
cal1.setTime(date1);
cal2.setTime(date2);
boolean sameDay = cal1.get(Calendar.YEAR) == cal2.get(Calendar.YEAR) &&
                  cal1.get(Calendar.DAY_OF_YEAR) == cal2.get(Calendar.DAY_OF_YEAR);

其实Apache lang包下有DateUtils.isSameDay()。lang包有很多常用的。