根据传的日期获取当天的0点和23点

//00:00:00
public static Date getDay(Date when) {
      Date date = truncate(when, Calendar.DATE);
//    date = addDays(date, -1);
      date.setTime(date.getTime());
      return date;
   }

//23:59:59

public static Date getDayEnd(Date when) {
   Date date = truncate(when, Calendar.DATE);
   date = addDays(date, 1);
   date.setTime(date.getTime() - 1);
   return date;
}