/**
  * 计算分割段数
  *
  * @param period 时段周期 [时|日|周|月]
  * @param start 开始时间
  * @param end 结束时间
  * @return 段数
  */
 private int countDays(Period period, Date start, Date end) {
   Calendar calendar = Calendar.getInstance();
   calendar.setTime(start);
   int count = 0;
   while (calendar.getTime().before(end)) {
     count++;
     calendar.add(period.getField(), 1);
   }
   return count;
 }
 /**
  * 检测时间分段合理性
  *
  * @param period 时段周期 [时|日|周|月]
  * @param start 开始时间
  * @param end 结束时间
  */
 private void doCheckPeriod(Period period, Date start, Date end) throws ServiceException {
   Calendar calendar = Calendar.getInstance();
   calendar.setTime(start);
   int count = 0, max = 200;
   while (calendar.getTime().before(end)) {
     if (count++ > max) {
       throw new ServiceException("数据量偏大,请调整时间跨度再试!");
     }
     calendar.add(period.getField(), 1);
   }
 }
 /**
  * 填充数据
  *
  * @param list 数据库有效数据列表
  * @return 填充的数据
  */
 private <T extends TrendValue> List<T> fulldata(
     List<T> list, DateFormat format, int field, Date start, Date end, Class<T> clazz) {
   Map<String, T> map = tomap(list);
   Calendar calendar = Calendar.getInstance();
   calendar.setTime(start);
   List<T> nlist = new ArrayList<>();
   while (calendar.getTime().before(end)) {
     String keytime = format.format(calendar.getTime());
     T value = map.get(keytime);
     if (value == null) {
       value = AfReflecter.newInstance(clazz);
       value.setEmpty();
       value.setDate(keytime);
       value.setTime(calendar.getTime());
       nlist.add(value);
     } else {
       nlist.add(value);
       map.remove(keytime);
     }
     calendar.add(field, 1);
   }
   for (Map.Entry<String, T> entry : map.entrySet()) {
     nlist.add(entry.getValue());
   }
   return nlist;
 }
 /**
  * 根据周期和便宜计算结束时间
  *
  * @param end 结束时间
  * @param span 时间跨度
  * @param offset 偏移
  * @return 结束时间
  */
 private Date timeEnd(Date end, Period span, Integer offset) {
   if (span != null && offset != null /* && !Period.hour.equals(span)*/) {
     DateFormat format = span.getFormat();
     Calendar calendar = Calendar.getInstance();
     try {
       calendar.setTime(format.parse(format.format(calendar.getTime())));
     } catch (ParseException e) {
       e.printStackTrace();
     }
     calendar.add(span.getField(), offset + 1);
     return calendar.getTime();
   }
   if (end == null) {
     return timeEnd(new Date(), Period.year, 1000);
   }
   return end;
 }
 /**
  * 根据周期和便宜计算开始时间
  *
  * @param start 开始时间
  * @param span 时间跨度
  * @param offset 偏移
  * @return 开始时间
  */
 private Date timeStart(Date start, Period span, Integer offset) {
   if (span != null && offset != null) {
     DateFormat format = span.getFormat();
     Calendar calendar = Calendar.getInstance();
     try {
       calendar.setTime(format.parse(format.format(calendar.getTime())));
     } catch (ParseException e) {
       e.printStackTrace();
     }
     calendar.add(span.getField(), offset);
     return calendar.getTime();
   }
   if (start == null) {
     return timeStart(new Date(), Period.year, -1000);
   }
   return start;
 }