*/
  public static Timestamp ZERO_TIMESTAMP = new Timestamp( (long) 00000000000000);
  public static String NULL_TIMESTAMP_DISPLAY = "1970-01-01 00:00:00";

  /**
   * Value needed to create Timestamp representing
   * "January 1, 1970 00:00:00".
   * From the documentation, you would think this would be
   * Timestamp(0), but empirical tests show it to be
   * Timestamp(18000000).
   */
  public static long NULL_TIME = (long) 18000000;

  /**
   * Timestamp representing "January 1, 1970 00:00:00".
   */
  public static Timestamp NULL_TIMESTAMP = new Timestamp(NULL_TIME);

  /**
   * Timestamp representing "December 31, 2029, 23:59:59.9"
   */
  public static Timestamp MAX_TIMESTAMP = Timestamp.valueOf(
      "2029-12-31 23:59:59.999");

  /**
   * Return the String representing "January 1, 1970 00:00:00".
   */
  public static String getTimestampDisplayNull() {
    return NULL_TIMESTAMP_DISPLAY;
  }

  /**
   * Return the String representing the current timestamp;
   */
  public static String getTimestampDisplay() {
    return getTimestamp(new Timestamp(System.currentTimeMillis()));
  }

  /**
   * @deprecated Use getTimestampDisplay.
   */
  public static String getTimestampText() {
    return getTimestampDisplay();
  }

  /**
   * Return null if timestamp is null or equals
   * "January 1, 1970 00:00:00".
   */
  public static boolean isNull(Timestamp timestamp) {
    return ( (timestamp == null) || (timestamp.getTime() == NULL_TIME));
  }

  /**
   * Factory method to return timestamp initialized to
   * current system time.
   * For timestamp as a String in the default format,
   * use <code>getTimestamp().toString()</code>.
   */
  public static Timestamp getTimestamp() {
    return new Timestamp(System.currentTimeMillis());
  }

  /**
   * Convert timestamp to String for given locale in given style.
   * A null locale will return the default locale.
   */
  public static String getTimestamp(Timestamp timestamp,
                                    Locale locale, int style) {
    Date date = (Date) timestamp;
    if (locale == null) {
      return (DateFormat.getDateTimeInstance(style, style).
              format(date));
    }
    return (DateFormat.getDateTimeInstance(style, style, locale).
            format(date));
  }

  /**
   * Convert date to String for default locale in given style.
   * A null locale will return the default locale.
   */
  public static String getTimestamp(Timestamp timestamp,
                                    int style) {
    return getTimestamp(timestamp, (Locale)null, style);
  }

  /**
   * Convert date to String for default locale in DEFAULT style.
   * A null locale will return the default locale.
   */
  public static String getTimestamp(Timestamp timestamp) {
    return getTimestamp(timestamp, (Locale)null, DEFAULT);
  }

  /**
   * Return Timestamp value using a String.
   * Null or conversion error returns null.
   * @param String representing Timestamp
   */
  public static Timestamp toTimestamp(String string) {
    if (string == null) {
      return null;
    }
    else {
      try {
        return Timestamp.valueOf(string);
      }
      catch (Throwable t) {
        return null;
      }
    }
  }

  /**
   * Return a Timestamp based on the parameters.
   * Any nulls or conversion error returns null.
   * @param year The year
   * @param month The month
   * @param day The day
   * @returns Timestamp for year-month-day
   */
  public static Timestamp toTimestamp(String year, String month, String day) {

    if ( (null == year) || (null == month) || (null == day)) {
      return null;
    }

    StringBuffer sb = new StringBuffer();
    // YEAR-MM-DD 00:00:00.0
    sb.append(year);
    sb.append(DATE_SEPARATOR);
    sb.append(month);
    sb.append(DATE_SEPARATOR);
    sb.append(day);

    sb.append(TIMESTAMP_TIME_ZERO);

    return toTimestamp(sb.toString());
  }

  /**
   * Return String value representing Timestamp.
   * Null returns null.
   * @param Timestamp
   */
  public static String toString(Timestamp timestamp) {
    if (timestamp == null) {
      return null;
    }
    else {
      return timestamp.toString();
    }
  }

  // 當前日期加減n天后的日期，返回String (yyyy-mm-dd)
  public static String nDaysAftertoday(int n) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Calendar rightNow = Calendar.getInstance();
    //rightNow.add(Calendar.DAY_OF_MONTH,-1);
    rightNow.add(Calendar.DAY_OF_MONTH, +n);
    return df.format(rightNow.getTime());
  }

  // 當前日期加減n天后的日期，返回Date
  public static Date nDaysAfterNowDate(int n) {
    Calendar rightNow = Calendar.getInstance();
    //rightNow.add(Calendar.DAY_OF_MONTH,-1);
    rightNow.add(Calendar.DAY_OF_MONTH, +n);
    return rightNow.getTime();
  }

  // 給定一個日期型字符串，返回加減n天后的日期型字符串
  public static String nDaysAfterOneDateString(String basicDate, int n) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Date tmpDate = null;
    try {
      tmpDate = df.parse(basicDate);
    }
    catch (Exception e) {
      // 日期型字符串格式錯誤
    }
    long nDay = (tmpDate.getTime() / (24 * 60 * 60 * 1000) + 1 + n) *
        (24 * 60 * 60 * 1000);
    tmpDate.setTime(nDay);

    return df.format(tmpDate);
  }

  // 給定一個日期，返回加減n天后的日期，返回Date
  public static Date nDaysAfterOneDate(Date basicDate, int n) {
    long nDay = (basicDate.getTime() / (24 * 60 * 60 * 1000) + 1 + n) *
        (24 * 60 * 60 * 1000);
    basicDate.setTime(nDay);

    return basicDate;
  }

  // 當前日期加減n個月后的日期，返回String (yyyy-mm-dd)
  public static String nMonthsAftertoday(int n) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Calendar rightNow = Calendar.getInstance();
    //rightNow.add(Calendar.DAY_OF_MONTH,-1);
    rightNow.add(Calendar.MONTH, +n);
    return df.format(rightNow.getTime());
  }

  // 當前日期加減n個月后的日期，返回Date
  public static Date nMonthsAfterNowDate(int n) {
    Calendar rightNow = Calendar.getInstance();
    //rightNow.add(Calendar.DAY_OF_MONTH,-1);
    rightNow.add(Calendar.MONTH, +n);
    return rightNow.getTime();
  }

  // 當前日期加減n個月后的日期，返回Date
  public static Date nMonthsAfterOneDate(Date basicDate, int n) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Calendar rightNow = Calendar.getInstance();
    rightNow.setTime(basicDate);
    rightNow.add(Calendar.MONTH, +n);
    return rightNow.getTime();
  }

  // 當前日期加減n個月后的日期，返回String
  public static String nMonthsAfterOneDateString(Date basicDate, int n) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Calendar rightNow = Calendar.getInstance();
    rightNow.setTime(basicDate);
    rightNow.add(Calendar.MONTH, +n);
    return df.format(rightNow.getTime());
  }

  //	計算兩個日期相隔的天數
  public static int nDaysBetweenTwoDate(Date firstDate, Date secondDate) {
    int nDay = (int) ( (secondDate.getTime() - firstDate.getTime()) /
                      (24 * 60 * 60 * 1000));
    return nDay;
  }

  // 計算兩個日期相隔的天數
  public static int nDaysBetweenTwoDate(String firstString, String secondString) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    Date firstDate = null;
    Date secondDate = null;
    try {
      firstDate = df.parse(firstString);
      secondDate = df.parse(secondString);
    }
    catch (Exception e) {
      // 日期型字符串格式錯誤
    }

    int nDay = (int) ( (secondDate.getTime() - firstDate.getTime()) /
                      (24 * 60 * 60 * 1000));
    return nDay;
  }

  //得到給定日期是星期幾（從星期天開始,1-7）
  public static int getWeekNumOfDate(Date date) {
    GregorianCalendar calendar = (GregorianCalendar) GregorianCalendar.
        getInstance();
    calendar.setTime(date);
    return calendar.get(GregorianCalendar.DAY_OF_WEEK);
  }

  public static int getWeekNumOfDate(String date) {
    GregorianCalendar calendar = (GregorianCalendar) GregorianCalendar.
        getInstance();
    calendar.setTime(DateTimeUtils.toDate(date));
    return calendar.get(GregorianCalendar.DAY_OF_WEEK);
  }

  //得到給定日期所在星期的某一天的日期
  //weekDay: from sunday to SATURDAY，1 to 7
  public static Date getWeekDayDate(int weekDay, Date date) {
    Calendar c = Calendar.getInstance();
    c.setTime(date);
    if (weekDay >= Calendar.SUNDAY && weekDay <= Calendar.SATURDAY) {
      int delta = weekDay - c.get(Calendar.DAY_OF_WEEK);
      c.add(Calendar.DAY_OF_WEEK, delta);
    }
    return new Date(c.getTimeInMillis());
  }

  public static GregorianCalendar getnDayDiff(GregorianCalendar cal, int n) {
    GregorianCalendar g1 = new GregorianCalendar(cal.get(Calendar.YEAR),
                                                 cal.get(Calendar.MONTH),
                                                 cal.get(Calendar.DAY_OF_MONTH));
    g1.add(Calendar.DAY_OF_MONTH, +n);
    return g1;
  }

  public static GregorianCalendar getnMonthDiff(GregorianCalendar cal, int n) {
    GregorianCalendar g1 = new GregorianCalendar(cal.get(Calendar.YEAR),
                                                 cal.get(Calendar.MONTH),
                                                 cal.get(Calendar.DAY_OF_MONTH));
    g1.add(Calendar.MONTH, +n);
    return g1;
  }

  public static GregorianCalendar getnYearDiff(GregorianCalendar cal, int n) {
    GregorianCalendar g1 = new GregorianCalendar(cal.get(Calendar.YEAR),
                                                 cal.get(Calendar.MONTH),
                                                 cal.get(Calendar.DAY_OF_MONTH));
    g1.add(Calendar.YEAR, +n);
    return g1;
  }

  public static String long2DateString(String longVal) {
    if (Long.parseLong(longVal) <= 0) {
      return "";
    }
    return dateToShortString(long2Date(longVal));
  }

  public static String long2DateString(String longVal, String format) {
    if (Long.parseLong(longVal) <= 0) {
      return "";
    }
    return dateToShortString(long2Date(longVal), format);
  }

  /**
   * 取得間隔的天數
   * @param begin long
   * @param end long
   * @return int
   */
  public static int getDayDiff(long begin, long end) {
    long interval = end - begin;
    if (interval > 0) {
      return (int) (interval / 3600 / 1000 / 24);
    }
    return 0;
  }

  public static int getDayDiff(String beginStr, String endStr) {
    try {
      long begin = Long.parseLong(beginStr);
      long end = Long.parseLong(endStr);
      return getDayDiff(begin, end);
    }
    catch (Exception e) {

    }
    return 0;
  }

}