345 lines
12 KiB
Java
345 lines
12 KiB
Java
/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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/*
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* DateUtil.java
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*
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* Created on January 19, 2002, 9:30 AM
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*/
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package org.apache.poi.hssf.usermodel;
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import java.util.Calendar;
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import java.util.Date;
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import java.util.GregorianCalendar;
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/**
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* Contains methods for dealing with Excel dates.
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*
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* @author Michael Harhen
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* @author Glen Stampoultzis (glens at apache.org)
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* @author Dan Sherman (dsherman at isisph.com)
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* @author Hack Kampbjorn (hak at 2mba.dk)
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*/
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public class HSSFDateUtil
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{
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private HSSFDateUtil()
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{
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}
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private static final int BAD_DATE =
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-1; // used to specify that date is invalid
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private static final long DAY_MILLISECONDS = 24 * 60 * 60 * 1000;
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/**
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* Given a Date, converts it into a double representing its internal Excel representation,
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* which is the number of days since 1/1/1900. Fractional days represent hours, minutes, and seconds.
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*
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* @return Excel representation of Date (-1 if error - test for error by checking for less than 0.1)
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* @param date the Date
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*/
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public static double getExcelDate(Date date)
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{
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Calendar calStart = new GregorianCalendar();
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calStart.setTime(
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date); // If date includes hours, minutes, and seconds, set them to 0
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if (calStart.get(Calendar.YEAR) < 1900)
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{
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return BAD_DATE;
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}
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else
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{
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// Because of daylight time saving we cannot use
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// date.getTime() - calStart.getTimeInMillis()
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// as the difference in milliseconds between 00:00 and 04:00
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// can be 3, 4 or 5 hours but Excel expects it to always
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// be 4 hours.
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// E.g. 2004-03-28 04:00 CEST - 2004-03-28 00:00 CET is 3 hours
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// and 2004-10-31 04:00 CET - 2004-10-31 00:00 CEST is 5 hours
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double fraction = (((calStart.get(Calendar.HOUR_OF_DAY) * 60
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+ calStart.get(Calendar.MINUTE)
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) * 60 + calStart.get(Calendar.SECOND)
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) * 1000 + calStart.get(Calendar.MILLISECOND)
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) / ( double ) DAY_MILLISECONDS;
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calStart = dayStart(calStart);
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double value = fraction + absoluteDay(calStart);
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if (value >= 60) {
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value += 1;
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}
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return value;
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}
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}
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/**
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* Given a excel date, converts it into a Date.
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* Assumes 1900 date windowing.
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*
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* @param date the Excel Date
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*
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* @return Java representation of a date (null if error)
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* @see #getJavaDate(double,boolean)
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*/
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public static Date getJavaDate(double date)
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{
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return getJavaDate(date,false);
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}
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/**
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* Given an Excel date with either 1900 or 1904 date windowing,
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* converts it to a java.util.Date.
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*
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* NOTE: If the default <code>TimeZone</code> in Java uses Daylight
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* Saving Time then the conversion back to an Excel date may not give
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* the same value, that is the comparison
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* <CODE>excelDate == getExcelDate(getJavaDate(excelDate,false))</CODE>
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* is not always true. For example if default timezone is
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* <code>Europe/Copenhagen</code>, on 2004-03-28 the minute after
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* 01:59 CET is 03:00 CEST, if the excel date represents a time between
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* 02:00 and 03:00 then it is converted to past 03:00 summer time
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*
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* @param date The Excel date.
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* @param use1904windowing true if date uses 1904 windowing,
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* or false if using 1900 date windowing.
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* @return Java representation of the date, or null if date is not a valid Excel date
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* @see java.util.TimeZone
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*/
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public static Date getJavaDate(double date, boolean use1904windowing) {
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if (isValidExcelDate(date)) {
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int startYear = 1900;
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int dayAdjust = -1; // Excel thinks 2/29/1900 is a valid date, which it isn't
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int wholeDays = (int)Math.floor(date);
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if (use1904windowing) {
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startYear = 1904;
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dayAdjust = 1; // 1904 date windowing uses 1/2/1904 as the first day
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}
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else if (wholeDays < 61) {
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// Date is prior to 3/1/1900, so adjust because Excel thinks 2/29/1900 exists
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// If Excel date == 2/29/1900, will become 3/1/1900 in Java representation
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dayAdjust = 0;
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}
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GregorianCalendar calendar = new GregorianCalendar(startYear,0,
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wholeDays + dayAdjust);
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int millisecondsInDay = (int)((date - Math.floor(date)) *
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(double) DAY_MILLISECONDS + 0.5);
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calendar.set(GregorianCalendar.MILLISECOND, millisecondsInDay);
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return calendar.getTime();
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}
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else {
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return null;
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}
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}
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/**
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* Given a format ID and its format String, will check to see if the
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* format represents a date format or not.
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* Firstly, it will check to see if the format ID corresponds to an
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* internal excel date format (eg most US date formats)
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* If not, it will check to see if the format string only contains
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* date formatting characters (ymd-/), which covers most
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* non US date formats.
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*
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* @param formatIndex The index of the format, eg from ExtendedFormatRecord.getFormatIndex
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* @param formatString The format string, eg from FormatRecord.getFormatString
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* @see #isInternalDateFormat(int)
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*/
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public static boolean isADateFormat(int formatIndex, String formatString) {
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// First up, is this an internal date format?
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if(isInternalDateFormat(formatIndex)) {
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return true;
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}
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// If we didn't get a real string, it can't be
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if(formatString == null || formatString.length() == 0) {
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return false;
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}
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String fs = formatString;
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// Translate \- into just -, before matching
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fs = fs.replaceAll("\\\\-","-");
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// And \, into ,
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fs = fs.replaceAll("\\\\,",",");
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// And '\ ' into ' '
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fs = fs.replaceAll("\\\\ "," ");
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// If it end in ;@, that's some crazy dd/mm vs mm/dd
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// switching stuff, which we can ignore
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fs = fs.replaceAll(";@", "");
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// If it starts with [$-...], then it is a date, but
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// who knows what that starting bit is all about
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fs = fs.replaceAll("\\[\\$\\-.*?\\]", "");
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// Otherwise, check it's only made up of:
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// y m d - / ,
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if(fs.matches("^[ymd\\-/, ]+$")) {
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return true;
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}
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return false;
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}
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/**
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* Given a format ID this will check whether the format represents
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* an internal excel date format or not.
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* @see #isADateFormat(int, java.lang.String)
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*/
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public static boolean isInternalDateFormat(int format) {
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boolean retval =false;
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switch(format) {
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// Internal Date Formats as described on page 427 in
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// Microsoft Excel Dev's Kit...
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case 0x0e:
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case 0x0f:
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case 0x10:
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case 0x11:
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case 0x12:
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case 0x13:
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case 0x14:
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case 0x15:
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case 0x16:
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case 0x2d:
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case 0x2e:
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case 0x2f:
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retval = true;
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break;
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default:
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retval = false;
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break;
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}
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return retval;
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}
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/**
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* Check if a cell contains a date
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* Since dates are stored internally in Excel as double values
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* we infer it is a date if it is formatted as such.
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* @see #isADateFormat(int,string)
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* @see #isInternalDateFormat(int)
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*/
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public static boolean isCellDateFormatted(HSSFCell cell) {
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if (cell == null) return false;
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boolean bDate = false;
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double d = cell.getNumericCellValue();
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if ( HSSFDateUtil.isValidExcelDate(d) ) {
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HSSFCellStyle style = cell.getCellStyle();
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int i = style.getDataFormat();
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String f = style.getDataFormatString(cell.getBoundWorkbook());
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bDate = isADateFormat(i, f);
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}
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return bDate;
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}
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/**
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* Check if a cell contains a date, checking only for internal
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* excel date formats.
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* As Excel stores a great many of its dates in "non-internal"
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* date formats, you will not normally want to use this method.
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* @see #isADateFormat(int,string)
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* @see #isInternalDateFormat(int)
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*/
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public static boolean isCellInternalDateFormatted(HSSFCell cell) {
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if (cell == null) return false;
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boolean bDate = false;
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double d = cell.getNumericCellValue();
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if ( HSSFDateUtil.isValidExcelDate(d) ) {
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HSSFCellStyle style = cell.getCellStyle();
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int i = style.getDataFormat();
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bDate = isInternalDateFormat(i);
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}
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return bDate;
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}
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/**
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* Given a double, checks if it is a valid Excel date.
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*
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* @return true if valid
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* @param value the double value
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*/
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public static boolean isValidExcelDate(double value)
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{
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return (value > -Double.MIN_VALUE);
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}
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/**
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* Given a Calendar, return the number of days since 1900/12/31.
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*
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* @return days number of days since 1900/12/31
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* @param cal the Calendar
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* @exception IllegalArgumentException if date is invalid
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*/
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private static int absoluteDay(Calendar cal)
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{
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return cal.get(Calendar.DAY_OF_YEAR)
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+ daysInPriorYears(cal.get(Calendar.YEAR));
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}
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/**
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* Return the number of days in prior years since 1900
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*
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* @return days number of days in years prior to yr.
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* @param yr a year (1900 < yr < 4000)
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* @exception IllegalArgumentException if year is outside of range.
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*/
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private static int daysInPriorYears(int yr)
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{
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if (yr < 1900) {
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throw new IllegalArgumentException(
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"'year' must be 1900 or greater");
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}
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int yr1 = yr - 1;
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int leapDays = yr1 / 4 // plus julian leap days in prior years
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- yr1 / 100 // minus prior century years
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+ yr1 / 400 // plus years divisible by 400
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- 460; // leap days in previous 1900 years
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return 365 * (yr - 1900) + leapDays;
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}
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// set HH:MM:SS fields of cal to 00:00:00:000
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private static Calendar dayStart(final Calendar cal)
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{
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cal.get(Calendar
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.HOUR_OF_DAY); // force recalculation of internal fields
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cal.set(Calendar.HOUR_OF_DAY, 0);
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cal.set(Calendar.MINUTE, 0);
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cal.set(Calendar.SECOND, 0);
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cal.set(Calendar.MILLISECOND, 0);
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cal.get(Calendar
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.HOUR_OF_DAY); // force recalculation of internal fields
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return cal;
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}
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// ---------------------------------------------------------------------------------------------------------
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}
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