* @author Michael Harhen
* @author Glen Stampoultzis (glens at apache.org)
* @author Dan Sherman (dsherman at isisph.com)
+ * @author Hack Kampbjorn (hak at 2mba.dk)
*/
public class HSSFDateUtil
}
else
{
+ // Because of daylight time saving we cannot use
+ // date.getTime() - calStart.getTimeInMillis()
+ // as the difference in milliseconds between 00:00 and 04:00
+ // can be 3, 4 or 5 hours but Excel expects it to always
+ // be 4 hours.
+ // E.g. 2004-03-28 04:00 CEST - 2004-03-28 00:00 CET is 3 hours
+ // and 2004-10-31 04:00 CET - 2004-10-31 00:00 CEST is 5 hours
+ double fraction = (((calStart.get(Calendar.HOUR_OF_DAY) * 60
+ + calStart.get(Calendar.MINUTE)
+ ) * 60 + calStart.get(Calendar.SECOND)
+ ) * 1000 + calStart.get(Calendar.MILLISECOND)
+ ) / ( double ) DAY_MILLISECONDS;
calStart = dayStart(calStart);
- double fraction = (date.getTime() - calStart.getTime().getTime())
- / ( double ) DAY_MILLISECONDS;
return fraction + ( double ) absoluteDay(calStart)
- CAL_1900_ABSOLUTE;
* Given an Excel date with either 1900 or 1904 date windowing,
* converts it to a java.util.Date.
*
+ * NOTE: If the default <code>TimeZone</code> in Java uses Daylight
+ * Saving Time then the conversion back to an Excel date may not give
+ * the same value, that is the comparison
+ * <CODE>excelDate == getExcelDate(getJavaDate(excelDate,false))</CODE>
+ * is not always true. For example if default timezone is
+ * <code>Europe/Copenhagen</code>, on 2004-03-28 the minute after
+ * 01:59 CET is 03:00 CEST, if the excel date represents a time between
+ * 02:00 and 03:00 then it is converted to past 03:00 summer time
+ *
* @param date The Excel date.
* @param use1904windowing true if date uses 1904 windowing,
* or false if using 1900 date windowing.
* @return Java representation of the date, or null if date is not a valid Excel date
+ * @see java.util.TimeZone
*/
public static Date getJavaDate(double date, boolean use1904windowing) {
if (isValidExcelDate(date)) {
/* ====================================================================
- Copyright 2002-2004 Apache Software Foundation
+Copyright 2002-2004 Apache Software Foundation
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
- http://www.apache.org/licenses/LICENSE-2.0
+http://www.apache.org/licenses/LICENSE-2.0
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
==================================================================== */
-
+
package org.apache.poi.hssf.usermodel;
import junit.framework.TestCase;
import java.util.Date;
+import java.util.Calendar;
import java.util.GregorianCalendar;
+import java.util.TimeZone;
/**
* Class TestHSSFDateUtil
*
* @author
* @author Dan Sherman (dsherman at isisph.com)
+ * @author Hack Kampbjorn (hak at 2mba.dk)
* @version %I%, %G%
*/
public class TestHSSFDateUtil
- extends TestCase
+ extends TestCase
{
public TestHSSFDateUtil(String s)
{
*/
public void testDateConversion()
- throws Exception
+ throws Exception
{
// Iteratating over the hours exposes any rounding issues.
for (int hour = 0; hour < 23; hour++)
{
GregorianCalendar date = new GregorianCalendar(2002, 0, 1,
- hour, 1, 1);
+ hour, 1, 1);
double excelDate =
- HSSFDateUtil.getExcelDate(date.getTime());
+ HSSFDateUtil.getExcelDate(date.getTime());
assertEquals("Checking hour = " + hour, date.getTime().getTime(),
- HSSFDateUtil.getJavaDate(excelDate).getTime());
+ HSSFDateUtil.getJavaDate(excelDate).getTime());
}
-
+
// check 1900 and 1904 date windowing conversions
double excelDate = 36526.0;
- // with 1900 windowing, excelDate is Jan. 1, 2000
- // with 1904 windowing, excelDate is Jan. 2, 2004
+ // with 1900 windowing, excelDate is Jan. 1, 2000
+ // with 1904 windowing, excelDate is Jan. 2, 2004
GregorianCalendar cal = new GregorianCalendar(2000,0,1); // Jan. 1, 2000
Date dateIf1900 = cal.getTime();
cal.add(GregorianCalendar.YEAR,4); // now Jan. 1, 2004
Date dateIf1904 = cal.getTime();
// 1900 windowing
assertEquals("Checking 1900 Date Windowing",
- dateIf1900.getTime(),
- HSSFDateUtil.getJavaDate(excelDate,false).getTime());
+ dateIf1900.getTime(),
+ HSSFDateUtil.getJavaDate(excelDate,false).getTime());
// 1904 windowing
assertEquals("Checking 1904 Date Windowing",
- dateIf1904.getTime(),
- HSSFDateUtil.getJavaDate(excelDate,true).getTime());
+ dateIf1904.getTime(),
+ HSSFDateUtil.getJavaDate(excelDate,true).getTime());
}
+
+ /**
+ * Checks the conversion of a java.util.date to Excel on a day when
+ * Daylight Saving Time starts.
+ */
+ public void testExcelConversionOnDSTStart() {
+ TimeZone cet = TimeZone.getTimeZone("Europe/Copenhagen");
+ TimeZone.setDefault(cet);
+ Calendar cal = new GregorianCalendar(2004, Calendar.MARCH, 28);
+ for (int hour = 0; hour < 24; hour++) {
+
+ // Skip 02:00 CET as that is the Daylight change time
+ // and Java converts it automatically to 03:00 CEST
+ if (hour == 2) {
+ continue;
+ }
+
+ cal.set(Calendar.HOUR_OF_DAY, hour);
+ Date javaDate = cal.getTime();
+ double excelDate = HSSFDateUtil.getExcelDate(javaDate);
+ double difference = excelDate - Math.floor(excelDate);
+ int differenceInHours = (int) (difference * 24 * 60 + 0.5) / 60;
+ assertEquals("Checking " + hour + " hour on Daylight Saving Time start date",
+ hour,
+ differenceInHours);
+ assertEquals("Checking " + hour + " hour on Daylight Saving Time start date",
+ javaDate.getTime(),
+ HSSFDateUtil.getJavaDate(excelDate).getTime());
+ }
+ }
+
+ /**
+ * Checks the conversion of an Excel date to a java.util.date on a day when
+ * Daylight Saving Time starts.
+ */
+ public void testJavaConversionOnDSTStart() {
+ TimeZone cet = TimeZone.getTimeZone("Europe/Copenhagen");
+ TimeZone.setDefault(cet);
+ Calendar cal = new GregorianCalendar(2004, Calendar.MARCH, 28);
+ double excelDate = HSSFDateUtil.getExcelDate(cal.getTime());
+ double oneHour = 1.0 / 24;
+ double oneMinute = oneHour / 60;
+ for (int hour = 0; hour < 24; hour++, excelDate += oneHour) {
+
+ // Skip 02:00 CET as that is the Daylight change time
+ // and Java converts it automatically to 03:00 CEST
+ if (hour == 2) {
+ continue;
+ }
+
+ cal.set(Calendar.HOUR_OF_DAY, hour);
+ Date javaDate = HSSFDateUtil.getJavaDate(excelDate);
+ assertEquals("Checking " + hour + " hours on Daylight Saving Time start date",
+ excelDate,
+ HSSFDateUtil.getExcelDate(javaDate), oneMinute);
+ }
+ }
+
+ /**
+ * Checks the conversion of a java.util.Date to Excel on a day when
+ * Daylight Saving Time ends.
+ */
+ public void testExcelConversionOnDSTEnd() {
+ TimeZone cet = TimeZone.getTimeZone("Europe/Copenhagen");
+ TimeZone.setDefault(cet);
+ Calendar cal = new GregorianCalendar(2004, Calendar.OCTOBER, 31);
+ for (int hour = 0; hour < 24; hour++) {
+ cal.set(Calendar.HOUR_OF_DAY, hour);
+ Date javaDate = cal.getTime();
+ double excelDate = HSSFDateUtil.getExcelDate(javaDate);
+ double difference = excelDate - Math.floor(excelDate);
+ int differenceInHours = (int) (difference * 24 * 60 + 0.5) / 60;
+ assertEquals("Checking " + hour + " hour on Daylight Saving Time end date",
+ hour,
+ differenceInHours);
+ assertEquals("Checking " + hour + " hour on Daylight Saving Time start date",
+ javaDate.getTime(),
+ HSSFDateUtil.getJavaDate(excelDate).getTime());
+ }
+ }
+
+ /**
+ * Checks the conversion of an Excel date to java.util.Date on a day when
+ * Daylight Saving Time ends.
+ */
+ public void testJavaConversionOnDSTEnd() {
+ TimeZone cet = TimeZone.getTimeZone("Europe/Copenhagen");
+ TimeZone.setDefault(cet);
+ Calendar cal = new GregorianCalendar(2004, Calendar.OCTOBER, 31);
+ double excelDate = HSSFDateUtil.getExcelDate(cal.getTime());
+ double oneHour = 1.0 / 24;
+ double oneMinute = oneHour / 60;
+ for (int hour = 0; hour < 24; hour++, excelDate += oneHour) {
+ cal.set(Calendar.HOUR_OF_DAY, hour);
+ Date javaDate = HSSFDateUtil.getJavaDate(excelDate);
+ assertEquals("Checking " + hour + " hours on Daylight Saving Time start date",
+ excelDate,
+ HSSFDateUtil.getExcelDate(javaDate), oneMinute);
+ }
+ }
+
+ public static void main(String [] args) {
+ System.out
+ .println("Testing org.apache.poi.hssf.usermodel.TestHSSFDateUtil");
+ junit.textui.TestRunner.run(TestHSSFDateUtil.class);
+ }
+
}
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