com.jacob.com.DateUtilities Maven / Gradle / Ivy
/*
* Copyright (c) 1999-2004 Sourceforge JACOB Project.
* All rights reserved. Originator: Dan Adler (http://danadler.com).
* Get more information about JACOB at http://sourceforge.net/projects/jacob-project
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package com.jacob.com;
import java.util.Calendar;
import java.util.Date;
/**
* java / windows date conversion utilities
*
* @author joe
*
*/
public class DateUtilities {
/**
* converts a windows time to a Java Date Object
*
* @param comTime
* @return Date object representing the windows time as specified in comTime
*/
static public Date convertWindowsTimeToDate(double comTime) {
return new Date(convertWindowsTimeToMilliseconds(comTime));
}
/**
* Convert a COM time from functions Date(), Time(), Now() to a Java time
* (milliseconds). Visual Basic time values are based to 30.12.1899, Java
* time values are based to 1.1.1970 (= 0 milliseconds). The difference is
* added to the Visual Basic value to get the corresponding Java value. The
* Visual Basic double value reads: .<1
* day percentage fraction>, e.g. "38100.6453" means: 38100 days since
* 30.12.1899 plus (24 hours * 0.6453). Example usage:
* Date javaDate = new Date(toMilliseconds (vbDate));
.
*
* @param comTime
* COM time.
* @return Java time.
*/
static public long convertWindowsTimeToMilliseconds(double comTime) {
long result = 0;
// code from jacobgen:
comTime = comTime - 25569D;
Calendar cal = Calendar.getInstance();
result = Math.round(86400000L * comTime)
- cal.get(Calendar.ZONE_OFFSET);
cal.setTime(new Date(result));
result -= cal.get(Calendar.DST_OFFSET);
return result;
}// convertWindowsTimeToMilliseconds()
/**
* converts a java date to a windows time object (is this timezone safe?)
*
* @param javaDate
* the java date to be converted to windows time
* @return the double representing the date in a form windows understands
*/
static public double convertDateToWindowsTime(Date javaDate) {
if (javaDate == null) {
throw new IllegalArgumentException(
"cannot convert null to windows time");
}
return convertMillisecondsToWindowsTime(javaDate.getTime());
}
/**
* Convert a Java time to a COM time.
*
* @param milliseconds
* Java time.
* @return COM time.
*/
static public double convertMillisecondsToWindowsTime(long milliseconds) {
double result = 0.0;
// code from jacobgen:
Calendar cal = Calendar.getInstance();
cal.setTimeInMillis(milliseconds);
milliseconds += (cal.get(Calendar.ZONE_OFFSET) + cal
.get(Calendar.DST_OFFSET)); // add GMT offset
result = (milliseconds / 86400000D) + 25569D;
return result;
}// convertMillisecondsToWindowsTime()
}