org.w3c.time.TimeZones Maven / Gradle / Ivy
/*
* ====================================================================
* Project: openMDX/Core, http://www.openmdx.org/
* Description: Time Zones
* Owner: OMEX AG, Switzerland, http://www.omex.ch
* ====================================================================
*
* This software is published under the BSD license as listed below.
*
* Copyright (c) 2018, OMEX AG, Switzerland
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* * Neither the name of the openMDX team nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* ------------------
*
* This product includes software developed by other organizations as
* listed in the NOTICE file.
*/
package org.w3c.time;
import java.util.TimeZone;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import javax.xml.datatype.DatatypeConstants;
/**
* Time Zones
*/
public class TimeZones {
private static final TimeZone DEFAULT_TIME_ZONE = TimeZone.getDefault();
/**
* Cache the time zones (but avoid concurrency locks)
*/
private static final ConcurrentMap TIME_ZONES = new ConcurrentHashMap();
/**
*
* Returns a java.util.TimeZone for this class.
*
*
*
* If zoneOffset is FIELD_UNDEFINED, return
* default time zone for this host.
* (Same default as java.util.GregorianCalendar).
*
DatatypeConstants
*
* @param zoneOffset
* the zone offset, or DatatypeConstants.FIELD_UNDEFINED
* in order to retrieve the default time zone
*
* @return TimeZone for this zoneoffset
*/
public static TimeZone toTimeZone(
int zoneOffset
) {
if(zoneOffset == DatatypeConstants.FIELD_UNDEFINED) {
return DEFAULT_TIME_ZONE;
}
final Integer key = Integer.valueOf(zoneOffset);
TimeZone existingTimeZone = TIME_ZONES.get(key);
if (existingTimeZone == null) {
final TimeZone newTimeZone = TimeZone.getTimeZone(toTimeZoneId(zoneOffset));
existingTimeZone = TIME_ZONES.putIfAbsent(key, newTimeZone);
if(existingTimeZone == null) {
return newTimeZone;
}
}
return existingTimeZone;
}
/**
* Calculate a custom time zone id
*
* @param timeZoneOffset
*
* @return the corresponding time zone id
*/
private static String toTimeZoneId(
int timeZoneOffset
) {
final char sign;
final int absoluteOffset;
if (timeZoneOffset < 0) {
sign = '-';
absoluteOffset = -timeZoneOffset;
} else {
sign = '+';
absoluteOffset = timeZoneOffset;
}
String s = Integer.toString(
10000 + 100 * (absoluteOffset / 60) + (absoluteOffset % 60)
);
return "GMT" + sign + s.substring(1, 3) + ':' + s.substring(3);
}
}