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A Java library for reading and writing iCalendar (*.ics) files
/**
* Copyright (c) 2012, Ben Fortuna
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* o Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* o 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.
*
* o Neither the name of Ben Fortuna nor the names of any other 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.
*/
package net.fortuna.ical4j.util;
import java.util.TimeZone;
/**
* $Id$ [5/07/2004]
*
* Utility methods relevant to Java timezones.
*
* @author Ben Fortuna
*/
public final class TimeZones {
/**
* The timezone identifier for UTC time.
*/
public static final String UTC_ID = "Etc/UTC";
/**
* The timezone identifier for UTC time in the IBM JVM.
*/
public static final String IBM_UTC_ID = "GMT";
/**
* The timezone identifier for GMT time.
*/
public static final String GMT_ID = "Etc/GMT";
private static final TimeZone UTC_TIMEZONE;
static {
UTC_TIMEZONE = TimeZone.getTimeZone(UTC_ID);
}
/**
* Constructor made private to enforce static nature.
*/
private TimeZones() {
}
/**
* Indicates whether the specified timezone is equivalent to
* UTC time.
* @param timezone a timezone instance
* @return true if the timezone is UTC time, otherwise false
*/
public static boolean isUtc(final TimeZone timezone) {
// return timezone.hasSameRules(TimeZone.getTimeZone(UTC_ID));
// return timezone.getRawOffset() == 0;
return UTC_ID.equals(timezone.getID())
|| IBM_UTC_ID.equals(timezone.getID());
}
public static TimeZone getDefault() {
if ("true".equals(Configurator.getProperty("net.fortuna.ical4j.timezone.default.utc").orElse("false"))) {
return getUtcTimeZone();
}
return TimeZone.getDefault();
}
/**
* Although timezones are not really applicable to DATE instances in iCalendar, the implementation
* in iCal4j requires the use of a timezone. Dates in iCal4j may be either "floating", in that they
* use the default Java timezone, or alternatively will use UTC (this is the default).
*
* The use of floating dates may be configured by specifying the following as a system property or in
* a file called "ical4j.properties" in the classpath:
*
* net.fortuna.ical4j.timezone.date.floating=true
*
* @return the timezone used for date instances
*/
public static TimeZone getDateTimeZone() {
if ("true".equals(Configurator.getProperty("net.fortuna.ical4j.timezone.date.floating").orElse("false"))) {
return TimeZone.getDefault();
}
return getUtcTimeZone();
}
/**
* Get the UTC Timezone.
*/
public static TimeZone getUtcTimeZone() {
return UTC_TIMEZONE;
}
}