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The NetCDF-Java Library is a Java interface to NetCDF files,
as well as to many other types of scientific data formats.
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/*
* Copyright (c) 2010 The University of Reading
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the University of Reading, nor the names of the
* authors or contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 uk.ac.rdg.resc.edal.time;
import java.util.StringTokenizer;
import org.joda.time.Chronology;
import org.joda.time.DateTime;
import org.joda.time.DateTimeZone;
import org.joda.time.chrono.ISOChronology;
/**
* Utility methods for dealing with dates and times.
* todo Does this belong in the cdm package? It's UDUNITS specific.
* @author Jon
*/
public final class TimeUtils
{
/** Private constructor to prevent instantiation */
private TimeUtils() { throw new AssertionError(); }
/**
* Gets the length of the given unit in milliseconds. This accepts
* seconds, minutes, hours and days, and should be constant across calendar
* systems.
*/
public static long getUnitLengthMillis(String unit)
{
unit = unit.trim();
if (unit.equals("seconds") || unit.equals("second") || unit.equals("secs") || unit.equals("sec") || unit.equals("s"))
{
return 1000;
}
else if (unit.equals("minutes") || unit.equals("minute") || unit.equals("mins") || unit.equals("min"))
{
return 1000 * 60;
}
else if (unit.equals("hours") || unit.equals("hour") || unit.equals("hrs") || unit.equals("hr") || unit.equals("h"))
{
return 1000 * 60 * 60;
}
else if (unit.equals("days") || unit.equals("day") || unit.equals("d"))
{
return 1000 * 60 * 60 * 24;
}
else
{
throw new IllegalArgumentException("Unrecognized unit for time axis: " + unit);
}
}
/**
* Parses a UDUNITS time string (of the form "1992-10-8 15:15:42.5 -6:00")
* and returns a DateTime in the ISO Chronology.
* @param baseDateTimeString UDUNITS-formatted time string
* @return a DateTime in the ISO Chronology, with the time zone set to
* UTC.
*/
public static DateTime parseUdunitsTimeString(String baseDateTimeString)
{
return parseUdunitsTimeString(baseDateTimeString, null);
}
/**
* Parses a UDUNITS time string (of the form "1992-10-8 15:15:42.5 -6:00")
* and returns a DateTime in the given Chronology.
* @param baseDateTimeString UDUNITS-formatted time string
* @param chronology The Chronology (calendar system) in which the time string
* is to be interpreted. This must have a time zone of UTC, otherwise an
* IllegalArgumentException will be thrown. If this is null, the ISOChronology
* (in the UTC time zone) will be assumed.
* @return a DateTime in the given Chronology, with the time zone set to
* UTC.
*/
public static DateTime parseUdunitsTimeString(String baseDateTimeString, Chronology chronology)
{
if (chronology == null) chronology = ISOChronology.getInstanceUTC();
if (!chronology.getZone().equals(DateTimeZone.UTC))
{
throw new IllegalArgumentException("The time zone of the Chronology must be UTC");
}
// Set the defaults for any values that are not specified
int year = 0;
int month = 1;
int day = 1;
int hour = 0;
int minute = 0;
double second = 0.0;
// We parse the string using a tokenizer to allow for partial strings
// (e.g. those that contain only the date and not the time)
StringTokenizer tokenizer = new StringTokenizer(baseDateTimeString, " ");
try
{
// Parse the date if present
if (tokenizer.hasMoreTokens())
{
StringTokenizer dateTokenizer = new StringTokenizer(tokenizer.nextToken(), "-");
if (dateTokenizer.hasMoreTokens()) year = Integer.parseInt(dateTokenizer.nextToken());
if (dateTokenizer.hasMoreTokens()) month = Integer.parseInt(dateTokenizer.nextToken());
if (dateTokenizer.hasMoreTokens()) day = Integer.parseInt(dateTokenizer.nextToken());
}
// Parse the time if present
if (tokenizer.hasMoreTokens())
{
StringTokenizer timeTokenizer = new StringTokenizer(tokenizer.nextToken(), ":");
if (timeTokenizer.hasMoreTokens()) hour = Integer.parseInt(timeTokenizer.nextToken());
if (timeTokenizer.hasMoreTokens()) minute = Integer.parseInt(timeTokenizer.nextToken());
if (timeTokenizer.hasMoreTokens()) second = Double.parseDouble(timeTokenizer.nextToken());
}
// Get a DateTime object in this Chronology
DateTime dt = new DateTime(year, month, day, hour, minute, 0, 0, chronology);
// Add the seconds
dt = dt.plus((long)(1000 * second));
// Parse the time zone if present
if (tokenizer.hasMoreTokens())
{
StringTokenizer zoneTokenizer = new StringTokenizer(tokenizer.nextToken(), ":");
int hourOffset = zoneTokenizer.hasMoreTokens() ? Integer.parseInt(zoneTokenizer.nextToken()) : 0;
int minuteOffset = zoneTokenizer.hasMoreTokens() ? Integer.parseInt(zoneTokenizer.nextToken()) : 0;
DateTimeZone dtz = DateTimeZone.forOffsetHoursMinutes(hourOffset, minuteOffset);
// Apply the time zone offset, retaining the field values. This
// manipulates the millisecond instance.
dt = dt.withZoneRetainFields(dtz);
// Now convert to the UTC time zone, retaining the millisecond instant
dt = dt.withZone(DateTimeZone.UTC);
}
return dt;
}
catch (NumberFormatException nfe)
{
throw new IllegalArgumentException("Illegal base time specification "
+ baseDateTimeString);
}
}
}