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Java library for reading and writing FITS files. FITS, the Flexible Image Transport System, is the format commonly used in the archiving and transport of astronomical data.
package nom.tam.fits;
/*
* #%L
* nom.tam FITS library
* %%
* Copyright (C) 1996 - 2024 nom-tam-fits
* %%
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
* #L%
*/
import java.text.DecimalFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* ISO timestamp support for FITS headers. Such timestamps are used with DATE style header keywords, such
* as DATE-OBS or DATE-END.
*/
public class FitsDate implements Comparable {
/**
* logger to log to.
*/
private static final int FIRST_THREE_CHARACTER_VALUE = 100;
private static final int FIRST_TWO_CHARACTER_VALUE = 10;
private static final int FITS_DATE_STRING_SIZE = 23;
private static final TimeZone UTC = TimeZone.getTimeZone("UTC");
private static final int NEW_FORMAT_DAY_OF_MONTH_GROUP = 4;
private static final int NEW_FORMAT_HOUR_GROUP = 6;
private static final int NEW_FORMAT_MILLISECOND_GROUP = 10;
private static final int NEW_FORMAT_MINUTE_GROUP = 7;
private static final int NEW_FORMAT_MONTH_GROUP = 3;
private static final int NEW_FORMAT_SECOND_GROUP = 8;
private static final int NEW_FORMAT_YEAR_GROUP = 2;
private static final Pattern NORMAL_REGEX = Pattern.compile(
"\\s*(([0-9][0-9][0-9][0-9])-([0-9][0-9])-([0-9][0-9]))(T([0-9][0-9]):([0-9][0-9]):([0-9][0-9])(\\.([0-9]+))?)?\\s*");
private static final int OLD_FORMAT_DAY_OF_MONTH_GROUP = 1;
private static final int OLD_FORMAT_MONTH_GROUP = 2;
private static final int OLD_FORMAT_YEAR_GROUP = 3;
private static final Pattern OLD_REGEX = Pattern.compile("\\s*([0-9][0-9])/([0-9][0-9])/([0-9][0-9])\\s*");
private static final int YEAR_OFFSET = 1900;
private static final int NB_DIGITS_MILLIS = 3;
private static final int POW_TEN = 10;
/**
* Returns the FITS date string for the current date and time.
*
* @return the current date in FITS date format
*
* @see #getFitsDateString(Date)
*/
public static String getFitsDateString() {
return getFitsDateString(new Date(), true);
}
/**
* Returns the FITS date string for a specific date and time
*
* @return a created FITS format date string Java Date object.
*
* @param epoch The epoch to be converted to FITS format.
*
* @see #getFitsDateString(Date, boolean)
* @see #getFitsDateString()
*/
public static String getFitsDateString(Date epoch) {
return getFitsDateString(epoch, true);
}
/**
* Returns the FITS date string, with or without the time component, for a specific date and time.
*
* @return a created FITS format date string. Note that the date is not rounded.
*
* @param epoch The epoch to be converted to FITS format.
* @param timeOfDay Whether the time of day information shouldd be included
*
* @see #getFitsDateString(Date)
* @see #getFitsDateString()
*/
public static String getFitsDateString(Date epoch, boolean timeOfDay) {
Calendar cal = Calendar.getInstance(UTC);
cal.setTime(epoch);
StringBuilder fitsDate = new StringBuilder();
DecimalFormat df = new DecimalFormat("0000");
fitsDate.append(df.format(cal.get(Calendar.YEAR)));
fitsDate.append("-");
df = new DecimalFormat("00");
fitsDate.append(df.format(cal.get(Calendar.MONTH) + 1));
fitsDate.append("-");
fitsDate.append(df.format(cal.get(Calendar.DAY_OF_MONTH)));
if (timeOfDay) {
fitsDate.append("T");
fitsDate.append(df.format(cal.get(Calendar.HOUR_OF_DAY)));
fitsDate.append(":");
fitsDate.append(df.format(cal.get(Calendar.MINUTE)));
fitsDate.append(":");
fitsDate.append(df.format(cal.get(Calendar.SECOND)));
fitsDate.append(".");
df = new DecimalFormat("000");
fitsDate.append(df.format(cal.get(Calendar.MILLISECOND)));
}
return fitsDate.toString();
}
private int hour = -1;
private int mday = -1;
private int millisecond = -1;
private int minute = -1;
private int month = -1;
private int second = -1;
private int year = -1;
/**
* Convert a FITS date string to a Java Date object.
*
* @param dStr the FITS date
*
* @throws FitsException if dStr does not contain a valid FITS date.
*/
public FitsDate(String dStr) throws FitsException {
// if the date string is null, we are done
if (dStr == null || dStr.isEmpty()) {
return;
}
Matcher match = FitsDate.NORMAL_REGEX.matcher(dStr);
if (match.matches()) {
year = getInt(match, FitsDate.NEW_FORMAT_YEAR_GROUP);
month = getInt(match, FitsDate.NEW_FORMAT_MONTH_GROUP);
mday = getInt(match, FitsDate.NEW_FORMAT_DAY_OF_MONTH_GROUP);
hour = getInt(match, FitsDate.NEW_FORMAT_HOUR_GROUP);
minute = getInt(match, FitsDate.NEW_FORMAT_MINUTE_GROUP);
second = getInt(match, FitsDate.NEW_FORMAT_SECOND_GROUP);
millisecond = getMilliseconds(match, FitsDate.NEW_FORMAT_MILLISECOND_GROUP);
} else {
match = FitsDate.OLD_REGEX.matcher(dStr);
if (!match.matches()) {
if (dStr.trim().isEmpty()) {
return;
}
throw new FitsException("Bad FITS date string \"" + dStr + '"');
}
year = getInt(match, FitsDate.OLD_FORMAT_YEAR_GROUP) + FitsDate.YEAR_OFFSET;
month = getInt(match, FitsDate.OLD_FORMAT_MONTH_GROUP);
mday = getInt(match, FitsDate.OLD_FORMAT_DAY_OF_MONTH_GROUP);
}
}
private static int getInt(Matcher match, int groupIndex) {
String value = match.group(groupIndex);
if (value != null) {
return Integer.parseInt(value);
}
return -1;
}
private static int getMilliseconds(Matcher match, int groupIndex) {
String value = match.group(groupIndex);
if (value != null) {
value = String.format("%-3s", value).replace(' ', '0');
int num = Integer.parseInt(value);
if (value.length() > NB_DIGITS_MILLIS) {
num = (int) Math.round(num / Math.pow(POW_TEN, value.length() - NB_DIGITS_MILLIS));
}
return num;
}
return -1;
}
/**
* Get a Java Date object corresponding to this FITS date.
*
* @return The Java Date object.
*/
public Date toDate() {
if (year == -1) {
return null;
}
Calendar cal = Calendar.getInstance(UTC);
cal.set(Calendar.YEAR, year);
cal.set(Calendar.MONTH, month - 1);
cal.set(Calendar.DAY_OF_MONTH, mday);
if (hour == -1) {
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
} else {
cal.set(Calendar.HOUR_OF_DAY, hour);
cal.set(Calendar.MINUTE, minute);
cal.set(Calendar.SECOND, second);
if (millisecond == -1) {
cal.set(Calendar.MILLISECOND, 0);
} else {
cal.set(Calendar.MILLISECOND, millisecond);
}
}
return cal.getTime();
}
@Override
public String toString() {
if (year == -1) {
return "";
}
StringBuilder buf = new StringBuilder(FitsDate.FITS_DATE_STRING_SIZE);
buf.append(year);
buf.append('-');
appendTwoDigitValue(buf, month);
buf.append('-');
appendTwoDigitValue(buf, mday);
if (hour != -1) {
buf.append('T');
appendTwoDigitValue(buf, hour);
buf.append(':');
appendTwoDigitValue(buf, minute);
buf.append(':');
appendTwoDigitValue(buf, second);
if (millisecond != -1) {
buf.append('.');
appendThreeDigitValue(buf, millisecond);
}
}
return buf.toString();
}
@Override
public boolean equals(Object o) {
if (o == this) {
return true;
}
if (!(o instanceof FitsDate)) {
return false;
}
return compareTo((FitsDate) o) == 0;
}
@Override
public int hashCode() {
return Integer.hashCode(year) ^ Integer.hashCode(month) ^ Integer.hashCode(mday) ^ Integer.hashCode(hour)
^ Integer.hashCode(minute) ^ Integer.hashCode(second) ^ Integer.hashCode(millisecond);
}
@Override
public int compareTo(FitsDate fitsDate) {
int result = Integer.compare(year, fitsDate.year);
if (result != 0) {
return result;
}
result = Integer.compare(month, fitsDate.month);
if (result != 0) {
return result;
}
result = Integer.compare(mday, fitsDate.mday);
if (result != 0) {
return result;
}
result = Integer.compare(hour, fitsDate.hour);
if (result != 0) {
return result;
}
result = Integer.compare(minute, fitsDate.minute);
if (result != 0) {
return result;
}
result = Integer.compare(second, fitsDate.second);
if (result != 0) {
return result;
}
return Integer.compare(millisecond, fitsDate.millisecond);
}
private void appendThreeDigitValue(StringBuilder buf, int value) {
if (value < FitsDate.FIRST_THREE_CHARACTER_VALUE) {
buf.append('0');
}
appendTwoDigitValue(buf, value);
}
private void appendTwoDigitValue(StringBuilder buf, int value) {
if (value < FitsDate.FIRST_TWO_CHARACTER_VALUE) {
buf.append('0');
}
buf.append(value);
}
}
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