InternetDateFormat for RFC3339

Java isn't supported RFC3339.

Because I made InternetDateFormat class.

But it hasn't tested very much.

If you use this class, you need a few test.

	import java.text.DateFormat;
	import java.text.FieldPosition;
	import java.text.NumberFormat;
	import java.text.ParsePosition;
	import java.util.Calendar;
	import java.util.Date;
	import java.util.Locale;
	import java.util.TimeZone;
	/**
	* InternetDateFormat is supported RFC3339.
	* e.g. "1937-01-01T12:00:27.87+00:20"
	* Because SimpleDateFormat can't parse or format to RFC3339.
	* InternetDateFormat not invoke performance tuning, perhaps it is slowly.
	* @version 1.14
	* @author Bladean Mericle
	*/
	public class InternetDateFormat extends DateFormat {
	/** Auto generated serialVersionUID. */
	private static final long serialVersionUID = -3948472717995863848L;
	/** Date/time formatting with time offset. */
	protected boolean zoneOffsetFlagField = true;
	/** Fractional seconds digits. */
	protected int fractionalSecondsLengthField = 0;
	/**
	* Default constructor.
	* Output time offset, and not output fractional seconds.
	*/
	public InternetDateFormat() {
	super();
	setCalendar(Calendar.getInstance());
	setNumberFormat(NumberFormat.getInstance());
	}
	/**
	* Constructor.
	* @param zone the given new time zone.
	* @param aLocale the given locale.
	*/
	public InternetDateFormat(TimeZone zone, Locale aLocale) {
	super();
	setCalendar(Calendar.getInstance(zone, aLocale));
	setNumberFormat(NumberFormat.getInstance(aLocale));
	}
	/**
	* Constructor.
	* @param anOffset date/time formatting with time offset
	* @param aFractionalSecondsDigits fractional seconds digits (0-3)
	*/
	public InternetDateFormat(
	boolean zoneOffsetFlag,
	int fractionalSecondsLength) {
	this();
	setZoneOffset(zoneOffsetFlag);
	setFractionalSecondsLength(fractionalSecondsLength);
	}
	/**
	* Constructor.
	* @param zone the given new time zone.
	* @param aLocale the given locale.
	* @param anOffset date/time formatting with time offset
	* @param aFractionalSecondsDigits fractional seconds digits (0-3)
	*/
	public InternetDateFormat(
	TimeZone zone,
	Locale aLocale,
	boolean zoneOffsetFlag,
	int fractionalSecondsLength) {
	this(zone, aLocale);
	setZoneOffset(zoneOffsetFlag);
	setFractionalSecondsLength(fractionalSecondsLength);
	}
	/**
	* Tell whether date/time formatting with time offset.
	* The offset is used only format method.
	* @return true is formatting with time offset; false otherwise.
	*/
	public boolean hasZoneOffset() {
	return zoneOffsetFlagField;
	}
	/**
	* Specify whether or not date/time formatting with time offset.
	* The offset is used only format method.
	* @param anOffset true is formatting with time offset; false otherwise.
	*/
	public void setZoneOffset(boolean zoneOffsetFlag) {
	zoneOffsetFlagField = zoneOffsetFlag;
	}
	/**
	* Gets the number of fractional seconds digits.
	* The digits is used only format method.
	* @return fractional seconds digits (0-3)
	*/
	public int getFractionalSecondsLength() {
	return fractionalSecondsLengthField;
	}
	/**
	* Sets the number of fractional seconds digits.
	* Digits range is 0 to 3.
	* If digits over range, this method throws IllegalArgumentException.
	* The digits is used only format method.
	* @param fractionalSecondsDigits fractional seconds digits (0-3)
	*/
	public void setFractionalSecondsLength(int fractionalSecondsLength) {
	if (fractionalSecondsLength < 0 || 3 < fractionalSecondsLength) {
	throw new IllegalArgumentException(
	"Invalid fractional seconds length(" + fractionalSecondsLength + ")");
	}
	fractionalSecondsLengthField = fractionalSecondsLength;
	}
	/**
	* Formats a Date into a date/time string.
	* @param date a Date to be formatted into a date/time string.
	* @param toAppendTo the string buffer for the returning time string.
	* @param fieldPosition keeps track of the position of the field within the returned string.
	*/
	@Override
	public StringBuffer format(
	Date date,
	StringBuffer toAppendTo,
	FieldPosition fieldPosition) {
	Calendar calendar = (Calendar) getCalendar().clone();
	calendar.setTime(date);
	if (hasZoneOffset()) {
	int offset = calendar.get(Calendar.ZONE_OFFSET);
	toAppendTo.append(String.format(
	"%1$tFT%1$tH:%1$tM:%1$tS", calendar.getTime()));
	toAppendTo.append(getFractionalSeconds(calendar));
	toAppendTo.append((offset >= 0) ? "+" : "-");
	toAppendTo.append(String.format(
	"%1$02d:%2$02d",
	offset / 3600000,
	offset % 3600000 / 1000));
	} else {
	// タイムゾーンオフセットの補正
	calendar.add(Calendar.MILLISECOND, -calendar.get(Calendar.ZONE_OFFSET));
	toAppendTo.append(String.format(
	"%1$tFT%1$tH:%1$tM:%1$tS", calendar.getTime()));
	toAppendTo.append(getFractionalSeconds(calendar));
	toAppendTo.append("Z");
	}
	return toAppendTo;
	}
	/***
	* Formats a Date into a fractional seconds string.
	* @param formatCalendar be formatted date
	* @return fractional seconds string
	*/
	protected String getFractionalSeconds(Calendar calendar) {
	if (getFractionalSecondsLength() == 0) { return ""; }
	return "." + String.format(
	"%03d",
	calendar.get(Calendar.MILLISECOND)).substring(
	0,
	getFractionalSecondsLength());
	}
	/**
	* Parse a date/time string according to the given parse position.
	* @param source The date/time string to be parsed
	* @param pos the parsing position
	* the position at which parsing terminated, or the start position if the parse failed.
	*/
	@Override
	public Date parse(String source, ParsePosition pos) {
	try {
	Calendar calendar = (Calendar) getCalendar().clone();
	calendar.set(Calendar.YEAR, parseNumber(source, pos, 4));
	checkSeparator(source, pos, "-");
	calendar.set(Calendar.MONTH, parseNumber(source, pos, 2) - 1);
	checkSeparator(source, pos, "-");
	calendar.set(Calendar.DAY_OF_MONTH, parseNumber(source, pos, 2));
	checkSeparator(source, pos, "T");
	calendar.set(Calendar.HOUR_OF_DAY, parseNumber(source, pos, 2));
	checkSeparator(source, pos, ":");
	calendar.set(Calendar.MINUTE, parseNumber(source, pos, 2));
	checkSeparator(source, pos, ":");
	calendar.set(Calendar.SECOND, parseNumber(source, pos, 2));
	if (source.substring(pos.getIndex()).startsWith(".")) {
	pos.setIndex(pos.getIndex() + 1);
	calendar.set(Calendar.MILLISECOND, parseFractionalSeconds(source, pos));
	} else {
	calendar.set(Calendar.MILLISECOND, 0);
	}
	String next = source.substring(pos.getIndex());
	if (next.equals("Z")) {
	pos.setIndex(pos.getIndex() + 1);
	calendar.set(Calendar.ZONE_OFFSET, 0); // 省略時は00:00と等価
	return calendar.getTime();
	} else if (next.startsWith("+")) {
	pos.setIndex(pos.getIndex() + 1);
	calendar.set(Calendar.ZONE_OFFSET, parseZoneOffset(source, pos));
	return calendar.getTime();
	} else if (next.startsWith("-")) {
	pos.setIndex(pos.getIndex() + 1);
	calendar.set(Calendar.ZONE_OFFSET, -parseZoneOffset(source, pos));
	return calendar.getTime();
	}
	pos.setErrorIndex(pos.getIndex());
	return null;
	} catch (IndexOutOfBoundsException e) {
	pos.setErrorIndex(pos.getIndex());
	return null;
	}
	}
	/**
	* Parse number, and increment parse position.
	* @param source A String whose beginning should be parsed.
	* @param pos the parsing position
	* @param length parse length
	* @return parsed number
	*/
	protected int parseNumber(
	String source,
	ParsePosition pos,
	int length) {
	int index = pos.getIndex();
	int number = Integer.parseInt(source.substring(index, index + length));
	pos.setIndex(index + length);
	return number;
	}
	/**
	* Check separator string is valid.
	* If separetaor is invalid, this method throws IndexOutOfBoundsException.
	* @param source A String whose beginning should be parsed.
	* @param pos the parsing position
	* @param separator separator string
	*/
	protected void checkSeparator(
	String source,
	ParsePosition pos,
	String separator) {
	int index = pos.getIndex();
	int length = separator.length();
	if (!source.substring(index, index + length).equals(separator)) {
	throw new IndexOutOfBoundsException();
	}
	pos.setIndex(index + length);
	}
	/**
	* Parse fractional seconds.
	* @param source A String whose beginning should be parsed.
	* @param pos the parsing position
	* @return parsed fractional seconds
	*/
	protected int parseFractionalSeconds(String source, ParsePosition pos) {
	String milliSecond = source.substring(pos.getIndex()).split("\\D")[0];
	int number = Integer.parseInt((milliSecond + "000").substring(0, 3));
	pos.setIndex(pos.getIndex() + milliSecond.length());
	return number;
	}
	/**
	* Parse offset.
	* But it is not include "+" or "-".
	* When this method is called, these operator have to be already parsed.
	* @param source A String whose beginning should be parsed.
	* @param pos the parsing position
	* @return offset millisecond
	*/
	protected int parseZoneOffset(
	String source,
	ParsePosition pos) {
	int hour = parseNumber(source, pos, 2);
	checkSeparator(source, pos, ":");
	int minute = parseNumber(source, pos, 2);
	return (hour * 60 + minute) * 60000;
	}
	}

view raw InternetDateFormat.java hosted with ❤ by GitHub

	import java.text.ParseException;
	import java.util.Date;
	public class InternetDateFormatSample {
	public static void main(String[] args) {
	try {
	InternetDateFormat format = new InternetDateFormat();
	System.out.println(format.format(new Date()));
	System.out.println(format.parse("2013-07-04T19:52:42+09:00"));
	format.setZoneOffset(false);
	System.out.println(format.format(new Date()));
	format.setFractionalSecondsLength(2);
	System.out.println(format.format(new Date()));
	} catch (ParseException e) {
	e.printStackTrace();
	}
	}
	}

view raw InternetDateFormatSample.java hosted with ❤ by GitHub

FYI:Japanese Edition

2013/07/31: Update detail.
2013/12/16: Bug fix "parseFractionalSeconds".
2017/09/18: Bug fix "parse" (Thanka comment!)