simpledateformat.java

kaffe是一个java虚拟机的源代码。里面包含了一些java例程和标准的java包。

	int startIndex = pos.getIndex();
	int index = startIndex;
	int endIndex = source.length();

	int tzStart = -1, tzEnd = -1;

	char[] patt = pattern.toCharArray();
	for (int i = 0; i < patt.length; ) {
		char letter = patt[i++];

		if (letter == '\'') {
			// quoted text
			if ((i < patt.length) && (patt[i] == '\'')) {
				if ((index >= endIndex) ||
				    (source.charAt(index) != '\'')) {
					pos.setIndex(startIndex);
					pos.setErrorIndex(index);
					return null;
				}
				index++;
				i++;
			}
			else {
				boolean done = false, error = false;

				while (!done &&
				       !error &&
				       (i < patt.length) &&
				       (index < endIndex) ) {
					switch (patt[i]) {
					case '\'':
						if (((i + 1) < patt.length) &&
						    (patt[i + 1] == '\'')) {
							if (source.charAt(index) == '\'') {
								index++;
								i++;
							} else {
								System.out.println("hello - " + i + " " + index);
								error = true;
							}
						} else {
							done = true;
						}
						break;
					default:
						if( source.charAt(index) !=
						    patt[i] ) {
							System.out.println("hello 2 - " + i + " " + index);
							error = true;
						}
						index++;
						break;
					}
					i++;
				}
				if( error || (index >= endIndex) )
				{
					pos.setIndex(startIndex);
					pos.setErrorIndex(index);
					return null;
				}
				while ((i < patt.length) && patt[i] != '\'') {
					if ((index >= endIndex) ||
					    (source.charAt(index) != patt[i])) {
						pos.setIndex(startIndex);
						pos.setErrorIndex(index);
						return null;
					}
					index++;
					i++;
				}
				i++;
			}
		}
		else if (((letter >= 'a') && (letter <= 'z')) ||
			 ((letter >= 'A') && (letter <= 'Z'))) {
			// pattern Code
			int plen = 1;
			int val = -1;
			
			// count pattern len
			while ((i < patt.length) && (patt[i] == letter)) {
				plen++;
				i++;
			}
			
			// skip blanks
			for (;;) {
				if (index >= endIndex) {
					pos.setIndex(startIndex);
					pos.setErrorIndex(index);
					return null;
				}
				char c = source.charAt(index);
				if ((c != ' ') && (c != '\t'))
					break;
				index++;
			}
			pos.setIndex(index);

			// handle numeric values
			if ((NUMERIC_PATTERN.indexOf(letter) != -1) ||
			    ((letter == 'M') && (plen <= 2))) {
				Number number;
				if ((i < patt.length) &&
				    (DEFAULTPATTERNCHARS.indexOf(patt[i]) != -1)) {
					if (index + plen > endIndex) {
						pos.setIndex(startIndex);
						pos.setErrorIndex(index);
						return null;
					}
					number = numberFormat.parse(source.substring(0, index + plen), pos);
				}
				else {
					number = numberFormat.parse(source, pos);
				}
				if (number == null) {
					pos.setIndex(startIndex);
					pos.setErrorIndex(index);
					return null;
				}
				val = number.intValue();
				switch (letter) {
				case 'y':
					// 2 digits and only 2 digits
					if( (plen < 3) &&
					    (val >= 0) &&
					    (pos.getIndex() - index <= 2) )
					{
						// The year is ambiguous,
						// adjust century to be within
						// 80 years before and 20 years
						// after current time
						int current = Calendar.getInstance().get(Calendar.YEAR);
						int epoch = current - current % 100;
						int year = epoch + val;
						
						if (year > current + 20)
							year -= 100;
						else if (year < current - 80)
							year += 100;
						val = year;
					}
					break;
				case 'M':
					val--;
					break;
				case 'k':
					if (val == 24)
						val = 0;
					break;
				case 'h':
					if (val == 12)
						val = 0;
					break;
				}
				calendar.set (NUMERIC_FIELD[NUMERIC_PATTERN.indexOf(letter) + 1],
					      val);
				index = pos.getIndex();
			}
			// handle strings values
			else {
				switch (letter) {
				case 'G':
					index = parseField (source, index, Calendar.ERA, syms.eras);
					break;
				case 'M':
					index = parseField (source, index, Calendar.MONTH, syms.months);
					if (index <= 0)
						index = parseField (source, -index, Calendar.MONTH, syms.shortMonths);
					break;
				case 'E':
					index = parseField (source, index, Calendar.DAY_OF_WEEK, syms.weekdays);
					if (index <= 0)
						index = parseField (source, -index, Calendar.DAY_OF_WEEK, syms.shortWeekdays);
					break;
				case 'a':
					index = parseField (source, index, Calendar.AM_PM, syms.amPmStrings);
					break;
				case 'z':
					tzStart = index;
					index = parseTimeZone (source, index, endIndex);
					tzEnd = index;
					break;
				default:
					index = -index;
				}
				if (index <= 0) {
					pos.setIndex(startIndex);
					pos.setErrorIndex(-index);
					return null;
				}
				pos.setIndex(index);
			}
		}
		else {
			// match literal
			if ((index >= endIndex) ||
			    (source.charAt(index) != letter)) {
				pos.setIndex(startIndex);
				pos.setErrorIndex(index);
				return null;
			}
			index++;
		}
	}

	if( tzStart != -1 )
	{
		// We have all the info we're gonna get, patch up the
		// the time zone.
		reallyParseTimeZone(source, tzStart, tzEnd);
	}
	pos.setIndex (index);
	return calendar.getTime();
}

private int parseField (String source, int start, int field, String[] data) {
	int best = -1;
	int bestLen = 0;
	
	for (int i = data.length; i-- > 0; ) {
		int len = data[i].length();
		if ((len > bestLen) &&
		    source.regionMatches (true, start, data[i], 0, len)) {
			best = i;
			bestLen = len;
		}
	}

	if (best >= 0) {
		calendar.set (field, best);
		return start + bestLen;
	}
	return -start;
}

private void reallyParseTimeZone (String source, int start, int endIndex) {
	
	if (source.regionMatches (start, "GMT", 0, 3)) {
		// GMT +/- ##:##, `should' work fine.
		return;
	}

	// Redo localized if it applies
	int bestZone = -1;
	int bestLen = 0;
	int bestType = 0;
	for (int i = 0; i < syms.zoneStrings.length; i++) {
		String[] zone = syms.zoneStrings[i];

		for (int j = 1; j <= 4; j++) {
			int len = zone[j].length();

			if ((len > bestLen) &&
			    source.regionMatches (true, start, zone[j], 0, len)) {
				bestZone = i;
				bestType = j;
				bestLen = len;
			}
		}
	}
	if (bestZone != -1) {
		TimeZone tz = TimeZone.getTimeZone (syms.zoneStrings[bestZone][bestType]);
		long offset;

		// Get the real offset, including DST adjustments.
		offset = tz.getOffset(calendar.get(Calendar.ERA),
				      calendar.get(Calendar.YEAR),
				      calendar.get(Calendar.MONTH),
				      calendar.get(Calendar.DAY_OF_MONTH),
				      calendar.get(Calendar.DAY_OF_WEEK),
				      calendar.get(Calendar.MILLISECOND));
		calendar.set(Calendar.ZONE_OFFSET, (int)offset);
		return;
	}

	// its RFC 822 +hhmm format
	return;
}

private int parseTimeZone (String source, int start, int endIndex) {
	// XXX better handle DST_OFFSET if tz.useDaylightTime() ?
	calendar.set(Calendar.DST_OFFSET, 0);

	if (source.regionMatches (start, "GMT", 0, 3)) {
		int index = start + 3;
		int sign = 0;

		if (index < endIndex) {
			switch (source.charAt(index)) {
			case '+':
				sign = +1;
				break;
			case '-':
				sign = -1;
			}
		}
		if (sign == 0) {
			calendar.set(Calendar.ZONE_OFFSET, 0);
			return index;
		}

		ParsePosition pos = new ParsePosition(index + 1);
		Number num = numberFormat.parse (source, pos);
		if (num == null)
			return -start;
		int offset = num.intValue();
		if ((pos.getIndex() < endIndex) &&
		    (source.charAt(pos.getIndex()) == ':')) {
			// GMT+hh:mm
			offset *= 60;
			pos.setIndex(pos.getIndex() + 1);
			num = numberFormat.parse (source, pos);
			if (num == null)
				return -start;
			offset += num.intValue();
		}
		else {
			// GMT+hh[mm]
			if (offset < 24)
				offset *= 60;
			else
				offset = (offset / 100) * 60 + offset % 100;
		}
		offset *= 60 * 1000;
		if (sign == -1)
			offset = -offset;
		calendar.set(Calendar.ZONE_OFFSET, offset);
		return pos.getIndex();
	}

	// search localized timezone
	int bestZone = -1;
	int bestLen = 0;
	int bestType = 0;
	for (int i = 0; i < syms.zoneStrings.length; i++) {
		String[] zone = syms.zoneStrings[i];

		for (int j = 1; j <= 4; j++) {
			int len = zone[j].length();

			if ((len > bestLen) &&
			    source.regionMatches (true, start, zone[j], 0, len)) {
				bestZone = i;
				bestType = j;
				bestLen = len;
			}
		}
	}
	if (bestZone != -1) {
		TimeZone tz = TimeZone.getTimeZone (syms.zoneStrings[bestZone][bestType]);
		// XXX Ugh, this is messy...  Basically, we can't tell whether
		// DST applies or not, so we have to wait till later to
		// figure it out.
		calendar.set(Calendar.ZONE_OFFSET, 0);
		return start + bestLen;
	}

	// try RFC 822 +hhmm format
	DecimalFormat rfc822 = new DecimalFormat("+####;-####");
	rfc822.setParseIntegerOnly(true);
	rfc822.setGroupingUsed(false);
	ParsePosition pos = new ParsePosition (start);
	Number num = rfc822.parse (source, pos);
	if (num == null)
		return -start;

	int offset = num.intValue();
	int sign = 1;
	if (offset < 0) {
		sign = -1;
		offset = -offset;
	}
	if (offset < 24)
		offset *= 60;
	else
		offset = (offset / 100) * 60 + offset % 100;

	offset *= 60 * 1000;
	if (sign == -1)
		offset = -offset;
	calendar.set(Calendar.ZONE_OFFSET, offset);
	return pos.getIndex();
}

public void setDateFormatSymbols(DateFormatSymbols syms) {
	this.syms = syms;
}

public String toLocalizedPattern() {
	StringBuffer buf = new StringBuffer();
	String locals = syms.getLocalPatternChars();

	for (int i = 0; i < pattern.length(); i++) {
		int idx = DEFAULTPATTERNCHARS.indexOf(pattern.charAt(i));
		if (idx >= 0) {
			buf.append(locals.charAt(idx));
		}
		else {
			buf.append(pattern.charAt(i));
		}
	}

	return (buf.toString());
}

public String toPattern() {
	return (pattern);
}
}