* This class does not take pattern strings. * It always formats the date based on the specification below. *
* 3.3 Date and Time Specification *
* Date and time occur in several header fields of a message. This section * specifies the syntax for a full date and time specification. Though folding * whitespace is permitted throughout the date-time specification, it is * recommended that only a single space be used where FWS is required and * no space be used where FWS is optional in the date-time specification; * some older implementations may not interpret other occurrences of folding * whitespace correctly. *
date-time = [ day-of-week "," ] date FWS time [CFWS]
day-of-week = ([FWS] day-name) / obs-day-of-week
day-name = "Mon" / "Tue" / "Wed" / "Thu" / "Fri" / "Sat" / "Sun"
date = day month year
year = 4*DIGIT / obs-year
month = (FWS month-name FWS) / obs-month
month-name = "Jan" / "Feb" / "Mar" / "Apr" /
"May" / "Jun" / "Jul" / "Aug" /
"Sep" / "Oct" / "Nov" / "Dec"
day = ([FWS] 1*2DIGIT) / obs-day
time = time-of-day FWS zone
time-of-day = hour ":" minute [ ":" second ]
hour = 2DIGIT / obs-hour
minute = 2DIGIT / obs-minute
second = 2DIGIT / obs-second
zone = (( "+" / "-" ) 4DIGIT) / obs-zone
* * The day is the numeric day of the month. * The year is any numeric year in the common era. *
* The time-of-day specifies the number of hours, minutes, and optionally * seconds since midnight of the date indicated. *
* The date and time-of-day SHOULD express local time. *
* The zone specifies the offset from Coordinated Universal Time (UTC, * formerly referred to as "Greenwich Mean Time") that the date and * time-of-day represent. * The "+" or "-" indicates whether the time-of-day is ahead of or behind * Universal Time. The first two digits indicate the number of hours' * difference from Universal Time, and the last two digits indicate the * number of minutes' difference from Universal Time. (Hence, +hhmm means * +(hh * 60 + mm) minutes, and -hhmm means -(hh * 60 + mm) minutes). * The form "+0000" SHOULD be used to indicate a time zone at Universal Time. * Though "-0000" also indicates Universal Time, it is used to indicate that * the time was generated on a system that may be in a local time zone other * than Universal Time. *
* A date-time specification MUST be semantically valid. * That is, the day-of-the week (if included) MUST be the day implied by * the date, the numeric day-of-month MUST be between 1 and the number of * days allowed for the specified month (in the specified year), the * time-of-day MUST be in the range 00:00:00 through 23:59:60 (the number * of seconds allowing for a leap second; see [STD-12]), and the zone MUST * be within the range -9959 through +9959. * * @author Chris Burdess * @version 1.3 */ public class MailDateFormat extends SimpleDateFormat { public MailDateFormat() { super("EEE, d MMM yyyy HH:mm:ss 'ZZZZZ'", Locale.US); //super("EEE, d MMM yyyy HH:mm:ss 'ZZZZZ' (z)", Locale.US); calendar = new GregorianCalendar(TimeZone.getTimeZone("GMT")); } /** * Formats the given date in the format specified by * draft-ietf-drums-msg-fmt-08 in the current TimeZone. * @param date the Date object * @param dateStrBuf the formatted string * @param fieldPosition the current field position */ public StringBuffer format(Date date, StringBuffer dateStrBuf, FieldPosition fieldPosition) { // Use super.format to do all but the pseudo time zone. int offset = dateStrBuf.length(); super.format(date, dateStrBuf, fieldPosition); // Advance pos to the beginning of the pseudo time zone field ZZZZZ int pos = offset+25; while (dateStrBuf.charAt(pos)!='Z') pos++; // get the time zone offset (in minutes) calendar.clear(); calendar.setTime(date); int zoneOffset = (calendar.get(Calendar.ZONE_OFFSET)+ calendar.get(Calendar.DST_OFFSET))/60000; // apply + or - appropriately if (zoneOffset<0) { zoneOffset = -zoneOffset; dateStrBuf.setCharAt(pos++, '-'); } else dateStrBuf.setCharAt(pos++, '+'); // set the 2 2-char fields as specified above int hours = zoneOffset/60; dateStrBuf.setCharAt(pos++, Character.forDigit(hours/10, 10)); dateStrBuf.setCharAt(pos++, Character.forDigit(hours%10, 10)); int minutes = zoneOffset%60; dateStrBuf.setCharAt(pos++, Character.forDigit(minutes/10, 10)); dateStrBuf.setCharAt(pos++, Character.forDigit(minutes%10, 10)); return dateStrBuf; } /** * Parses the given date in the format specified by * draft-ietf-drums-msg-fmt-08 in the current TimeZone. * @param text the formatted date to be parsed * @param pos the current parse position */ public Date parse(String text, ParsePosition pos) { // strip out the timezone (ZZZZZ) field if it exists // there can't be a + or - until that field int zoneOffset = 0; int start = text.indexOf('+'); if (start<0) start = text.indexOf('-'); if (start>-1) { StringBuffer buffer = new StringBuffer(); buffer.append(text.substring(0, start)); int end = text.indexOf(' ', start+1); if (end==(start+5)) { buffer.append(text.substring(end)); char pm = text.charAt(start++); zoneOffset += 600*Character.digit(text.charAt(start++), 10); zoneOffset += 60*Character.digit(text.charAt(start++), 10); zoneOffset += 10*Character.digit(text.charAt(start++), 10); zoneOffset += Character.digit(text.charAt(start++), 10); zoneOffset *= 60000; if ('-'==pm) zoneOffset = -zoneOffset; } text = buffer.toString(); } Date date = super.parse(text, pos); // Use the zoneOffset to compensate as raw offset // as there is no way to determine the DST part if (date!=null) { calendar.clear(); calendar.setTime(date); calendar.set(Calendar.ZONE_OFFSET, zoneOffset); date = calendar.getTime(); } return date; } /** * Don't allow setting the calendar. */ public void setCalendar(Calendar newCalendar) { throw new RuntimeException("Method not available"); } /** * Don't allow setting the NumberFormat. */ public void setNumberFormat(NumberFormat newNumberFormat) { throw new RuntimeException("Method not available"); } }