public static final String formatDate(long value,
    DateFormat threadLocalformat) 
{
        Long longValue = new Long(value);
        String cachedDate = formatCache.get(longValue);
        if (cachedDate != null)
            return cachedDate;
        String newDate = null;
        Date dateValue = new Date(value);
        if (threadLocalformat != null) {
            newDate = threadLocalformat.format(dateValue);
            updateFormatCache(longValue, newDate);
        } else {
            synchronized (formatCache) {
                synchronized (format) {
                    newDate = format.format(dateValue);
                }
                updateFormatCache(longValue, newDate);
            }
        }
        return newDate;
}

Get the HTTP format of the specified date.

 public static final String getCurrentDate() 
{
        long now = System.currentTimeMillis();
        if ((now - currentDateGenerated)  > 1000) {
            synchronized (format) {
                if ((now - currentDateGenerated)  > 1000) {
                    currentDateGenerated = now;
                    currentDate = format.format(new Date(now));
                }
            }
        }
        return currentDate;
}

Get the current date in HTTP format.

 public static final long parseDate(String value,
    DateFormat[] threadLocalformats) 
{
        Long cachedDate = parseCache.get(value);
        if (cachedDate != null)
            return cachedDate.longValue();
        Long date = null;
        if (threadLocalformats != null) {
            date = internalParseDate(value, threadLocalformats);
            updateParseCache(value, date);
        } else {
            synchronized (parseCache) {
                date = internalParseDate(value, formats);
                updateParseCache(value, date);
            }
        }
        if (date == null) {
            return (-1L);
        } else {
            return date.longValue();
        }
}

Try to parse the given date as a HTTP date.