Solr ThreadLocal DateFormat - Open Source Code Snippet

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ThreadLocal DateFormat

private static class org.apache.solr.common.util.DateUtil.ThreadLocalDateFormat
   extends ThreadLocal<DateFormat> {
    DateFormat proto;
    public ThreadLocalDateFormat() {
      super();
      SimpleDateFormat tmp = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.ROOT);
      tmp.setTimeZone(UTC);
      proto = tmp;
    }
    protected DateFormat initialValue() {
      return (DateFormat) proto.clone();
    }
  }
  public static DateFormat getThreadLocalDateFormat() {
    return fmtThreadLocal.get();
  }
  private static ThreadLocalDateFormat fmtThreadLocal = new ThreadLocalDateFormat();

Support multiple date formats
org.apache.solr.common.util.DateUtil

static {
 DEFAULT_DATE_FORMATS.add("yyyy-MM-dd'T'HH:mm:ss'Z'");
 DEFAULT_DATE_FORMATS.add("yyyy-MM-dd'T'HH:mm:ss");
 DEFAULT_DATE_FORMATS.add("yyyy-MM-dd");
 DEFAULT_DATE_FORMATS.add("yyyy-MM-dd hh:mm:ss");
 DEFAULT_DATE_FORMATS.add("yyyy-MM-dd HH:mm:ss");
 DEFAULT_DATE_FORMATS.add("EEE MMM d hh:mm:ss z yyyy");
 DEFAULT_DATE_FORMATS.addAll(DEFAULT_HTTP_CLIENT_PATTERNS);
}
  
public static Date parseDate(String d, Collection<String> fmts) throws ParseException {
    if (d.endsWith("Z") && d.length() > 20) {
      return getThreadLocalDateFormat().parse(d);
    }
    return parseDate(d, fmts, null);
}
public static Date parseDate(String dateValue, Collection dateFormats, Date startDate) 
throws ParseException {
    Iterator formatIter = dateFormats.iterator();
    while (formatIter.hasNext()) {
      String format = (String) formatIter.next();
      if (dateParser == null) {
        dateParser = new SimpleDateFormat(format, Locale.ROOT);
        dateParser.setTimeZone(GMT);
        dateParser.set2DigitYearStart(startDate);
      } else {
        dateParser.applyPattern(format);
      }
      try {
        return dateParser.parse(dateValue);
      } catch (ParseException pe) {
        // ignore this exception, we will try the next format
      }
    }
}