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package org.glassfish.jersey.message.internal;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Collections;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.TimeZone;
/**
* Helper class for HTTP specified date formats.
*
* @author Paul Sandoz
* @author Marek Potociar (marek.potociar at oracle.com)
*/
public final class HttpDateFormat {
private HttpDateFormat() {
}
/**
* The date format pattern for RFC 1123.
*/
private static final String RFC1123_DATE_FORMAT_PATTERN = "EEE, dd MMM yyyy HH:mm:ss zzz";
/**
* The date format pattern for RFC 1036.
*/
private static final String RFC1036_DATE_FORMAT_PATTERN = "EEEE, dd-MMM-yy HH:mm:ss zzz";
/**
* The date format pattern for ANSI C asctime().
*/
private static final String ANSI_C_ASCTIME_DATE_FORMAT_PATTERN = "EEE MMM d HH:mm:ss yyyy";
private static final TimeZone GMT_TIME_ZONE = TimeZone.getTimeZone("GMT");
private static final ThreadLocal> dateFormats = new ThreadLocal>() {
@Override
protected synchronized List initialValue() {
return createDateFormats();
}
};
private static List createDateFormats() {
final SimpleDateFormat[] formats = new SimpleDateFormat[]{
new SimpleDateFormat(RFC1123_DATE_FORMAT_PATTERN, Locale.US),
new SimpleDateFormat(RFC1036_DATE_FORMAT_PATTERN, Locale.US),
new SimpleDateFormat(ANSI_C_ASCTIME_DATE_FORMAT_PATTERN, Locale.US)
};
formats[0].setTimeZone(GMT_TIME_ZONE);
formats[1].setTimeZone(GMT_TIME_ZONE);
formats[2].setTimeZone(GMT_TIME_ZONE);
return Collections.unmodifiableList(Arrays.asList(formats));
}
/**
* Return an unmodifiable list of HTTP specified date formats to use for
* parsing or formatting {@link Date}.
*
* The list of date formats are scoped to the current thread and may be
* used without requiring to synchronize access to the instances when
* parsing or formatting.
*
* @return the list of data formats.
*/
private static List getDateFormats() {
return dateFormats.get();
}
/**
* Get the preferred HTTP specified date format (RFC 1123).
*
* The date format is scoped to the current thread and may be
* used without requiring to synchronize access to the instance when
* parsing or formatting.
*
* @return the preferred of data format.
*/
public static SimpleDateFormat getPreferredDateFormat() {
// returns clone because calling SDF.parse(...) can change time zone
return (SimpleDateFormat) dateFormats.get().get(0).clone();
}
/**
* Read a date.
*
* @param date the date as a string.
*
* @return the date
* @throws java.text.ParseException in case the date string cannot be parsed.
*/
public static Date readDate(final String date) throws ParseException {
ParseException pe = null;
for (final SimpleDateFormat f : HttpDateFormat.getDateFormats()) {
try {
Date result = f.parse(date);
// parse can change time zone -> set it back to GMT
f.setTimeZone(GMT_TIME_ZONE);
return result;
} catch (final ParseException e) {
pe = (pe == null) ? e : pe;
}
}
throw pe;
}
}