/* * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/util/DateUtil.java,v 1.2 2004/12/24 20:36:13 olegk Exp $ * $Revision: 480424 $ * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $ * * ==================================================================== * *  Licensed to the Apache Software Foundation (ASF) under one or more *  contributor license agreements.  See the NOTICE file distributed with *  this work for additional information regarding copyright ownership. *  The ASF licenses this file to You under the Apache License, Version 2.0 *  (the "License"); you may not use this file except in compliance with *  the License.  You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * *  Unless required by applicable law or agreed to in writing, software *  distributed under the License is distributed on an "AS IS" BASIS, *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *  See the License for the specific language governing permissions and *  limitations under the License. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation.  For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */package org.apache.commons.httpclient.util;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Arrays;import java.util.Calendar;import java.util.Collection;import java.util.Date;import java.util.Iterator;import java.util.Locale;import java.util.TimeZone;/** * A utility class for parsing and formatting HTTP dates as used in cookies and  * other headers.  This class handles dates as defined by RFC 2616 section  * 3.3.1 as well as some other common non-standard formats. *  * @author Christopher Brown * @author Michael Becke */public class DateUtil {    /**     * Date format pattern used to parse HTTP date headers in RFC 1123 format.     */    public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";    /**     * Date format pattern used to parse HTTP date headers in RFC 1036 format.     */    public static final String PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";    /**     * Date format pattern used to parse HTTP date headers in ANSI C      * <code>asctime()</code> format.     */    public static final String PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";    private static final Collection DEFAULT_PATTERNS = Arrays.asList(            new String[] { PATTERN_ASCTIME, PATTERN_RFC1036, PATTERN_RFC1123 } );        private static final Date DEFAULT_TWO_DIGIT_YEAR_START;        static {        Calendar calendar = Calendar.getInstance();        calendar.set(2000, Calendar.JANUARY, 1, 0, 0);        DEFAULT_TWO_DIGIT_YEAR_START = calendar.getTime();     }        private static final TimeZone GMT = TimeZone.getTimeZone("GMT");        /**     * Parses a date value.  The formats used for parsing the date value are retrieved from     * the default http params.     *     * @param dateValue the date value to parse     *      * @return the parsed date     *     * @throws DateParseException if the value could not be parsed using any of the      * supported date formats     */    public static Date parseDate(String dateValue) throws DateParseException {        return parseDate(dateValue, null, null);    }        /**     * Parses the date value using the given date formats.     *      * @param dateValue the date value to parse     * @param dateFormats the date formats to use     *      * @return the parsed date     *      * @throws DateParseException if none of the dataFormats could parse the dateValue     */    public static Date parseDate(String dateValue, Collection dateFormats)         throws DateParseException {        return parseDate(dateValue, dateFormats, null);    }        /**     * Parses the date value using the given date formats.     *      * @param dateValue the date value to parse     * @param dateFormats the date formats to use     * @param startDate During parsing, two digit years will be placed in the range      * <code>startDate</code> to <code>startDate + 100 years</code>. This value may      * be <code>null</code>. When <code>null</code> is given as a parameter, year      * <code>2000</code> will be used.      *      * @return the parsed date     *      * @throws DateParseException if none of the dataFormats could parse the dateValue     */    public static Date parseDate(        String dateValue,         Collection dateFormats,        Date startDate     ) throws DateParseException {                if (dateValue == null) {            throw new IllegalArgumentException("dateValue is null");        }        if (dateFormats == null) {            dateFormats = DEFAULT_PATTERNS;        }        if (startDate == null) {            startDate = DEFAULT_TWO_DIGIT_YEAR_START;        }        // trim single quotes around date if present        // see issue #5279        if (dateValue.length() > 1             && dateValue.startsWith("'")             && dateValue.endsWith("'")        ) {            dateValue = dateValue.substring (1, dateValue.length() - 1);        }                SimpleDateFormat dateParser = null;                Iterator formatIter = dateFormats.iterator();                while (formatIter.hasNext()) {            String format = (String) formatIter.next();                        if (dateParser == null) {                dateParser = new SimpleDateFormat(format, Locale.US);                dateParser.setTimeZone(TimeZone.getTimeZone("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            }                        }                // we were unable to parse the date        throw new DateParseException("Unable to parse the date " + dateValue);            }    /**     * Formats the given date according to the RFC 1123 pattern.     *      * @param date The date to format.     * @return An RFC 1123 formatted date string.     *      * @see #PATTERN_RFC1123     */    public static String formatDate(Date date) {        return formatDate(date, PATTERN_RFC1123);    }        /**     * Formats the given date according to the specified pattern.  The pattern     * must conform to that used by the {@link SimpleDateFormat simple date     * format} class.     *      * @param date The date to format.     * @param pattern The pattern to use for formatting the date.       * @return A formatted date string.     *      * @throws IllegalArgumentException If the given date pattern is invalid.     *      * @see SimpleDateFormat     */    public static String formatDate(Date date, String pattern) {        if (date == null) throw new IllegalArgumentException("date is null");        if (pattern == null) throw new IllegalArgumentException("pattern is null");                SimpleDateFormat formatter = new SimpleDateFormat(pattern, Locale.US);        formatter.setTimeZone(GMT);        return formatter.format(date);    }        /** This class should not be instantiated. */        private DateUtil() { }    }