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Java > Open Source Codes > org > apache > commons > httpclient > util > DateUtil


1 /*
2  * $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 $
3  * $Revision: 480424 $
4  * $Date: 2006-11-29 05:56:49 +0000 (Wed, 29 Nov 2006) $
5  *
6  * ====================================================================
7  *
8  * Licensed to the Apache Software Foundation (ASF) under one or more
9  * contributor license agreements. See the NOTICE file distributed with
10  * this work for additional information regarding copyright ownership.
11  * The ASF licenses this file to You under the Apache License, Version 2.0
12  * (the "License"); you may not use this file except in compliance with
13  * the License. You may obtain a copy of the License at
14  *
15  * http://www.apache.org/licenses/LICENSE-2.0
16  *
17  * Unless required by applicable law or agreed to in writing, software
18  * distributed under the License is distributed on an "AS IS" BASIS,
19  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
20  * See the License for the specific language governing permissions and
21  * limitations under the License.
22  * ====================================================================
23  *
24  * This software consists of voluntary contributions made by many
25  * individuals on behalf of the Apache Software Foundation. For more
26  * information on the Apache Software Foundation, please see
27  * <http://www.apache.org/>.
28  *
29  */
30
31 package org.apache.commons.httpclient.util;
32
33 import java.text.ParseException JavaDoc;
34 import java.text.SimpleDateFormat JavaDoc;
35 import java.util.Arrays JavaDoc;
36 import java.util.Calendar JavaDoc;
37 import java.util.Collection JavaDoc;
38 import java.util.Date JavaDoc;
39 import java.util.Iterator JavaDoc;
40 import java.util.Locale JavaDoc;
41 import java.util.TimeZone JavaDoc;
42
43 /**
44  * A utility class for parsing and formatting HTTP dates as used in cookies and
45  * other headers. This class handles dates as defined by RFC 2616 section
46  * 3.3.1 as well as some other common non-standard formats.
47  *
48  * @author Christopher Brown
49  * @author Michael Becke
50  */
51 public class DateUtil {
52
53     /**
54      * Date format pattern used to parse HTTP date headers in RFC 1123 format.
55      */
56     public static final String JavaDoc PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";
57
58     /**
59      * Date format pattern used to parse HTTP date headers in RFC 1036 format.
60      */
61     public static final String JavaDoc PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";
62
63     /**
64      * Date format pattern used to parse HTTP date headers in ANSI C
65      * <code>asctime()</code> format.
66      */
67     public static final String JavaDoc PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";
68
69     private static final Collection JavaDoc DEFAULT_PATTERNS = Arrays.asList(
70             new String JavaDoc[] { PATTERN_ASCTIME, PATTERN_RFC1036, PATTERN_RFC1123 } );
71     
72     private static final Date JavaDoc DEFAULT_TWO_DIGIT_YEAR_START;
73     
74     static {
75         Calendar JavaDoc calendar = Calendar.getInstance();
76         calendar.set(2000, Calendar.JANUARY, 1, 0, 0);
77         DEFAULT_TWO_DIGIT_YEAR_START = calendar.getTime();
78     }
79     
80     private static final TimeZone JavaDoc GMT = TimeZone.getTimeZone("GMT");
81     
82     /**
83      * Parses a date value. The formats used for parsing the date value are retrieved from
84      * the default http params.
85      *
86      * @param dateValue the date value to parse
87      *
88      * @return the parsed date
89      *
90      * @throws DateParseException if the value could not be parsed using any of the
91      * supported date formats
92      */
93     public static Date JavaDoc parseDate(String JavaDoc dateValue) throws DateParseException {
94         return parseDate(dateValue, null, null);
95     }
96     
97     /**
98      * Parses the date value using the given date formats.
99      *
100      * @param dateValue the date value to parse
101      * @param dateFormats the date formats to use
102      *
103      * @return the parsed date
104      *
105      * @throws DateParseException if none of the dataFormats could parse the dateValue
106      */
107     public static Date JavaDoc parseDate(String JavaDoc dateValue, Collection JavaDoc dateFormats)
108         throws DateParseException {
109         return parseDate(dateValue, dateFormats, null);
110     }
111     
112     /**
113      * Parses the date value using the given date formats.
114      *
115      * @param dateValue the date value to parse
116      * @param dateFormats the date formats to use
117      * @param startDate During parsing, two digit years will be placed in the range
118      * <code>startDate</code> to <code>startDate + 100 years</code>. This value may
119      * be <code>null</code>. When <code>null</code> is given as a parameter, year
120      * <code>2000</code> will be used.
121      *
122      * @return the parsed date
123      *
124      * @throws DateParseException if none of the dataFormats could parse the dateValue
125      */
126     public static Date JavaDoc parseDate(
127         String JavaDoc dateValue,
128         Collection JavaDoc dateFormats,
129         Date JavaDoc startDate
130     ) throws DateParseException {
131         
132         if (dateValue == null) {
133             throw new IllegalArgumentException JavaDoc("dateValue is null");
134         }
135         if (dateFormats == null) {
136             dateFormats = DEFAULT_PATTERNS;
137         }
138         if (startDate == null) {
139             startDate = DEFAULT_TWO_DIGIT_YEAR_START;
140         }
141         // trim single quotes around date if present
142 // see issue #5279
143 if (dateValue.length() > 1
144             && dateValue.startsWith("'")
145             && dateValue.endsWith("'")
146         ) {
147             dateValue = dateValue.substring (1, dateValue.length() - 1);
148         }
149         
150         SimpleDateFormat JavaDoc dateParser = null;
151         Iterator JavaDoc formatIter = dateFormats.iterator();
152         
153         while (formatIter.hasNext()) {
154             String JavaDoc format = (String JavaDoc) formatIter.next();
155             if (dateParser == null) {
156                 dateParser = new SimpleDateFormat JavaDoc(format, Locale.US);
157                 dateParser.setTimeZone(TimeZone.getTimeZone("GMT"));
158                 dateParser.set2DigitYearStart(startDate);
159             } else {
160                 dateParser.applyPattern(format);
161             }
162             try {
163                 return dateParser.parse(dateValue);
164             } catch (ParseException JavaDoc pe) {
165                 // ignore this exception, we will try the next format
166 }
167         }
168         
169         // we were unable to parse the date
170 throw new DateParseException("Unable to parse the date " + dateValue);
171     }
172
173     /**
174      * Formats the given date according to the RFC 1123 pattern.
175      *
176      * @param date The date to format.
177      * @return An RFC 1123 formatted date string.
178      *
179      * @see #PATTERN_RFC1123
180      */
181     public static String JavaDoc formatDate(Date JavaDoc date) {
182         return formatDate(date, PATTERN_RFC1123);
183     }
184     
185     /**
186      * Formats the given date according to the specified pattern. The pattern
187      * must conform to that used by the {@link SimpleDateFormat simple date
188      * format} class.
189      *
190      * @param date The date to format.
191      * @param pattern The pattern to use for formatting the date.
192      * @return A formatted date string.
193      *
194      * @throws IllegalArgumentException If the given date pattern is invalid.
195      *
196      * @see SimpleDateFormat
197      */
198     public static String JavaDoc formatDate(Date JavaDoc date, String JavaDoc pattern) {
199         if (date == null) throw new IllegalArgumentException JavaDoc("date is null");
200         if (pattern == null) throw new IllegalArgumentException JavaDoc("pattern is null");
201         
202         SimpleDateFormat JavaDoc formatter = new SimpleDateFormat JavaDoc(pattern, Locale.US);
203         formatter.setTimeZone(GMT);
204         return formatter.format(date);
205     }
206     
207     /** This class should not be instantiated. */
208     private DateUtil() { }
209     
210 }
211
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