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


1 /*
2  * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/util/DateParser.java,v 1.3.2.2 2004/02/22 18:21:16 olegk Exp $
3  * $Revision: 1.3.2.2 $
4  * $Date: 2004/02/22 18:21:16 $
5  *
6  * ====================================================================
7  *
8  * Copyright 1999-2004 The Apache Software Foundation
9  *
10  * Licensed under the Apache License, Version 2.0 (the "License");
11  * you may not use this file except in compliance with the License.
12  * You may obtain a copy of the License at
13  *
14  * http://www.apache.org/licenses/LICENSE-2.0
15  *
16  * Unless required by applicable law or agreed to in writing, software
17  * distributed under the License is distributed on an "AS IS" BASIS,
18  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19  * See the License for the specific language governing permissions and
20  * limitations under the License.
21  * ====================================================================
22  *
23  * This software consists of voluntary contributions made by many
24  * individuals on behalf of the Apache Software Foundation. For more
25  * information on the Apache Software Foundation, please see
26  * <http://www.apache.org/>.
27  *
28  * [Additional notices, if required by prior licensing conditions]
29  *
30  */
31
32 package org.apache.commons.httpclient.util;
33
34 import java.text.ParseException JavaDoc;
35 import java.text.SimpleDateFormat JavaDoc;
36 import java.util.Date JavaDoc;
37 import java.util.Locale JavaDoc;
38 import java.util.TimeZone JavaDoc;
39
40 /**
41  * A utility class for parsing HTTP dates as used in cookies and other headers.
42  * This class handles dates as defined by RFC 2616 section 3.3.1 as well as
43  * some other common non-standard formats.
44  *
45  * @author Christopher Brown
46  * @author Michael Becke
47  */
48 public class DateParser {
49
50     /**
51      * Date format pattern used to parse HTTP date headers in RFC 1123 format.
52      */
53     public static final String JavaDoc PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";
54
55     /**
56      * Date format pattern used to parse HTTP date headers in RFC 1036 format.
57      */
58     public static final String JavaDoc PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";
59
60     /**
61      * Date format pattern used to parse HTTP date headers in ANSI C
62      * <code>asctime()</code> format.
63      */
64     public static final String JavaDoc PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";
65
66     /** The patterns used for parsing dates */
67     private static final String JavaDoc[] DATE_PATTERNS = {
68         PATTERN_RFC1123,
69         PATTERN_RFC1036,
70         PATTERN_ASCTIME,
71         "EEE, dd-MMM-yyyy HH:mm:ss z",
72         "EEE, dd-MMM-yyyy HH-mm-ss z",
73         "EEE, dd MMM yy HH:mm:ss z",
74         "EEE dd-MMM-yyyy HH:mm:ss z",
75         "EEE dd MMM yyyy HH:mm:ss z",
76         "EEE dd-MMM-yyyy HH-mm-ss z",
77         "EEE dd-MMM-yy HH:mm:ss z",
78         "EEE dd MMM yy HH:mm:ss z",
79         "EEE,dd-MMM-yy HH:mm:ss z",
80         "EEE,dd-MMM-yyyy HH:mm:ss z",
81         "EEE, dd-MM-yyyy HH:mm:ss z",
82     };
83
84     /**
85      * Parses a date value.
86      *
87      * @param dateValue the date value to parse
88      *
89      * @return the parsed date
90      *
91      * @throws DateParseException if the value could not be parsed using any of the
92      * supported date formats
93      */
94     public static Date JavaDoc parseDate(String JavaDoc dateValue) throws DateParseException {
95         return parseDate(dateValue, DATE_PATTERNS);
96     }
97     
98     /**
99      * Parses the date value using the array of date formats.
100      *
101      * @param dateValue the date value to parse
102      * @param dateFormats the date formats to use
103      *
104      * @return the parsed date
105      *
106      * @throws DateParseException if none of the dataFormats could parse the dateValue
107      */
108     private static Date JavaDoc parseDate(
109         String JavaDoc dateValue,
110         String JavaDoc[] dateFormats
111     ) throws DateParseException {
112         
113         if (dateValue == null) {
114             throw new IllegalArgumentException JavaDoc("dateValue is null");
115         }
116         
117         SimpleDateFormat JavaDoc dateParser = null;
118         
119         for (int i = 0; i < dateFormats.length; i++) {
120             if (dateParser == null) {
121                 dateParser = new SimpleDateFormat JavaDoc(dateFormats[i], Locale.US);
122                 dateParser.setTimeZone(TimeZone.getTimeZone("GMT"));
123             } else {
124                 dateParser.applyPattern(dateFormats[i]);
125             }
126             try {
127                 return dateParser.parse(dateValue);
128             } catch (ParseException JavaDoc pe) {
129                 // ignore this exception, we will try the next format
130 }
131         }
132         
133         // we were unable to parse the date
134 throw new DateParseException("Unable to parse the date " + dateValue);
135     }
136
137     /** This class should not be instantiated. */
138     private DateParser() { }
139     
140 }
141
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