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30 package org.apache.commons.httpclient.util;
31
32 import java.text.ParseException;
33 import java.text.SimpleDateFormat;
34 import java.util.Arrays;
35 import java.util.Calendar;
36 import java.util.Collection;
37 import java.util.Date;
38 import java.util.Iterator;
39 import java.util.Locale;
40 import java.util.TimeZone;
41
42 import org.apache.commons.logging.Log;
43 import org.apache.commons.logging.LogFactory;
44
45 /***
46 * A utility class for parsing and formatting HTTP dates as used in cookies and
47 * other headers. This class handles dates as defined by RFC 2616 section
48 * 3.3.1 as well as some other common non-standard formats.
49 *
50 * @author Christopher Brown
51 * @author Michael Becke
52 */
53 public class DateUtil {
54
55 /*** Log object for this class. */
56 private static final Log LOG = LogFactory.getLog(DateUtil.class);
57
58 /***
59 * Date format pattern used to parse HTTP date headers in RFC 1123 format.
60 */
61 public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";
62
63 /***
64 * Date format pattern used to parse HTTP date headers in RFC 1036 format.
65 */
66 public static final String PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";
67
68 /***
69 * Date format pattern used to parse HTTP date headers in ANSI C
70 * <code>asctime()</code> format.
71 */
72 public static final String PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";
73
74 private static final Collection DEFAULT_PATTERNS = Arrays.asList(
75 new String[] { PATTERN_ASCTIME, PATTERN_RFC1036, PATTERN_RFC1123 } );
76
77 private static final Date DEFAULT_TWO_DIGIT_YEAR_START;
78
79 static {
80 Calendar calendar = Calendar.getInstance();
81 calendar.set(2000, Calendar.JANUARY, 1, 0, 0);
82 DEFAULT_TWO_DIGIT_YEAR_START = calendar.getTime();
83 }
84
85 private static final TimeZone GMT = TimeZone.getTimeZone("GMT");
86
87 /***
88 * Parses a date value. The formats used for parsing the date value are retrieved from
89 * the default http params.
90 *
91 * @param dateValue the date value to parse
92 *
93 * @return the parsed date
94 *
95 * @throws DateParseException if the value could not be parsed using any of the
96 * supported date formats
97 */
98 public static Date parseDate(String dateValue) throws DateParseException {
99 return parseDate(dateValue, null, null);
100 }
101
102 /***
103 * Parses the date value using the given date formats.
104 *
105 * @param dateValue the date value to parse
106 * @param dateFormats the date formats to use
107 *
108 * @return the parsed date
109 *
110 * @throws DateParseException if none of the dataFormats could parse the dateValue
111 */
112 public static Date parseDate(String dateValue, Collection dateFormats)
113 throws DateParseException {
114 return parseDate(dateValue, dateFormats, null);
115 }
116
117 /***
118 * Parses the date value using the given date formats.
119 *
120 * @param dateValue the date value to parse
121 * @param dateFormats the date formats to use
122 * @param startDate During parsing, two digit years will be placed in the range
123 * <code>startDate</code> to <code>startDate + 100 years</code>. This value may
124 * be <code>null</code>. When <code>null</code> is given as a parameter, year
125 * <code>2000</code> will be used.
126 *
127 * @return the parsed date
128 *
129 * @throws DateParseException if none of the dataFormats could parse the dateValue
130 */
131 public static Date parseDate(
132 String dateValue,
133 Collection dateFormats,
134 Date startDate
135 ) throws DateParseException {
136
137 if (dateValue == null) {
138 throw new IllegalArgumentException("dateValue is null");
139 }
140 if (dateFormats == null) {
141 dateFormats = DEFAULT_PATTERNS;
142 }
143 if (startDate == null) {
144 startDate = DEFAULT_TWO_DIGIT_YEAR_START;
145 }
146
147
148 if (dateValue.length() > 1
149 && dateValue.startsWith("'")
150 && dateValue.endsWith("'")
151 ) {
152 dateValue = dateValue.substring (1, dateValue.length() - 1);
153 }
154
155 SimpleDateFormat dateParser = null;
156 Iterator formatIter = dateFormats.iterator();
157
158 while (formatIter.hasNext()) {
159 String format = (String) formatIter.next();
160 if (dateParser == null) {
161 dateParser = new SimpleDateFormat(format, Locale.US);
162 dateParser.setTimeZone(TimeZone.getTimeZone("GMT"));
163 dateParser.set2DigitYearStart(startDate);
164 } else {
165 dateParser.applyPattern(format);
166 }
167 try {
168 return dateParser.parse(dateValue);
169 } catch (ParseException pe) {
170
171 }
172 }
173
174
175 throw new DateParseException("Unable to parse the date " + dateValue);
176 }
177
178 /***
179 * Formats the given date according to the RFC 1123 pattern.
180 *
181 * @param date The date to format.
182 * @return An RFC 1123 formatted date string.
183 *
184 * @see #PATTERN_RFC1123
185 */
186 public static String formatDate(Date date) {
187 return formatDate(date, PATTERN_RFC1123);
188 }
189
190 /***
191 * Formats the given date according to the specified pattern. The pattern
192 * must conform to that used by the {@link SimpleDateFormat simple date
193 * format} class.
194 *
195 * @param date The date to format.
196 * @param pattern The pattern to use for formatting the date.
197 * @return A formatted date string.
198 *
199 * @throws IllegalArgumentException If the given date pattern is invalid.
200 *
201 * @see SimpleDateFormat
202 */
203 public static String formatDate(Date date, String pattern) {
204 if (date == null) throw new IllegalArgumentException("date is null");
205 if (pattern == null) throw new IllegalArgumentException("pattern is null");
206
207 SimpleDateFormat formatter = new SimpleDateFormat(pattern, Locale.US);
208 formatter.setTimeZone(GMT);
209 return formatter.format(date);
210 }
211
212 /*** This class should not be instantiated. */
213 private DateUtil() { }
214
215 }