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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  package org.apache.mina.http;
21  
22  import java.text.DateFormat;
23  import java.text.ParseException;
24  import java.text.SimpleDateFormat;
25  import java.util.Calendar;
26  import java.util.Date;
27  import java.util.Locale;
28  import java.util.TimeZone;
29  import java.util.regex.Pattern;
30  
31  public class DateUtil {
32  
33      private final static Locale LOCALE = Locale.US;
34      private final static TimeZone GMT_ZONE;
35      private final static String RFC_1123_PATTERN = "EEE, dd MMM yyyy HH:mm:ss zzz";
36      private final static DateFormat RFC_1123_FORMAT;
37  
38      /** Pattern to find digits only. */
39      private final static Pattern DIGIT_PATTERN = Pattern.compile("^\\d+$");
40  
41      static {
42          RFC_1123_FORMAT = new SimpleDateFormat(DateUtil.RFC_1123_PATTERN, DateUtil.LOCALE);
43          GMT_ZONE = TimeZone.getTimeZone("GMT");
44          DateUtil.RFC_1123_FORMAT.setTimeZone(DateUtil.GMT_ZONE);
45      }
46  
47      public static String getCurrentAsString() {
48          return DateUtil.RFC_1123_FORMAT.format(new Date()); //NOPMD
49      }
50  
51      /**
52       * Translate a given date <code>String</code> in the <em>RFC 1123</em>
53       * format to a <code>long</code> representing the number of milliseconds
54       * since epoch.
55       * 
56       * @param dateString a date <code>String</code> in the <em>RFC 1123</em>
57       *            format.
58       * @return the parsed <code>Date</code> in milliseconds.
59       */
60      private static long parseDateStringToMilliseconds(final String dateString) {
61  
62          try {
63              return DateUtil.RFC_1123_FORMAT.parse(dateString).getTime(); //NOPMD
64          } catch (final ParseException e) {
65              return 0;
66          }
67      }
68  
69      /**
70       * Parse a given date <code>String</code> to a <code>long</code>
71       * representation of the time. Where the provided value is all digits the
72       * value is returned as a <code>long</code>, otherwise attempt is made to
73       * parse the <code>String</code> as a <em>RFC 1123</em> date.
74       * 
75       * @param dateValue the value to parse.
76       * @return the <code>long</code> value following parse, or zero where not
77       *         successful.
78       */
79      public static long parseToMilliseconds(final String dateValue) {
80  
81          long ms = 0;
82  
83          if (DateUtil.DIGIT_PATTERN.matcher(dateValue).matches()) {
84              ms = Long.parseLong(dateValue);
85          } else {
86              ms = parseDateStringToMilliseconds(dateValue);
87          }
88  
89          return ms;
90      }
91  
92      /**
93       * Converts a millisecond representation of a date to a
94       * <code>RFC 1123</code> formatted <code>String</code>.
95       * 
96       * @param dateValue the <code>Date</code> represented as milliseconds.
97       * @return a <code>String</code> representation of the date.
98       */
99      public static String parseToRFC1123(final long dateValue) {
100 
101         final Calendar calendar = Calendar.getInstance();
102         calendar.setTimeInMillis(dateValue);
103 
104         return DateUtil.RFC_1123_FORMAT.format(calendar.getTime()); //NOPMD
105     }
106 
107     /**
108      * Convert a given <code>Date</code> object to a <code>RFC 1123</code>
109      * formatted <code>String</code>.
110      * 
111      * @param date the <code>Date</code> object to convert
112      * @return a <code>String</code> representation of the date.
113      */
114     public static String getDateAsString(Date date) {
115         return RFC_1123_FORMAT.format(date); //NOPMD
116     }
117 
118 }