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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  /**
32   * 
33   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
34   */
35  public class DateUtil {
36      /** A thread local is used to protect the DateFormat against concurrent access */
37      private static final ThreadLocal<DateFormat> RFC_1123_FORMAT = new ThreadLocal<DateFormat>() {
38          /**
39           * Initialize the formatter
40           */
41          protected DateFormat initialValue() {
42              DateFormat dateFormat = new SimpleDateFormat(RFC_1123_PATTERN, Locale.US);
43              TimeZone gmtZone = TimeZone.getTimeZone("GMT");
44              dateFormat.setTimeZone(gmtZone);
45  
46              return dateFormat;
47          }
48      };
49  
50      /** The format of an HTTP date */
51      private static final String RFC_1123_PATTERN = "EEE, dd MMM yyyy HH:mm:ss zzz";
52  
53      /** Pattern to find digits only. */
54      private static final Pattern DIGIT_PATTERN = Pattern.compile("^\\d+$");
55  
56      /**
57       * Returns the current date as String
58       *
59       * @return Current Date as String, in the format <i>EEE, dd MMM yyyy HH:mm:ss zzz</i>
60       */
61      public static String getCurrentAsString() {
62          return RFC_1123_FORMAT.get().format(new Date());
63      }
64  
65      /**
66       * Translate a given date <code>String</code> in the <em>RFC 1123</em>
67       * format to a <code>long</code> representing the number of milliseconds
68       * since epoch.
69       * 
70       * @param dateString a date <code>String</code> in the <em>RFC 1123</em>
71       *            format.
72       * @return the parsed <code>Date</code> in milliseconds.
73       */
74      private static long parseDateStringToMilliseconds(final String dateString) {
75  
76          try {
77              return RFC_1123_FORMAT.get().parse(dateString).getTime();
78          } catch (final ParseException e) {
79              return 0;
80          }
81      }
82  
83      /**
84       * Parse a given date <code>String</code> to a <code>long</code>
85       * representation of the time. Where the provided value is all digits the
86       * value is returned as a <code>long</code>, otherwise attempt is made to
87       * parse the <code>String</code> as a <em>RFC 1123</em> date.
88       * 
89       * @param dateValue the value to parse.
90       * @return the <code>long</code> value following parse, or zero where not
91       *         successful.
92       */
93      public static long parseToMilliseconds(final String dateValue) {
94  
95          long ms = 0;
96  
97          if (DIGIT_PATTERN.matcher(dateValue).matches()) {
98              ms = Long.parseLong(dateValue);
99          } else {
100             ms = parseDateStringToMilliseconds(dateValue);
101         }
102 
103         return ms;
104     }
105 
106     /**
107      * Converts a millisecond representation of a date to a
108      * <code>RFC 1123</code> formatted <code>String</code>.
109      * 
110      * @param dateValue the <code>Date</code> represented as milliseconds.
111      * @return a <code>String</code> representation of the date.
112      */
113     public static String parseToRFC1123(final long dateValue) {
114         final Calendar calendar = Calendar.getInstance();
115         calendar.setTimeInMillis(dateValue);
116 
117         return RFC_1123_FORMAT.get().format(calendar.getTime());
118     }
119 
120     /**
121      * Convert a given <code>Date</code> object to a <code>RFC 1123</code>
122      * formatted <code>String</code>.
123      * 
124      * @param date the <code>Date</code> object to convert
125      * @return a <code>String</code> representation of the date.
126      */
127     public static String getDateAsString(Date date) {
128         return RFC_1123_FORMAT.get().format(date);
129     }
130 }