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Java > Open Source Codes > org > roller > util > ISO8601DateParser


1 /*
2  * Copyright 1999,2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.roller.util;
17
18 import java.text.SimpleDateFormat JavaDoc;
19 import java.util.Date JavaDoc;
20 import java.util.TimeZone JavaDoc;
21
22 /**
23  * ISO 8601 date parsing utility. Designed for parsing the ISO subset used in
24  * Dublin Core, RSS 1.0, and Atom.
25  *
26  * @author <a HREF="mailto:burton@apache.org">Kevin A. Burton (burtonator)</a>
27  * @version $Id: ISO8601DateParser.java,v 1.2 2005/06/03 20:25:29 snoopdave Exp $
28  */
29 public class ISO8601DateParser {
30
31     // 2004-06-14T19:GMT20:30Z
32 // 2004-06-20T06:GMT22:01Z
33
34     private static SimpleDateFormat JavaDoc df
35         = new SimpleDateFormat JavaDoc( "yyyy-MM-dd'T'HH:mm:ssz" );
36
37     // http://www.cl.cam.ac.uk/~mgk25/iso-time.html
38 //
39 // http://www.intertwingly.net/wiki/pie/DateTime
40 //
41 // http://www.w3.org/TR/NOTE-datetime
42 //
43 // Different standards may need different levels of granularity in the date and
44 // time, so this profile defines six levels. Standards that reference this
45 // profile should specify one or more of these granularities. If a given
46 // standard allows more than one granularity, it should specify the meaning of
47 // the dates and times with reduced precision, for example, the result of
48 // comparing two dates with different precisions.
49
50     // The formats are as follows. Exactly the components shown here must be
51 // present, with exactly this punctuation. Note that the "T" appears literally
52 // in the string, to indicate the beginning of the time element, as specified in
53 // ISO 8601.
54
55     // Year:
56 // YYYY (eg 1997)
57 // Year and month:
58 // YYYY-MM (eg 1997-07)
59 // Complete date:
60 // YYYY-MM-DD (eg 1997-07-16)
61 // Complete date plus hours and minutes:
62 // YYYY-MM-DDThh:mmTZD (eg 1997-07-16T19:20+01:00)
63 // Complete date plus hours, minutes and seconds:
64 // YYYY-MM-DDThh:mm:ssTZD (eg 1997-07-16T19:20:30+01:00)
65 // Complete date plus hours, minutes, seconds and a decimal fraction of a
66 // second
67 // YYYY-MM-DDThh:mm:ss.sTZD (eg 1997-07-16T19:20:30.45+01:00)
68
69     // where:
70
71     // YYYY = four-digit year
72 // MM = two-digit month (01=January, etc.)
73 // DD = two-digit day of month (01 through 31)
74 // hh = two digits of hour (00 through 23) (am/pm NOT allowed)
75 // mm = two digits of minute (00 through 59)
76 // ss = two digits of second (00 through 59)
77 // s = one or more digits representing a decimal fraction of a second
78 // TZD = time zone designator (Z or +hh:mm or -hh:mm)
79 public static Date JavaDoc parse( String JavaDoc input ) throws java.text.ParseException JavaDoc {
80
81         //NOTE: SimpleDateFormat uses GMT[-+]hh:mm for the TZ which breaks
82 //things a bit. Before we go on we have to repair this.
83
84         //this is zero time so we need to add that TZ indicator for
85 if ( input.endsWith( "Z" ) ) {
86             input = input.substring( 0, input.length() - 1) + "GMT-00:00";
87         } else {
88             int inset = 6;
89         
90             String JavaDoc s0 = input.substring( 0, input.length() - inset );
91             String JavaDoc s1 = input.substring( input.length() - inset, input.length() );
92
93             input = s0 + "GMT" + s1;
94         }
95         
96         return df.parse( input );
97         
98     }
99
100     public static String JavaDoc toString( Date JavaDoc date ) {
101
102         TimeZone JavaDoc tz = TimeZone.getTimeZone( "UTC" );
103         
104         df.setTimeZone( tz );
105
106         String JavaDoc output = df.format( date );
107
108         int inset0 = 9;
109         int inset1 = 6;
110         
111         String JavaDoc s0 = output.substring( 0, output.length() - inset0 );
112         String JavaDoc s1 = output.substring( output.length() - inset1, output.length() );
113
114         String JavaDoc result = s0 + s1;
115
116         result = result.replaceAll( "UTC", "+00:00" );
117         
118         return result;
119         
120     }
121
122 }
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