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Java > Open Source Codes > com > opensymphony > module > sitemesh > mapper > LanguageDecoratorMapper


1 /*
2  * Title: LanguageDecoratorMapper
3  * Description:
4  *
5  * This software is published under the terms of the OpenSymphony Software
6  * License version 1.1, of which a copy has been included with this
7  * distribution in the LICENSE.txt file.
8  */
9
10 package com.opensymphony.module.sitemesh.mapper;
11
12 import com.opensymphony.module.sitemesh.Config;
13 import com.opensymphony.module.sitemesh.Decorator;
14 import com.opensymphony.module.sitemesh.DecoratorMapper;
15 import com.opensymphony.module.sitemesh.Page;
16
17 import javax.servlet.http.HttpServletRequest JavaDoc;
18 import java.io.File JavaDoc;
19 import java.util.HashMap JavaDoc;
20 import java.util.Iterator JavaDoc;
21 import java.util.Map JavaDoc;
22 import java.util.Properties JavaDoc;
23
24 /**
25  * The LanguageDecoratorMapper can determine the preferred language set in the
26  * browser requesting a page, and map to a suitable Decorator (using the
27  * "Accept-Language" HTTP header).
28  *
29  * <p>This can be useful for supplying different versions of the same content
30  * for different languages.</p>
31  *
32  * <p>When LanguageDecoratorMapper is in the chain, it will request the appropriate Decorator
33  * from its parent. It will then add an extention to the filename of the Decorator, and
34  * if that file exists it shall be used as the Decorator instead. For example, if the
35  * Decorator path is <code>/blah.jsp</code> and the detected preferred language is <code>en</code>,
36  * the path <code>/blah-en.jsp</code> shall be used.</p>
37  *
38  * <p>The language mappings are configured by passing properties with <code>match.</code> as a prefix.
39  * For example: 'match.en'=engl , 'match.nl'=dutch .</p>
40  *
41  * @author <a HREF="mailto:pathos@pandora.be">Mathias Bogaert</a>
42  *
43  * @see com.opensymphony.module.sitemesh.DecoratorMapper
44  */
45 public final class LanguageDecoratorMapper extends AbstractDecoratorMapper {
46     private Map JavaDoc map = null;
47
48     public void init(Config config, Properties JavaDoc properties, DecoratorMapper parent) throws InstantiationException JavaDoc {
49         super.init(config, properties, parent);
50         map = new HashMap JavaDoc();
51         initMap(properties);
52     }
53
54     public Decorator getDecorator(HttpServletRequest JavaDoc request, Page page) {
55         try {
56             Decorator result = null;
57             final Decorator d = super.getDecorator(request, page);
58             String JavaDoc path = modifyPath(d.getPage(), getExt(request.getHeader("Accept-Language")));
59
60             File JavaDoc decFile = new File JavaDoc(config.getServletContext().getRealPath(path));
61
62             if (decFile.isFile()) {
63                 result = new DefaultDecorator(d.getName(), path, null) {
64                     public String JavaDoc getInitParameter(String JavaDoc paramName) {
65                         return d.getInitParameter(paramName);
66                     }
67                 };
68             }
69             return result == null ? super.getDecorator(request, page) : result;
70         }
71         catch (NullPointerException JavaDoc e) {
72             return super.getDecorator(request, page);
73         }
74     }
75
76     /** Get extention for the language. */
77     private String JavaDoc getExt(String JavaDoc acceptLanguage) {
78         Iterator JavaDoc i = map.entrySet().iterator();
79         while (i.hasNext()) {
80             Map.Entry JavaDoc entry = (Map.Entry JavaDoc) i.next();
81
82            // Get the first language (preferred one) in the header, and
83 // only check the first two chars (the acceptLanguage could be en-gb, but
84 // we don't support this for now).
85 if (acceptLanguage.substring(0, 2).equals(entry.getKey())) {
86                 return (String JavaDoc) entry.getValue();
87             }
88
89             // When the user-agent has multiple accept-languages (separated by ;),
90 // these are ignored because the site creator may wish that if the
91 // preferred language is not supported, the page uses the default
92 // decorator (in the default language), and not in some other
93 // language given by the browser (most of them are specified by
94 // default at install).
95 }
96         return null;
97     }
98
99     /** Change /abc/def.jsp into /abc/def-XYZ.jsp */
100     private static String JavaDoc modifyPath(String JavaDoc path, String JavaDoc ext) {
101         int dot = path.indexOf('.');
102         if (dot > -1) {
103             return path.substring(0, dot) + '-' + ext + path.substring(dot);
104         }
105         else {
106             return path + '-' + ext;
107         }
108     }
109
110     /** Initialize language mappings. */
111     private void initMap(Properties JavaDoc props) {
112         Iterator JavaDoc i = props.entrySet().iterator();
113         while (i.hasNext()) {
114             Map.Entry JavaDoc entry = (Map.Entry JavaDoc) i.next();
115             String JavaDoc key = (String JavaDoc) entry.getKey();
116             if (key.startsWith("match.")) {
117                 String JavaDoc match = key.substring(6);
118                map.put(match, entry.getValue());
119             }
120         }
121     }
122 }
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