1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.resources.impl;
19
20 import java.io.FileNotFoundException;
21 import java.io.IOException;
22 import java.io.InputStream;
23 import java.util.HashMap;
24 import java.util.Locale;
25 import java.util.Map;
26
27 import javax.servlet.ServletContext;
28
29 import org.apache.commons.digester.Digester;
30 import org.apache.commons.logging.Log;
31 import org.apache.commons.logging.LogFactory;
32 import org.xml.sax.SAXException;
33
34 /**
35 * <p>Concrete implementation of
36 * {@link org.apache.commons.resources.Resources} that wraps a family
37 * (one per <code>Locale</code> of XML documents that share a base
38 * context-relative path for servlet context resources, and have
39 * name suffixes reflecting the <code>Locale</code> for which
40 * the document's messages apply. Resources are looked up in a hierarchy
41 * of properties files in a manner identical to that performed by
42 * <code>java.util.ResourceBundle.getBundle().</code>.</p>
43 *
44 * <p>The base resource path passed to our constructor must contain the
45 * context-relative base name of the properties file family.
46 * For example, if the base path is passed as
47 * <code>http://localhost/foo/Bar</code>, the resources for the
48 * <code>en_US</code> Locale would be stored under URL
49 * <code>http://localhost/foo/Bar_en_US.xml</code>, and the default
50 * resources would be stored in
51 * <code>http://localhost/foo/Bar.xml</code>.</p>
52 */
53 public class WebappXMLResources extends CollectionResourcesBase {
54
55 /**
56 * <p>The <code>Log</code> instance for this class.</p>
57 */
58 private transient Log log = LogFactory.getLog(WebappXMLResources.class);
59
60 /**
61 * <p>Create a new {@link org.apache.commons.resources.Resources} instance with the specified
62 * logical name and base resource URL.</p>
63 *
64 * @param name Logical name of the new instance
65 * @param base Base URL of the family of properties files that contain
66 * the resource keys and values
67 * @param servletContext the <code>ServletContext</code> instance
68 * to use for resolving resource references
69 */
70 public WebappXMLResources(String name, String base,
71 ServletContext servletContext) {
72
73 super(name, base);
74 this.servletContext = servletContext;
75
76 }
77
78
79 // ----------------------------------------------------- Instance Variables
80
81 /**
82 * <p>The <code>ServletContext</code> instance for resolving
83 * our resources references.</p>
84 */
85 private ServletContext servletContext = null;
86
87
88 // ------------------------------------------------------ Protected Methods
89
90
91 /**
92 * <p>Return a <code>Map</code> containing the name-value mappings for
93 * the specified base URL and requested <code>Locale</code>, if there
94 * are any. If there are no defined mappings for the specified
95 * <code>Locale</code>, return an empty <code>Map</code> instead.</p>
96 *
97 * <p>Concrete subclasses must override this method to perform the
98 * appropriate lookup. A typical implementation will construct an
99 * absolute URL based on the specified base URL and <code>Locale</code>,
100 * retrieve the specified resource file (if any), and parse it into
101 * a <code>Map</code> structure.</p>
102 *
103 * <p>Caching of previously retrieved <code>Map</code>s (if any) should
104 * be performed by callers of this method. Therefore, this method should
105 * always attempt to retrieve the specified resource and load it
106 * appropriately.</p>
107 *
108 * @param baseUrl Base URL of the resource files for this {@link org.apache.commons.resources.Resources}
109 * instance
110 * @param locale <code>Locale</code> for which name-value mappings
111 * are requested
112 * @return A name-value Map for the specified URL and locale.
113 */
114 protected Map getLocaleMap(String baseUrl, Locale locale) {
115
116 if (getLog().isDebugEnabled()) {
117 getLog().debug("Loading locale '" + locale + "' resources from base '" +
118 baseUrl + "'");
119 }
120
121 Map map = new HashMap();
122 String name = baseUrl + getLocaleSuffix(locale) + ".xml";
123 InputStream stream = null;
124
125 try {
126
127 // Open an input stream to the URL for this locale (if any)
128 if (getLog().isTraceEnabled()) {
129 getLog().trace("Complete path is '" + name + "'");
130 }
131 stream = servletContext.getResourceAsStream(name);
132
133 // Create and configure a new Digester instance
134 if (stream != null) {
135
136 if (getLog().isTraceEnabled()) {
137 getLog().trace("Creating Digester instance");
138 }
139 Digester digester = new Digester();
140 digester.setNamespaceAware(false);
141 digester.setValidating(false);
142 digester.push(map);
143 digester.addCallMethod("resources/resource", "put", 2,
144 new String[] { "java.lang.Object",
145 "java.lang.Object" });
146 digester.addCallParam("resources/resource", 0, "id");
147 digester.addCallParam("resources/resource", 1);
148
149 // Parse the input stream and populate the name-value mappings
150 if (getLog().isTraceEnabled()) {
151 getLog().trace("Parsing input resource");
152 }
153 digester.parse(stream);
154
155 }
156
157 } catch (FileNotFoundException e) {
158
159 // Log and swallow this exception
160 if (getLog().isDebugEnabled()) {
161 getLog().debug("No resources for locale '" + locale +
162 "' from base '" + baseUrl + "'");
163 }
164 map.clear();
165
166 } catch (IOException e) {
167
168 // Log and swallow this exception
169 getLog().warn("IOException loading locale '" + locale +
170 "' from base '" + baseUrl + "'", e);
171 map.clear();
172
173 } catch (SAXException e) {
174
175 // Log and swallow this exception
176 getLog().warn("SAXException loading locale '" + locale +
177 "' from base '" + baseUrl + "'", e);
178 map.clear();
179
180 } finally {
181
182 // Close the input stream that was opened earlier
183 if (stream != null) {
184 try {
185 stream.close();
186 } catch (Exception e) {
187 // standard io
188 }
189 stream = null;
190 }
191
192 }
193
194 // Return the populated (or empty) map
195 return (map);
196
197
198 }
199
200 /**
201 * Accessor method for Log instance.
202 *
203 * The Log instance variable is transient and
204 * accessing it through this method ensures it
205 * is re-initialized when this instance is
206 * de-serialized.
207 *
208 * @return The Log instance.
209 */
210 private Log getLog() {
211 if (log == null) {
212 log = LogFactory.getLog(WebappXMLResources.class);
213 }
214 return log;
215 }
216
217 }