001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.resources.impl;
019
020 import java.io.FileNotFoundException;
021 import java.io.IOException;
022 import java.io.InputStream;
023 import java.util.HashMap;
024 import java.util.Locale;
025 import java.util.Map;
026
027 import javax.servlet.ServletContext;
028
029 import org.apache.commons.digester.Digester;
030 import org.apache.commons.logging.Log;
031 import org.apache.commons.logging.LogFactory;
032 import org.xml.sax.SAXException;
033
034 /**
035 * <p>Concrete implementation of
036 * {@link org.apache.commons.resources.Resources} that wraps a family
037 * (one per <code>Locale</code> of XML documents that share a base
038 * context-relative path for servlet context resources, and have
039 * name suffixes reflecting the <code>Locale</code> for which
040 * the document's messages apply. Resources are looked up in a hierarchy
041 * of properties files in a manner identical to that performed by
042 * <code>java.util.ResourceBundle.getBundle().</code>.</p>
043 *
044 * <p>The base resource path passed to our constructor must contain the
045 * context-relative base name of the properties file family.
046 * For example, if the base path is passed as
047 * <code>http://localhost/foo/Bar</code>, the resources for the
048 * <code>en_US</code> Locale would be stored under URL
049 * <code>http://localhost/foo/Bar_en_US.xml</code>, and the default
050 * resources would be stored in
051 * <code>http://localhost/foo/Bar.xml</code>.</p>
052 */
053 public class WebappXMLResources extends CollectionResourcesBase {
054
055 /**
056 * <p>The <code>Log</code> instance for this class.</p>
057 */
058 private transient Log log = LogFactory.getLog(WebappXMLResources.class);
059
060 /**
061 * <p>Create a new {@link org.apache.commons.resources.Resources} instance with the specified
062 * logical name and base resource URL.</p>
063 *
064 * @param name Logical name of the new instance
065 * @param base Base URL of the family of properties files that contain
066 * the resource keys and values
067 * @param servletContext the <code>ServletContext</code> instance
068 * to use for resolving resource references
069 */
070 public WebappXMLResources(String name, String base,
071 ServletContext servletContext) {
072
073 super(name, base);
074 this.servletContext = servletContext;
075
076 }
077
078
079 // ----------------------------------------------------- Instance Variables
080
081 /**
082 * <p>The <code>ServletContext</code> instance for resolving
083 * our resources references.</p>
084 */
085 private ServletContext servletContext = null;
086
087
088 // ------------------------------------------------------ Protected Methods
089
090
091 /**
092 * <p>Return a <code>Map</code> containing the name-value mappings for
093 * the specified base URL and requested <code>Locale</code>, if there
094 * are any. If there are no defined mappings for the specified
095 * <code>Locale</code>, return an empty <code>Map</code> instead.</p>
096 *
097 * <p>Concrete subclasses must override this method to perform the
098 * appropriate lookup. A typical implementation will construct an
099 * 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 }