001 /*
002 * $Id: WebappXMLResources.java 348371 2005-11-23 04:56:51Z niallp $
003 * $Revision: 348371 $
004 * $Date: 2005-11-23 04:56:51 +0000 (Wed, 23 Nov 2005) $
005 *
006 * ====================================================================
007 *
008 * Copyright 2003-2005 The Apache Software Foundation
009 *
010 * Licensed under the Apache License, Version 2.0 (the "License");
011 * you may not use this file except in compliance with the License.
012 * You may obtain a copy of the License at
013 *
014 * http://www.apache.org/licenses/LICENSE-2.0
015 *
016 * Unless required by applicable law or agreed to in writing, software
017 * distributed under the License is distributed on an "AS IS" BASIS,
018 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
019 * See the License for the specific language governing permissions and
020 * limitations under the License.
021 *
022 */
023
024 package org.apache.commons.resources.impl;
025
026 import java.io.FileNotFoundException;
027 import java.io.IOException;
028 import java.io.InputStream;
029 import java.util.HashMap;
030 import java.util.Locale;
031 import java.util.Map;
032
033 import javax.servlet.ServletContext;
034
035 import org.apache.commons.digester.Digester;
036 import org.apache.commons.logging.Log;
037 import org.apache.commons.logging.LogFactory;
038 import org.xml.sax.SAXException;
039
040 /**
041 * <p>Concrete implementation of
042 * {@link org.apache.commons.resources.Resources} that wraps a family
043 * (one per <code>Locale</code> of XML documents that share a base
044 * context-relative path for servlet context resources, and have
045 * name suffixes reflecting the <code>Locale</code> for which
046 * the document's messages apply. Resources are looked up in a hierarchy
047 * of properties files in a manner identical to that performed by
048 * <code>java.util.ResourceBundle.getBundle().</code>.</p>
049 *
050 * <p>The base resource path passed to our constructor must contain the
051 * context-relative base name of the properties file family.
052 * For example, if the base path is passed as
053 * <code>http://localhost/foo/Bar</code>, the resources for the
054 * <code>en_US</code> Locale would be stored under URL
055 * <code>http://localhost/foo/Bar_en_US.xml</code>, and the default
056 * resources would be stored in
057 * <code>http://localhost/foo/Bar.xml</code>.</p>
058 */
059 public class WebappXMLResources extends CollectionResourcesBase {
060
061 /**
062 * <p>The <code>Log</code> instance for this class.</p>
063 */
064 private transient Log log = LogFactory.getLog(WebappXMLResources.class);
065
066 /**
067 * <p>Create a new {@link org.apache.commons.resources.Resources} instance with the specified
068 * logical name and base resource URL.</p>
069 *
070 * @param name Logical name of the new instance
071 * @param base Base URL of the family of properties files that contain
072 * the resource keys and values
073 * @param servletContext the <code>ServletContext</code> instance
074 * to use for resolving resource references
075 */
076 public WebappXMLResources(String name, String base,
077 ServletContext servletContext) {
078
079 super(name, base);
080 this.servletContext = servletContext;
081
082 }
083
084
085 // ----------------------------------------------------- Instance Variables
086
087 /**
088 * <p>The <code>ServletContext</code> instance for resolving
089 * our resources references.</p>
090 */
091 private ServletContext servletContext = null;
092
093
094 // ------------------------------------------------------ Protected Methods
095
096
097 /**
098 * <p>Return a <code>Map</code> containing the name-value mappings for
099 * the specified base URL and requested <code>Locale</code>, if there
100 * are any. If there are no defined mappings for the specified
101 * <code>Locale</code>, return an empty <code>Map</code> instead.</p>
102 *
103 * <p>Concrete subclasses must override this method to perform the
104 * appropriate lookup. A typical implementation will construct an
105 * absolute URL based on the specified base URL and <code>Locale</code>,
106 * retrieve the specified resource file (if any), and parse it into
107 * a <code>Map</code> structure.</p>
108 *
109 * <p>Caching of previously retrieved <code>Map</code>s (if any) should
110 * be performed by callers of this method. Therefore, this method should
111 * always attempt to retrieve the specified resource and load it
112 * appropriately.</p>
113 *
114 * @param baseUrl Base URL of the resource files for this {@link org.apache.commons.resources.Resources}
115 * instance
116 * @param locale <code>Locale</code> for which name-value mappings
117 * are requested
118 * @return A name-value Map for the specified URL and locale.
119 */
120 protected Map getLocaleMap(String baseUrl, Locale locale) {
121
122 if (getLog().isDebugEnabled()) {
123 getLog().debug("Loading locale '" + locale + "' resources from base '" +
124 baseUrl + "'");
125 }
126
127 Map map = new HashMap();
128 String name = baseUrl + getLocaleSuffix(locale) + ".xml";
129 InputStream stream = null;
130
131 try {
132
133 // Open an input stream to the URL for this locale (if any)
134 if (getLog().isTraceEnabled()) {
135 getLog().trace("Complete path is '" + name + "'");
136 }
137 stream = servletContext.getResourceAsStream(name);
138
139 // Create and configure a new Digester instance
140 if (stream != null) {
141
142 if (getLog().isTraceEnabled()) {
143 getLog().trace("Creating Digester instance");
144 }
145 Digester digester = new Digester();
146 digester.setNamespaceAware(false);
147 digester.setValidating(false);
148 digester.push(map);
149 digester.addCallMethod("resources/resource", "put", 2,
150 new String[] { "java.lang.Object",
151 "java.lang.Object" });
152 digester.addCallParam("resources/resource", 0, "id");
153 digester.addCallParam("resources/resource", 1);
154
155 // Parse the input stream and populate the name-value mappings
156 if (getLog().isTraceEnabled()) {
157 getLog().trace("Parsing input resource");
158 }
159 digester.parse(stream);
160
161 }
162
163 } catch (FileNotFoundException e) {
164
165 // Log and swallow this exception
166 if (getLog().isDebugEnabled()) {
167 getLog().debug("No resources for locale '" + locale +
168 "' from base '" + baseUrl + "'");
169 }
170 map.clear();
171
172 } catch (IOException e) {
173
174 // Log and swallow this exception
175 getLog().warn("IOException loading locale '" + locale +
176 "' from base '" + baseUrl + "'", e);
177 map.clear();
178
179 } catch (SAXException e) {
180
181 // Log and swallow this exception
182 getLog().warn("SAXException loading locale '" + locale +
183 "' from base '" + baseUrl + "'", e);
184 map.clear();
185
186 } finally {
187
188 // Close the input stream that was opened earlier
189 if (stream != null) {
190 try {
191 stream.close();
192 } catch (Exception e) {
193 // standard io
194 }
195 stream = null;
196 }
197
198 }
199
200 // Return the populated (or empty) map
201 return (map);
202
203
204 }
205
206 /**
207 * Accessor method for Log instance.
208 *
209 * The Log instance variable is transient and
210 * accessing it through this method ensures it
211 * is re-initialized when this instance is
212 * de-serialized.
213 *
214 * @return The Log instance.
215 */
216 private Log getLog() {
217 if (log == null) {
218 log = LogFactory.getLog(WebappXMLResources.class);
219 }
220 return log;
221 }
222
223 }