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.net.URL;
024 import java.util.Locale;
025 import java.util.Map;
026 import java.util.Properties;
027
028 import org.apache.commons.logging.Log;
029 import org.apache.commons.logging.LogFactory;
030
031 /**
032 * <p>Concrete implementation of
033 * {@link org.apache.commons.resources.Resources} that wraps a family
034 * (one per <code>Locale</code>) of properties files that share a base URL
035 * and have name suffixes reflecting the <code>Locale</code> for which
036 * the document's messages apply. Resources are looked up in a hierarchy
037 * of properties files in a manner identical to that performed by
038 * <code>java.util.ResourceBundle.getBundle().</code>.</p>
039 *
040 * <p>The base URL passed to our constructor must contain the base name
041 * of the properties file family.
042 * For example, if the configuration URL is passed as
043 * <code>http://localhost/foo/Bar</code>, the resources for the
044 * <code>en_US</code> Locale would be stored under URL
045 * <code>http://localhost/foo/Bar_en_US.properties</code>, and the default
046 * resources would be stored in
047 * <code>http://localhost/foo/Bar.properties</code>.</p>
048 */
049 public class PropertyResources extends CollectionResourcesBase {
050
051 /**
052 * <p>The <code>Log</code> instance for this class.</p>
053 */
054 private transient Log log = LogFactory.getLog(PropertyResources.class);
055
056 // ----------------------------------------------------------- Constructors
057
058 /**
059 * <p>Create a new
060 * {@link org.apache.commons.resources.Resources} instance with the specified
061 * logical name and base resource URL.</p>
062 *
063 * @param name Logical name of the new instance
064 * @param base Base URL of the family of properties files that contain
065 * the resource keys and values
066 */
067 public PropertyResources(String name, String base) {
068 super(name, base);
069 }
070
071
072 // ------------------------------------------------------ Protected Methods
073
074
075 /**
076 * <p>Return a <code>Map</code> containing the name-value mappings for
077 * the specified base URL and requested <code>Locale</code>, if there
078 * are any. If there are no defined mappings for the specified
079 * <code>Locale</code>, return an empty <code>Map</code> instead.</p>
080 *
081 * <p>Concrete subclasses must override this method to perform the
082 * appropriate lookup. A typical implementation will construct an
083 * absolute URL based on the specified base URL and <code>Locale</code>,
084 * retrieve the specified resource file (if any), and parse it into
085 * a <code>Map</code> structure.</p>
086 *
087 * <p>Caching of previously retrieved <code>Map</code>s (if any) should
088 * be performed by callers of this method. Therefore, this method should
089 * always attempt to retrieve the specified resource and load it
090 * appropriately.</p>
091 *
092 * @param baseUrl Base URL of the resource files for this
093 * {@link org.apache.commons.resources.Resources} instance
094 * @param locale <code>Locale</code> for which name-value mappings
095 * are requested
096 * @return A name-value Map for the specified URL and locale.
097 */
098 protected Map getLocaleMap(String baseUrl, Locale locale) {
099
100 if (getLog().isDebugEnabled()) {
101 getLog().debug("Loading locale '" + locale + "' resources from base '" +
102 baseUrl + "'");
103 }
104
105 Properties props = new Properties();
106 String name = baseUrl + getLocaleSuffix(locale) + ".properties";
107 InputStream stream = null;
108
109 try {
110
111 // Open an input stream to the URL for this locale (if any)
112 if (getLog().isTraceEnabled()) {
113 getLog().trace("Absolute URL is '" + name + "'");
114 }
115 URL url = new URL(name);
116 stream = url.openStream();
117
118 // Parse the input stream and populate the name-value mappings map
119 if (getLog().isTraceEnabled()) {
120 getLog().trace("Parsing input resource");
121 }
122 props.load(stream);
123
124 } catch (FileNotFoundException e) {
125
126 // Log and swallow this exception
127 if (getLog().isDebugEnabled()) {
128 getLog().debug("No resources for locale '" + locale +
129 "' from base '" + baseUrl + "'");
130 }
131 props.clear();
132
133 } catch (IOException e) {
134
135 getLog().warn("IOException loading locale '" + locale +
136 "' from base '" + baseUrl + "'", e);
137 props.clear();
138
139 } finally {
140
141 // Close the input stream that was opened earlier
142 if (stream != null) {
143 try {
144 stream.close();
145 } catch (IOException e) {
146 getLog().error("Error closing stream.", e);
147 }
148 stream = null;
149 }
150
151 }
152
153 // Return the populated (or empty) properties
154 return (props);
155
156 }
157
158
159 /**
160 * Accessor method for Log instance.
161 *
162 * The Log instance variable is transient and
163 * accessing it through this method ensures it
164 * is re-initialized when this instance is
165 * de-serialized.
166 *
167 * @return The Log instance.
168 */
169 private Log getLog() {
170 if (log == null) {
171 log = LogFactory.getLog(PropertyResources.class);
172 }
173 return log;
174 }
175
176 }