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/*
* $Id: PropertyMessageResources.java 54929 2004-10-16 16:38:42Z germuska $
*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.struts.util;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Locale;
import java.util.Properties;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Concrete subclass of MessageResources that reads message keys
* and corresponding strings from named property resources in the same manner
* that java.util.PropertyResourceBundle does. The
* base property defines the base property resource name, and
* must be specified.
*
* IMPLEMENTATION NOTE - This class trades memory for
* speed by caching all messages located via generalizing the Locale under
* the original locale as well.
* This results in specific messages being stored in the message cache
* more than once, but improves response time on subsequent requests for
* the same locale + key combination.
*
* @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
*/
public class PropertyMessageResources extends MessageResources {
// ----------------------------------------------------------- Constructors
/**
* Construct a new PropertyMessageResources according to the
* specified parameters.
*
* @param factory The MessageResourcesFactory that created us
* @param config The configuration parameter for this MessageResources
*/
public PropertyMessageResources(MessageResourcesFactory factory,
String config) {
super(factory, config);
log.trace("Initializing, config='" + config + "'");
}
/**
* Construct a new PropertyMessageResources according to the
* specified parameters.
*
* @param factory The MessageResourcesFactory that created us
* @param config The configuration parameter for this MessageResources
* @param returnNull The returnNull property we should initialize with
*/
public PropertyMessageResources(MessageResourcesFactory factory,
String config, boolean returnNull) {
super(factory, config, returnNull);
log.trace("Initializing, config='" + config +
"', returnNull=" + returnNull);
}
// ------------------------------------------------------------- Properties
/**
* The set of locale keys for which we have already loaded messages, keyed
* by the value calculated in localeKey().
*/
protected HashMap locales = new HashMap();
/**
* The Log instance for this class.
*/
protected static final Log log =
LogFactory.getLog(PropertyMessageResources.class);
/**
* The cache of messages we have accumulated over time, keyed by the
* value calculated in messageKey().
*/
protected HashMap messages = new HashMap();
// --------------------------------------------------------- Public Methods
/**
* Returns a text message for the specified key, for the default Locale.
* A null string result will be returned by this method if no relevant
* message resource is found for this key or Locale, if the
* returnNull property is set. Otherwise, an appropriate
* error message will be returned.
*
* This method must be implemented by a concrete subclass.
*
* @param locale The requested message Locale, or null
* for the system default Locale
* @param key The message key to look up
* @return text message for the specified key and locale
*/
public String getMessage(Locale locale, String key) {
if (log.isDebugEnabled()) {
log.debug("getMessage(" + locale + "," + key + ")");
}
// Initialize variables we will require
String localeKey = localeKey(locale);
String originalKey = messageKey(localeKey, key);
String messageKey = null;
String message = null;
int underscore = 0;
boolean addIt = false; // Add if not found under the original key
// Loop from specific to general Locales looking for this message
while (true) {
// Load this Locale's messages if we have not done so yet
loadLocale(localeKey);
// Check if we have this key for the current locale key
messageKey = messageKey(localeKey, key);
synchronized (messages) {
message = (String) messages.get(messageKey);
if (message != null) {
if (addIt) {
messages.put(originalKey, message);
}
return (message);
}
}
// Strip trailing modifiers to try a more general locale key
addIt = true;
underscore = localeKey.lastIndexOf("_");
if (underscore < 0) {
break;
}
localeKey = localeKey.substring(0, underscore);
}
// Try the default locale if the current locale is different
if (!defaultLocale.equals(locale)) {
localeKey = localeKey(defaultLocale);
messageKey = messageKey(localeKey, key);
loadLocale(localeKey);
synchronized (messages) {
message = (String) messages.get(messageKey);
if (message != null) {
messages.put(originalKey, message);
return (message);
}
}
}
// As a last resort, try the default Locale
localeKey = "";
messageKey = messageKey(localeKey, key);
loadLocale(localeKey);
synchronized (messages) {
message = (String) messages.get(messageKey);
if (message != null) {
messages.put(originalKey, message);
return (message);
}
}
// Return an appropriate error indication
if (returnNull) {
return (null);
} else {
return ("???" + messageKey(locale, key) + "???");
}
}
// ------------------------------------------------------ Protected Methods
/**
* Load the messages associated with the specified Locale key. For this
* implementation, the config property should contain a fully
* qualified package and resource name, separated by periods, of a series
* of property resources to be loaded from the class loader that created
* this PropertyMessageResources instance. This is exactly the same name
* format you would use when utilizing the
* java.util.PropertyResourceBundle class.
*
* @param localeKey Locale key for the messages to be retrieved
*/
protected synchronized void loadLocale(String localeKey) {
if (log.isTraceEnabled()) {
log.trace("loadLocale(" + localeKey + ")");
}
// Have we already attempted to load messages for this locale?
if (locales.get(localeKey) != null) {
return;
}
locales.put(localeKey, localeKey);
// Set up to load the property resource for this locale key, if we can
String name = config.replace('.', '/');
if (localeKey.length() > 0) {
name += "_" + localeKey;
}
name += ".properties";
InputStream is = null;
Properties props = new Properties();
// Load the specified property resource
if (log.isTraceEnabled()) {
log.trace(" Loading resource '" + name + "'");
}
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
if (classLoader == null) {
classLoader = this.getClass().getClassLoader();
}
is = classLoader.getResourceAsStream(name);
if (is != null) {
try {
props.load(is);
} catch (IOException e) {
log.error("loadLocale()", e);
} finally {
try {
is.close();
} catch (IOException e) {
log.error("loadLocale()", e);
}
}
}
if (log.isTraceEnabled()) {
log.trace(" Loading resource completed");
}
// Copy the corresponding values into our cache
if (props.size() < 1) {
return;
}
synchronized (messages) {
Iterator names = props.keySet().iterator();
while (names.hasNext()) {
String key = (String) names.next();
if (log.isTraceEnabled()) {
log.trace(" Saving message key '" + messageKey(localeKey, key));
}
messages.put(messageKey(localeKey, key), props.getProperty(key));
}
}
}
}