// Copyright 2006, 2007 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.tapestry.internal.services;
import static org.apache.tapestry.ioc.internal.util.CollectionFactory.newCaseInsensitiveMap;
import static org.apache.tapestry.ioc.internal.util.CollectionFactory.newList;
import static org.apache.tapestry.ioc.internal.util.CollectionFactory.newThreadSafeMap;
import java.io.BufferedInputStream;
import java.io.InputStream;
import java.net.URL;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;
import org.apache.tapestry.internal.TapestryUtils;
import org.apache.tapestry.internal.event.InvalidationEventHubImpl;
import org.apache.tapestry.internal.util.MultiKey;
import org.apache.tapestry.internal.util.URLChangeTracker;
import org.apache.tapestry.ioc.Messages;
import org.apache.tapestry.ioc.Resource;
import org.apache.tapestry.ioc.internal.util.LocalizedNameGenerator;
/**
* A utility class that encapsulates all the logic for reading properties files and assembling
* {@link Messages} from them, in accordance with extension rules and locale. This represents code
* that was refactored out of {@link ComponentMessagesSourceImpl}. This class can be used as a base
* class, though the existing code base uses it as a utility. Composition trumps inheritance!
*/
public class MessagesSourceImpl extends InvalidationEventHubImpl implements MessagesSource
{
private final URLChangeTracker _tracker;
/** Keyed on bundle id and locale. */
private final Map<MultiKey, Messages> _messagesByBundleIdAndLocale = newThreadSafeMap();
/**
* Keyed on bundle id and locale, the coooked properties include properties inherited from less
* locale-specific properties files, or inherited from parent bundles.
*/
private final Map<MultiKey, Map<String, String>> _cookedProperties = newThreadSafeMap();
/**
* Raw properties represent just the properties read from a specific properties file, in
* isolation.
*/
private final Map<Resource, Map<String, String>> _rawProperties = newThreadSafeMap();
private final Map<String, String> _emptyMap = Collections.emptyMap();
public MessagesSourceImpl(URLChangeTracker tracker)
{
_tracker = tracker;
}
public void checkForUpdates()
{
if (_tracker.containsChanges())
{
_messagesByBundleIdAndLocale.clear();
_cookedProperties.clear();
_rawProperties.clear();
_tracker.clear();
fireInvalidationEvent();
}
}
public Messages getMessages(MessagesBundle bundle, Locale locale)
{
MultiKey key = new MultiKey(bundle.getId(), locale);
Messages result = _messagesByBundleIdAndLocale.get(key);
if (result == null)
{
result = buildMessages(bundle, locale);
_messagesByBundleIdAndLocale.put(key, result);
}
return result;
}
private Messages buildMessages(MessagesBundle bundle, Locale locale)
{
Map<String, String> properties = findBundleProperties(bundle, locale);
return new MapMessages(properties);
}
/**
* Assembles a set of properties appropriate for the bundle in question, and the desired locale.
* The properties reflect the properties of the bundles' parent (if any) for the locale,
* overalyed with any properties defined for this bundle and its locale.
*/
private Map<String, String> findBundleProperties(MessagesBundle bundle, Locale locale)
{
if (bundle == null)
return _emptyMap;
MultiKey key = new MultiKey(bundle.getId(), locale);
Map<String, String> existing = _cookedProperties.get(key);
if (existing != null)
return existing;
// What would be cool is if we could maintain a cache of bundle id + locale -->
// Resource. That would optimize quite a bit of this; may need to use an alternative to
// LocalizedNameGenerator.
Resource propertiesResource = bundle.getBaseResource().withExtension("properties");
List<Resource> localizations = newList();
for (String localizedFile : new LocalizedNameGenerator(propertiesResource.getFile(), locale))
{
Resource localized = propertiesResource.forFile(localizedFile);
localizations.add(localized);
}
// We need them in least-specific to most-specific order, the opposite
// of how the LocalizedNameGenerator provides them.
Collections.reverse(localizations);
// Localizations are now in least-specific to most-specific order.
Map<String, String> previous = findBundleProperties(bundle.getParent(), locale);
for (Resource localization : localizations)
{
Map<String, String> rawProperties = getRawProperties(localization);
Map<String, String> properties = extend(previous, rawProperties);
// Woould be nice to write into the _cookedProperties cache here,
// but we can't because we don't know the locale part of the MultiKey.
previous = properties;
}
_cookedProperties.put(key, previous);
return previous;
}
/**
* Returns a new map consisting of all the properties in previous overlayed with all the
* properties in rawProperties. If rawProperties is empty, returns just the base map.
*/
private Map<String, String> extend(Map<String, String> base, Map<String, String> rawProperties)
{
if (rawProperties.isEmpty())
return base;
// Make a copy of the base Map
Map<String, String> result = newCaseInsensitiveMap(base);
// Add or overwrite properties to the copy
result.putAll(rawProperties);
return result;
}
private Map<String, String> getRawProperties(Resource localization)
{
Map<String, String> result = _rawProperties.get(localization);
if (result == null)
{
result = readProperties(localization);
_rawProperties.put(localization, result);
}
return result;
}
/**
* Creates and returns a new map that contains properties read from the properties file.
*/
private Map<String, String> readProperties(Resource resource)
{
URL url = resource.toURL();
if (url == null)
return _emptyMap;
_tracker.add(url);
Map<String, String> result = newCaseInsensitiveMap();
Properties p = new Properties();
InputStream is = null;
try
{
is = new BufferedInputStream(url.openStream());
p.load(is);
is.close();
is = null;
}
catch (Exception ex)
{
throw new RuntimeException(ServicesMessages.failureReadingMessages(url, ex), ex);
}
finally
{
TapestryUtils.close(is);
}
for (Map.Entry e : p.entrySet())
{
String key = e.getKey().toString();
String value = p.getProperty(key);
result.put(key, value);
}
return result;
}
}