// Copyright 2010 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.tapestry5.internal.services;
import java.util.Locale;
import java.util.Map;
import org.apache.tapestry5.ioc.AnnotationProvider;
import org.apache.tapestry5.ioc.Messages;
import org.apache.tapestry5.ioc.ObjectCreator;
import org.apache.tapestry5.ioc.ObjectLocator;
import org.apache.tapestry5.ioc.ObjectProvider;
import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
import org.apache.tapestry5.ioc.services.ClassFactory;
import org.apache.tapestry5.ioc.services.ThreadLocale;
import org.apache.tapestry5.services.InvalidationListener;
import org.apache.tapestry5.services.messages.ComponentMessagesSource;
/**
* Allows for injection of the global application message catalog into services. The injected value
* is, in fact, a proxy. Each method access of the proxy will determine the current thread's locale, and delegate
* to the actual global message catalog for that particular locale. There's caching to keep it reasonably
* efficient.
*
* @since 5.2.0
* @see ComponentMessagesSource#getApplicationCatalog(Locale)
*/
public class ApplicationMessageCatalogObjectProvider implements ObjectProvider, InvalidationListener
{
private final ObjectLocator objectLocator;
private ComponentMessagesSource messagesSource;
private ThreadLocale threadLocale;
private final Map<Locale, Messages> localeToMessages = CollectionFactory.newMap();
private Messages proxy;
private class ApplicationMessagesObjectCreator implements ObjectCreator
{
public Object createObject()
{
Locale locale = threadLocale.getLocale();
Messages messages = localeToMessages.get(locale);
if (messages == null)
{
messages = messagesSource.getApplicationCatalog(locale);
localeToMessages.put(locale, messages);
}
return messages;
}
};
public ApplicationMessageCatalogObjectProvider(ObjectLocator locator)
{
this.objectLocator = locator;
}
/**
* Because this is an ObjectProvider and is part of the MasterObjectProvider pipeline, it has to
* be careful to not require further dependencies at construction time. This means we have to "drop out"
* of normal IoC dependency injection and adopt a lookup strategy based on the ObjectLocator. Further,
* we have to be careful about multi-threading issues.
*/
private synchronized Messages getProxy()
{
if (proxy == null)
{
this.messagesSource = objectLocator.getService(ComponentMessagesSource.class);
this.threadLocale = objectLocator.getService(ThreadLocale.class);
ClassFactory classFactory = objectLocator.getService("ClassFactory", ClassFactory.class);
proxy = classFactory.createProxy(Messages.class, new ApplicationMessagesObjectCreator(),
"<ApplicationMessagesProxy>");
// Listen for invalidations; clear our cache of localized Messages bundles when
// and invalidation occurs.
messagesSource.getInvalidationEventHub().addInvalidationListener(this);
}
return proxy;
}
public <T> T provide(Class<T> objectType, AnnotationProvider annotationProvider, ObjectLocator locator)
{
if (objectType.equals(Messages.class))
return objectType.cast(getProxy());
return null;
}
public void objectWasInvalidated()
{
localeToMessages.clear();
}
}