// Copyright 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 org.apache.tapestry.services.ApplicationStateCreator;
import org.apache.tapestry.services.ApplicationStatePersistenceStrategy;
import org.apache.tapestry.services.Request;
import org.apache.tapestry.services.Session;
/**
* Stores ASOs in the {@link Session}, which will be created as necessary.
* <p>
* TODO: Re-storing the object back into the session at the end of the request. That's going to
* require some kind of end-of-request notification.
*/
public class SessionApplicationStatePersistenceStrategy implements
ApplicationStatePersistenceStrategy
{
static final String PREFIX = "aso:";
private final Request _request;
public SessionApplicationStatePersistenceStrategy(Request request)
{
_request = request;
}
private Session getSession()
{
return _request.getSession(true);
}
@SuppressWarnings("unchecked")
public <T> T get(Class<T> asoClass, ApplicationStateCreator<T> creator)
{
Session session = getSession();
String key = buildKey(asoClass);
T aso = (T) session.getAttribute(key);
if (aso == null)
{
aso = creator.create();
session.setAttribute(key, aso);
}
return aso;
}
private <T> String buildKey(Class<T> asoClass)
{
return PREFIX + asoClass.getName();
}
public <T> void set(Class<T> asoClass, T aso)
{
String key = buildKey(asoClass);
getSession().setAttribute(key, aso);
}
public <T> boolean exists(Class<T> asoClass)
{
String key = buildKey(asoClass);
Session session = _request.getSession(false);
return session != null && session.getAttribute(key) != null;
}
}