/* ********************************************************************** **
** Copyright notice **
** **
** (c) 2005-2009 RSSOwl Development Team **
** http://www.rssowl.org/ **
** **
** All rights reserved **
** **
** This program and the accompanying materials are made available under **
** the terms of the Eclipse Public License v1.0 which accompanies this **
** distribution, and is available at: **
** http://www.rssowl.org/legal/epl-v10.html **
** **
** A copy is found in the file epl-v10.html and important notices to the **
** license from the team is found in the textfile LICENSE.txt distributed **
** in this package. **
** **
** This copyright notice MUST APPEAR in all copies of the file! **
** **
** Contributors: **
** RSSOwl Development Team - initial API and implementation **
** **
** ********************************************************************** */
package org.rssowl.core.persist.dao;
import org.rssowl.core.persist.IModelFactory;
import org.rssowl.core.persist.IPreference;
import org.rssowl.core.persist.event.PreferenceEvent;
import org.rssowl.core.persist.event.PreferenceListener;
import org.rssowl.core.persist.service.PersistenceException;
/**
* The <code>IPreferenceDAO</code> offers methods to store and retrieve
* Preferences, simply by providing a Key-Value-Pair. The underlying persistance
* layer is responsible for how the Values are stored.
*
* @author bpasero
*/
public interface IPreferenceDAO extends IEntityDAO<IPreference, PreferenceListener, PreferenceEvent> {
/**
* If a IPreference with <code>key</code> exists in the persistence system,
* it is loaded and returned. Otherwise, <code>null</code> is returned.
*
* @param key The key of the required IPreference.
* @return a IPreference with the given key.
* @throws PersistenceException If an error occurs while trying to retrieve
* the object from the persistence system.
*/
IPreference load(String key) throws PersistenceException;
/**
* If a IPreference with <code>key</code> exists in the persistence system,
* loads it and returns it. Otherwise, creates a new IPreference with
* <code>key</code> and returns it.
*
* @param key The key that uniquely identified the IPreference.
* @return An existing or newly created IPreference object.
* @throws PersistenceException If an error occurs while trying to retrieve
* the object from the persistence system.
* @see #load(String)
* @see IModelFactory#createPreference(String)
*/
IPreference loadOrCreate(String key) throws PersistenceException;
/**
* If the persistence layer contains a preference with a key that matches
* <code>key</code>, the preference is deleted and <code>true</code> is
* returned. Otherwise, no action is taken and <code>false</code> is
* returned.
*
* @param key The key under which the value is stored.
* @return <code>true</code> if a preference exists with key matching
* <code>key</code>. <code>false</code> otherwise.
* @throws PersistenceException In case of an error while accessing the
* persistance layer.
*/
boolean delete(String key) throws PersistenceException;
}