f@0: /*  
f@0:  CCmI Editor - A Collaborative Cross-Modal Diagram Editing Tool
f@0: 	  
f@0:  Copyright (C) 2002 Cay S. Horstmann (http://horstmann.com)
f@0:  Copyright (C) 2011  Queen Mary University of London (http://ccmi.eecs.qmul.ac.uk/)
f@0: 
f@0:  This program is free software: you can redistribute it and/or modify
f@0:  it under the terms of the GNU General Public License as published by
f@0:  the Free Software Foundation, either version 3 of the License, or
f@0:  (at your option) any later version.
f@0: 
f@0:  This program is distributed in the hope that it will be useful,
f@0:  but WITHOUT ANY WARRANTY; without even the implied warranty of
f@0:  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
f@0:  GNU General Public License for more details.
f@0: 
f@0:  You should have received a copy of the GNU General Public License
f@0:  along with this program.  If not, see <http://www.gnu.org/licenses/>.
f@0: */
f@0: 
f@0: package uk.ac.qmul.eecs.ccmi.utils;
f@0: 
f@0: import java.util.prefs.Preferences;
f@0: 
f@0: /**
f@0:  * A service for storing and loading user preferences.
f@0:  */
f@0: public abstract class PreferencesService
f@0: {
f@0:    /**
f@0:     * Gets an instance of the service, suitable for the package of the given class.
f@0:     * @return an instance of the service
f@0:     */
f@0:    public static PreferencesService getInstance(){
f@0:       if (service != null) return service;
f@0:       try{
f@0:          service = new DefaultPreferencesService();
f@0:          return service;
f@0:       }
f@0:       catch (SecurityException exception){
f@0:          throw new RuntimeException(exception);      
f@0:       }
f@0:    }
f@0:    
f@0:    /**
f@0:     * Gets a previously stored string from the service.
f@0:     * @param key the key of the string
f@0:     * @param defval the value to return if no matching value was found
f@0:     * @return the value stored with the given key, or defval if none was found 
f@0:     */
f@0:    public abstract String get(String key, String defval);
f@0:    /**
f@0:     * Saves a key/value pair for later retrieval.
f@0:     * @param key the key of the string to be stored
f@0:     * @param value the value to to be stored
f@0:     */
f@0:    public abstract void put(String key, String value);
f@0:    
f@0:    private static PreferencesService service;
f@0: }
f@0: 
f@0: /**
f@0:  * The default preferences service that uses the java.util.prefs API. 
f@0:  */
f@0: class DefaultPreferencesService extends PreferencesService{   
f@0: 
f@0: 	public DefaultPreferencesService(){
f@0: 		prefs = Preferences.userNodeForPackage(this.getClass());   
f@0: 	}
f@0: 
f@0: 	@Override
f@0: 	public String get(String key, String defval) { return prefs.get(key, defval); }
f@0: 	@Override
f@0: 	public void put(String key, String defval) { prefs.put(key, defval); }
f@0: 
f@0: 	private Preferences prefs;
f@0: }