001/*
002 * Syncany, www.syncany.org
003 * Copyright (C) 2011-2016 Philipp C. Heckel <philipp.heckel@gmail.com> 
004 *
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU General Public License as published by
007 * the Free Software Foundation, either version 3 of the License, or
008 * (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 * GNU General Public License for more details.
014 *
015 * You should have received a copy of the GNU General Public License
016 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017 */
018package org.syncany.cli;
019
020import java.util.logging.Level;
021import java.util.logging.Logger;
022
023import org.syncany.util.StringUtil;
024
025/**
026 * The command factory can be used to instantiate a new command from a  
027 * command name. The {@link CommandLineClient} uses this class to create
028 * and run commands by mapping a command argument to a corresponding
029 * {@link Command} class.
030 * 
031 * @author Philipp C. Heckel (philipp.heckel@gmail.com)
032 */
033public class CommandFactory {
034        private static final Logger logger = Logger.getLogger(CommandFactory.class.getSimpleName());
035        
036        /**
037         * Maps the given command name to a corresponding {@link Command} class and 
038         * instantiates it. The command name is camel-cased and mapped to a FQCN.
039         * 
040         * <p>Example: The command 'ls-remote' is mapped to the FQCN
041         * <code>org.syncany.cli.LsRemoteCommand</code>.
042         * 
043         * @param commandName Command name, e.g. ls-remote or init
044         * @return Returns a <code>Command</code> instance, or <code>null</code> if the command name cannot be mapped to a class
045         */
046        public static Command getInstance(String commandName) {
047                String thisPackage = CommandFactory.class.getPackage().getName();
048                String camelCaseCommandName = StringUtil.toCamelCase(commandName);
049                String fqCommandClassName = thisPackage+"."+camelCaseCommandName+Command.class.getSimpleName();
050                
051                // Try to load!
052                try {
053                        Class<?> commandClass = Class.forName(fqCommandClassName);
054                        return (Command) commandClass.newInstance();
055                } 
056                catch (Exception ex) {
057                        logger.log(Level.INFO, "Could not find operation FQCN " + fqCommandClassName, ex);
058                        return null;
059                }               
060        }
061}