src/org/sonews/daemon/CommandSelector.java
author František Kučera <franta-hg@frantovo.cz>
Sun Oct 16 22:36:46 2011 +0200 (2011-10-16)
changeset 82 21f413541357
parent 35 ed84c8bdd87b
permissions -rwxr-xr-x
Drupal: tidy, odstavce, XSLT
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/*
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 *   SONEWS News Server
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 *   see AUTHORS for the list of contributors
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 *
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 *   This program is free software: you can redistribute it and/or modify
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 *   it under the terms of the GNU General Public License as published by
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 *   the Free Software Foundation, either version 3 of the License, or
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 *   (at your option) any later version.
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 *
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 *   This program is distributed in the hope that it will be useful,
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 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
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 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 *   GNU General Public License for more details.
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 *
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 *   You should have received a copy of the GNU General Public License
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 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
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 */
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package org.sonews.daemon;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.Set;
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import java.util.concurrent.ConcurrentHashMap;
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import org.sonews.daemon.command.Command;
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import org.sonews.daemon.command.UnsupportedCommand;
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import org.sonews.util.Log;
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import org.sonews.util.io.Resource;
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/**
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 * Selects the correct command processing class.
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 * @author Christian Lins
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 * @since sonews/1.0
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 */
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public class CommandSelector
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{
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	private static Map<Thread, CommandSelector> instances = new ConcurrentHashMap<Thread, CommandSelector>();
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	private static Map<String, Class<?>> commandClassesMapping = new ConcurrentHashMap<String, Class<?>>();
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	static {
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		String[] classes = Resource.getAsString("helpers/commands.list", true).split("\n");
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		for (String className : classes) {
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			if (className.charAt(0) == '#') {
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				// Skip comments
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				continue;
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			}
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			try {
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				addCommandHandler(className);
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			} catch (ClassNotFoundException ex) {
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				Log.get().warning("Could not load command class: " + ex);
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			} catch (InstantiationException ex) {
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				Log.get().severe("Could not instantiate command class: " + ex);
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			} catch (IllegalAccessException ex) {
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				Log.get().severe("Could not access command class: " + ex);
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			}
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		}
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	}
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	public static void addCommandHandler(String className)
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		throws ClassNotFoundException, InstantiationException,
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		IllegalAccessException
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	{
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		Class<?> clazz = Class.forName(className);
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		Command cmd = (Command) clazz.newInstance();
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		String[] cmdStrs = cmd.getSupportedCommandStrings();
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		for (String cmdStr : cmdStrs) {
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			commandClassesMapping.put(cmdStr, clazz);
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		}
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	}
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	public static Set<String> getCommandNames()
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	{
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		return commandClassesMapping.keySet();
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	}
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	public static CommandSelector getInstance()
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	{
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		CommandSelector csel = instances.get(Thread.currentThread());
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		if (csel == null) {
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			csel = new CommandSelector();
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			instances.put(Thread.currentThread(), csel);
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		}
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		return csel;
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	}
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	private Map<String, Command> commandMapping = new HashMap<String, Command>();
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	private Command unsupportedCmd = new UnsupportedCommand();
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	private CommandSelector()
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	{
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	}
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	public Command get(String commandName)
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	{
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		try {
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			commandName = commandName.toUpperCase();
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			Command cmd = this.commandMapping.get(commandName);
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			if (cmd == null) {
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				Class<?> clazz = commandClassesMapping.get(commandName);
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				if (clazz == null) {
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					cmd = this.unsupportedCmd;
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				} else {
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					cmd = (Command) clazz.newInstance();
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					this.commandMapping.put(commandName, cmd);
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				}
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			} else if (cmd.isStateful()) {
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				cmd = cmd.getClass().newInstance();
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			}
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			return cmd;
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		} catch (Exception ex) {
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			ex.printStackTrace();
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			return this.unsupportedCmd;
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		}
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	}
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}