CommandManager.java

class CommandManager {
	private Plugin plugin;
	private Map<String, Class<? extends ICommandable>> commands = new Hashtable<String, Class<? extends ICommandable>>();
	
	public CommandManager(Plugin plugin) {
		this.plugin = plugin;
	}
	
	public void loadFromDescription(PluginDescriptionFile desc, ClassLoader loader) {
		Object object = desc.getCommands();
		if (object == null)
			return;
		
		@SuppressWarnings("unchecked")
		Map<String, Map<String, Object>> map = (Map<String, Map<String, Object>>) object;
		
		for (Entry<String, Map<String, Object>> entry : map.entrySet()) {
			String label = entry.getKey();
			String classname = entry.getValue().get("class").toString();
			
			try {
				Class<?> klass = Class.forName(classname, true, loader);
				Class<? extends ICommandable> commandClass = klass.asSubclass(ICommandable.class);
				addCommand(label, commandClass);
			} catch (ClassNotFoundException e) {
				System.out.println("Unable to load command class for command /" + label);
			} 
		}
	}
	
	public void addCommand(String label, Class<? extends ICommandable> klass) {
		commands.put(label, klass);
	}
	
	public boolean dispatch(Player player, Command command, String label, String[] args) {
		if (!commands.containsKey(label))
			return false;
		
		boolean handled = true;
		
		Class<? extends ICommandable> klass = commands.get(label);
		try {
			Constructor<? extends ICommandable> ctor = klass.getConstructor(Plugin.class);
			ICommandable c = ctor.newInstance(plugin);
			handled = c.onCommand(player, command, label, args);
		} catch (NoSuchMethodException e) {
			System.out.println("No constructor that accepts a Plugin.");
		} catch (InstantiationException e) {
			System.out.println("Error while creating a Commandable object.");
		} catch (IllegalAccessException e) {
			System.out.println("Illegal access to the Commandable object constructor.");
		} catch (InvocationTargetException e) {
			System.out.println(e.getCause().getMessage());
		}
		
		return handled;
	}
}

ICommandable.java

public interface ICommandable {
	boolean onCommand(Player player, Command command, String label, String[] args);
}

plugin.yml

name: Tester
main: com.jonathan.minecraft.Tester.Tester
version: 1.00
commands:
  test:
    class: com.jonathan.minecraft.Tester.commands.TestCommand
    description: Displays a test message.
    usage: /<command>

Tester.java

public class Tester extends JavaPlugin {
	private CommandManager manager = new CommandManager(this);
	
	public Waypoint(PluginLoader pluginLoader, Server instance,
			PluginDescriptionFile desc, File folder, File plugin,
			ClassLoader cLoader) {
		super(pluginLoader, instance, desc, folder, plugin, cLoader);
		
		manager.loadFromDescription(desc, cLoader);
	}
	
	@Override
	public boolean onCommand(Player player, Command command, String label, String[] args) {
		return manager.dispatch(player, command, label, args);
	}
	
	@Override
	public void onEnable() {
	}
	
	@Override
	public void onDisable() {
	}
}