DeviceLoaderJava.java

/*
Mjdj MIDI Morph - an extensible MIDI processor and translator.
Copyright (C) 2010 Confusionists, LLC (www.confusionists.com)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 

See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. 

You may contact the author at mjdj_midi_morph [at] confusionists.com
*/
package com.confusionists.mjdj.fileIO;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.List;

import com.confusionists.mjdj.ui.Logger;
import com.confusionists.mjdjApi.midiDevice.ReceiverDeviceWrapper;
import com.confusionists.mjdjApi.midiDevice.TransmitterDeviceWrapper;
import com.confusionists.util.RecursiveFileList;

public class DeviceLoaderJava {
	/**
	 * let's be serious, this is single-threaded so it can be static
	 */
	private static ClassLoader classLoader; 

	public void load(List<TransmitterDeviceWrapper> transmitters, List<ReceiverDeviceWrapper> receivers) {
		try {
			// get all .class files in the directory
			File path = ExternalDirectories.instance.devicesDir;
			load(path, transmitters, receivers);
		} catch (Exception e) {
			Logger.log("Problem loading devices", e);

		}

	}

	private URL[] getClasspath() throws MalformedURLException {
		URL url = ExternalDirectories.instance.devicesDir.toURI().toURL();
		URL[] urls = { url };
		return urls;
	}

	private void load(File path, List<TransmitterDeviceWrapper> transmitters, List<ReceiverDeviceWrapper> receivers) throws Exception {
		if (path == null)
			throw new NullPointerException("very null");
		if (!path.exists()) {
			throw new RuntimeException("Sorry, can't find the plugins directory, should be " + path.getAbsolutePath());
		} else {
			System.out.println("Found and loading " + path.getAbsolutePath());
		}

		File[] classFiles = RecursiveFileList.getList(path, "class");

		URL[] urls = getClasspath();
		classLoader = new URLClassLoader(urls);

		for (File classFile : classFiles) {
			String totalPath = classFile.getAbsolutePath();
			totalPath = totalPath.substring(path.getAbsolutePath().length()); // get rid of the root
			String className = totalPath.substring(totalPath.lastIndexOf(File.separatorChar) + 1);
			className = className.substring(0, className.length() - ".class".length());
			String packagePrefix;
			int lastSeparator = totalPath.lastIndexOf(File.separatorChar);
			if (lastSeparator != -1) {
				packagePrefix = totalPath.substring(0, lastSeparator + 1);
			} else
				packagePrefix = "";

			packagePrefix = packagePrefix.replace(File.separatorChar, '.');
			if (packagePrefix.startsWith("."))
				packagePrefix = packagePrefix.substring(1);

			className = packagePrefix + className;
			Class<?> clazz;
			clazz = classLoader.loadClass(className);
			try {
				
				Object obj = clazz.newInstance();

				if (obj instanceof ReceiverDeviceWrapper) {
					ReceiverDeviceWrapper receiver = (ReceiverDeviceWrapper) obj;
					Logger.log("Loaded receiver " + receiver.getName());
					receivers.add(receiver);
				} else if (obj instanceof TransmitterDeviceWrapper) {
					TransmitterDeviceWrapper transmitter = (TransmitterDeviceWrapper) clazz.newInstance();
					Logger.log("Loaded transmitter " + transmitter.getName());
					transmitters.add(transmitter);
				}
			} catch (InstantiationException e) {
				// Logger.log("Could not instantiate device " + className +
				// " probably abstract");
			} catch (IllegalAccessException e) {
				//Logger.log("Could not instantiate device " + className + " probably private");
			} catch (Exception e) {
				Logger.log("Could not instantiate device " + className, e);
			}
		}
	}

	/* testing main */
	public static void main(String[] args) throws Exception {

	}

}