Package Scanner for Active Objects

PackageScanner.java

package com.pocketgator.placeholder.common;

import java.io.File;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import net.java.ao.RawEntity;

public class PackageScanner {
	public static Class<? extends RawEntity<?>>[] getClassesInPackage(
			String pckgname) {
		File directory = getPackageDirectory(pckgname);
		if (!directory.exists()) {
			throw new IllegalArgumentException(
					"Could not get directory resource for package " + pckgname
							+ ".");
		}

		return getClassesInPackage(pckgname, directory);
	}

	private static Class<? extends RawEntity<?>>[] getClassesInPackage(
			String pckgname,
			File directory) {
		List<Class<?>> classes = new ArrayList<Class<?>>();
		for (String filename : directory.list()) {
			if (filename.endsWith(".class")) {
				String classname = buildClassname(pckgname, filename);
				try {
					Class<?> classToAdd = Class.forName(classname);
					if (classToAdd.isInterface()
							&& classToAdd != RawEntity.class
							&& RawEntity.class.isAssignableFrom(classToAdd)) {
						classes.add(Class.forName(classname));
					}
				} catch (ClassNotFoundException e) {
					System.err.println("Error creating class " + classname);
				}
			}
		}
		return classes.toArray(new Class[classes.size()]);
	}

	private static String buildClassname(String pckgname, String filename) {
		return pckgname + '.' + filename.replace(".class", "");
	}

	private static File getPackageDirectory(String pckgname) {
		ClassLoader cld = Thread.currentThread().getContextClassLoader();
		if (cld == null) {
			throw new IllegalStateException("Can't get class loader.");
		}

		URL resource = cld.getResource(pckgname.replace('.', '/'));
		if (resource == null) {
			throw new RuntimeException("Package " + pckgname
					+ " not found on classpath.");
		}

		return new File(resource.getFile());
	}

}