查找包下所有的类

包括二级包,classes和jar的情况都考虑

/**
	 * 获得包下的类
	 * 
	 * @param packageName
	 *            The base package
	 * @return The classes
	 * @throws ClassNotFoundException
	 * @throws IOException
	 */
	public static Class[] getClasses(String packageName)
			throws ClassNotFoundException, IOException {
		ClassLoader classLoader = Thread.currentThread()
				.getContextClassLoader();
		assert classLoader != null;
		String path = packageName.replace('.', '/');
		Enumeration<URL> resources = classLoader.getResources(path);
		List<File> dirs = new ArrayList<File>();
		ArrayList<Class> classes = new ArrayList<Class>();
		while (resources.hasMoreElements()) {
			URL resource = resources.nextElement();
			String p = "";
			if (resource.getFile().indexOf("!") >= 0) {// 在其他的jar文件中
				p = resource.getFile().substring(0,
						resource.getFile().indexOf("!")).replaceAll("%20", "");
			} else {// 在classes目录中
				p = resource.getFile();
			}
			if (p.startsWith("file:/"))
				p = p.substring(6);
			if (p.toLowerCase().endsWith(".jar")) {

				JarFile jarFile = new JarFile(p);
				Enumeration<JarEntry> enums = jarFile.entries();
				while (enums.hasMoreElements()) {
					JarEntry entry = (JarEntry) enums.nextElement();
					String n = entry.getName();

					if (n.endsWith(".class")) {
						n = n.replaceAll("/", ".").substring(0, n.length() - 6);
						if (n.startsWith(packageName)) {

							classes.add(Class.forName(n));

						}
					}

				}
			} else {
				dirs.add(new File(p));
			}

		}

		for (File directory : dirs) {
			classes.addAll(findClasses(directory, packageName));
		}
		return classes.toArray(new Class[classes.size()]);
	}

	/**
	 * 查找一个文件夹下的文件
	 * 
	 * @param directory
	 *            The base directory
	 * @param packageName
	 *            The package name for classes found inside the base directory
	 * @return The classes
	 * @throws ClassNotFoundException
	 */
	public static List<Class> findClasses(File directory, String packageName)
			throws ClassNotFoundException {
		List<Class> classes = new ArrayList<Class>();
		if (!directory.exists()) {
			return classes;
		}
		File[] files = directory.listFiles();
		for (File file : files) {
			if (file.isDirectory()) {
				assert !file.getName().contains(".");
				classes.addAll(findClasses(file, packageName + "."
						+ file.getName()));
			} else if (file.getName().endsWith(".class")) {
				classes.add(Class.forName(packageName
						+ '.'
						+ file.getName().substring(0,
								file.getName().length() - 6)));
			}
		}
		return classes;
	}