private File getTarget(File f, File targetDir) {
		File target = new File(targetDir, f.getAbsolutePath().substring(getPath().getAbsolutePath().length()));		
		if (!target.getParentFile().exists() && !target.getParentFile().mkdirs()) {
			throw new RuntimeException("Cannot create target path " + target.getParent());
		}
		return target;
	}