class ClassUtil {

    public final static String[] getProtectedField(String className) {
        Class classz = loadClass(className);
        Set<String> set = new HashSet<>();
        Field[] fields = classz.getDeclaredFields();
        if (fields != null) {
            for (Field f : fields) {
                String modifier = Modifier.toString(f.getModifiers());
                if (modifier.startsWith("protected")) {
                    set.add(f.getName());
                }
            }
        }
        return set.toArray(new String[set.size()]);
    }

}