Android 根据包名获得名下所有类

要将一些class存放在某固定的包名下，通过反射实例化出来，

private List getClasses(Context mContext, String packageName) {
        ArrayList classes = new ArrayList<>();
        try {
            String packageCodePath = mContext.getPackageCodePath();
            DexFile df = new DexFile(packageCodePath);
            String regExp = "^" + packageName + ".\\w+$";
            for (Enumeration iter = df.entries(); iter.hasMoreElements(); ) {
                String className = iter.nextElement();
                if (className.matches(regExp)) {
                    classes.add(className);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return classes;
}