class ExtendStaticRepository implements StaticRepository {
    private File location;

    public ExtendStaticRepository() {
        File folder = ExtendLoader.folder();
        if (folder == null) {
            throw new IllegalStateException("No extension directory exists");
        }

        location = new File(folder, "static");
    }

    /**
     * @param relativePath 例：demo/file.htm （没有'/'开头）
     */
    @Override
    public URL find(String relativePath) throws Exception {<FILL_FUNCTION_BODY>}
}

        File file = new File(location, relativePath);

        if (file.exists()) {
            return file.toURI().toURL();
        } else {
            return null;
        }
    
<no_super_class>