public void init(final FilterConfig config) throws ServletException {
        servletContext = config.getServletContext();

        encoding = config.getInitParameter(LastaPrepareFilter.ENCODING_KEY);
        if (encoding == null) {
            encoding = LastaPrepareFilter.DEFAULT_ENCODING;
        }

        // ex. sjis:Shift_JIS,eucjp:EUC-JP
        final String value = config.getInitParameter(ENCODING_MAP);