private String safe (String src) {
        StringBuffer sb = new StringBuffer ();
        for (int i = 0; i < src.length (); i++) {
            char c = src.charAt (i);
            if (c >= 32 && c < 128) {
                sb.append (c);
            } else {
                sb.append ("<" + (int) c + ">");
            }
        }
        return sb.toString ();
    }