php用于URL的base64

        function base64url_encode($plainText) {

            $base64 = base64_encode($plainText);
            $base64url = strtr($base64, '+/=', '-_,');
            return $base64url;   
        }

        function base64url_decode($plainText) {

            $base64url = strtr($plainText, '-_,', '+/=');
            $base64 = base64_decode($base64url);
            return $base64;   
        }