protected function sendTextMsgToJsonString(WxSendTextMsg $msg)
    {
        $formatStr = '{
                        "touser":"%s",
                        "msgtype":"%s",
                        "text":
                        {
                             "content":"%s"
                        }
                    }';
        $result = sprintf($formatStr,   $msg->getToUserName(),
                                        $msg->getMsgType(),
                                        $msg->getContent()
                        );


        return $result;
    }