public function getCaptcha($path)
    {
        $url = Config::get('url.login_captcha');
        $cookie = new CookieJar();
        $codePath = $path . sha1($this->getUsername() . '-' . microtime(true)) . '.gif';
        $options = ['cookies' => $cookie, 'save_to' => $codePath];

        $response = $this->request('get', [$url, [], $options]);

        // Check the StatusCode
        if ($response->getStatusCode() == 200) {
            throw new HttpException('get the captcha failed!', 10005);
        }

        return $codePath;
    }