sina::checkUser PHP Method

    public function checkUser()
    {
        if (isset($_REQUEST['code'])) {
            $keys = array();
            $keys['code'] = $_REQUEST['code'];
            $keys['redirect_uri'] = U('public/Widget/displayAddons', array('type' => $_REQUEST['type'], 'addon' => 'Login', 'hook' => 'no_register_display'));
            try {
                $token = $this->_oauth->getAccessToken('code', $keys);
            } catch (OAuthException $e) {
                $token = null;
            }
        } else {
            $keys = array();
            $keys['refresh_token'] = $_REQUEST['code'];
            try {
                $token = $this->_oauth->getAccessToken('token', $keys);
            } catch (OAuthException $e) {
                $token = null;
            }
        }
        if ($token) {
            setcookie('weibojs_' . $this->_oauth->client_id, http_build_query($token));
            $_SESSION['sina']['access_token']['oauth_token'] = $token['access_token'];
            $_SESSION['sina']['access_token']['oauth_token_secret'] = $token['refresh_token'];
            $_SESSION['sina']['expire'] = time() + $token['expires_in'];
            $_SESSION['sina']['uid'] = $token['uid'];
            $_SESSION['open_platform_type'] = 'sina';
            return $token;
        } else {
            return false;
        }
    }

 public function callback()
 {
     include_once SITE_PATH . '/addons/plugins/login/sina.class.php';
     $sina = new sina();
     $sina->checkUser();
     redirect(U('home/public/otherlogin'));
 }