微信取得用户是否关注公众号函数

public function getUserInfo() {

         $bianhao = I('get.bianhao');
       
//        echo '<strong style="color:#ff0000">订单号<span >'.$bianhao.'</span></strong>';
        $appid = 'xxxxxxxxxxxxx';
        $appsecret = 'xxxxxxxxxxxxxxxxxxxxxxxxxxx';
        $code = $_GET["code"];
        $this->assign('code', $code);
//        show_bug($code,"code");
//echo $code;
//第一步:取全局access_token
        $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=" . $appid . "&secret=" . $appsecret;
        $token = getJson($url);
//        show_bug($token,"token");
//        echo $token["access_token"];
//第二步:取得openid
        $oauth2Url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=" . $appid . "&secret=" . $appsecret . "&code=" . $code . "&grant_type=authorization_code";
        $oauth2 = getJson($oauth2Url);
//        show_bug($oauth2,"oauth2");

//第三步:根据全局access_token和openid查询用户信息  
        $access_token = $token["access_token"];
        $openid = $oauth2['openid'];
//        show_bug($openid,"openid");
        $_SESSION['o'] = $openid;
//                echo $_SESSION['o']."这是O<br>";
        $get_user_info_url = "https://api.weixin.qq.com/cgi-bin/user/info?access_token=" . $access_token . "&openid=" . $_SESSION['o'] . "&lang=zh_CN";
        $userinfo = getJson($get_user_info_url);
//        show_bug($userinfo,"userinfo");
//echo $openid;
//打印用户信息
        $subscribe = intval($userinfo['subscribe']);
    if($_SESSION['o']){
        if ($subscribe==1) {

            $guanzhu="-100%";
//            show_bug($guanzhu,"你已经关注");
            $this->assign('guanzhu',$guanzhu);
            $this->assign('bianhao', $bianhao);
//            $this->display("Order/index");
            $this->display("Order/getUserInfo");
        } else {
            $guanzhu="0";
//            show_bug($guanzhu,"你没有关注");
            $this->assign('bianhao', $bianhao);
            $this->assign('guanzhu',$guanzhu);
//            $this->display("Order/getUserInfo");
            $this->display("Order/index");
        }
    }else  {
//        show_bug("微信seesion断开");
         $this->assign('bianhao', $bianhao);
        $this->display("Order/index");
    }  
        
    }