php获取微信的openid

        header("Content-type: text/html; charset=utf-8");
        if(!isset($_GET['code'])){
            $APPID='公众号在微信的appid';
            $REDIRECT_URI='要请求的url';
            $scope='snsapi_base';
            $url='https://open.weixin.qq.com/connect/oauth2/authorize?appid='.$APPID.'&redirect_uri='.urlencode($REDIRECT_URI).'&response_type=code&scope='.$scope.'&state=wx'.'#wechat_redirect';
            header("Location:".$url);
        }else{
            $appid = "公众号在微信的appid";
            $secret = "公众号在微信的app secret";
            $code = $_GET["code"];
            $get_token_url = 'https://api.weixin.qq.com/sns/oauth2/access_token?appid='.$appid.'&secret='.$secret.'&code='.$code.'&grant_type=authorization_code';
            $ch = curl_init();
            curl_setopt($ch,CURLOPT_URL,$get_token_url);
            curl_setopt($ch,CURLOPT_HEADER,0);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1 );
            curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
            $res = curl_exec($ch);
            curl_close($ch);
            $json_obj = json_decode($res,true);
            //根据openid和access_token查询用户信息
            $access_token = $json_obj['access_token'];
            $openid = $json_obj['openid'];
            $get_user_info_url = 'https://api.weixin.qq.com/sns/userinfo?access_token='.$access_token.'&openid='.$openid.'&lang=zh_CN';
            
            $ch = curl_init();
            curl_setopt($ch,CURLOPT_URL,$get_user_info_url);
            curl_setopt($ch,CURLOPT_HEADER,0);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1 );
            curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
            $res = curl_exec($ch);
            curl_close($ch);
            
            //解析json
            $user_obj = json_decode($res,true);
            $_SESSION['user'] = $user_obj;
            print_r($user_obj);
        }