PHP 获取微信小程序用户OPENID

<?php
    /**
     * desc: 获取小程序用户openid
     */
    function getOpenid($appid,$appSecret,$code) {
        $code = $code;//小程序传来的code值
        $appid = $appid;//小程序的appid
        $appSecret = $appSecret;// 小程序的$appSecret
        $wxUrl = 'https://api.weixin.qq.com/sns/jscode2session?appid=%s&secret=%s&js_code=%s&grant_type=authorization_code';
        $getUrl = sprintf($wxUrl, $appid, $appSecret, $code);//把appid，appsecret，code拼接到url里
        $result = curl_get($getUrl);//请求拼接好的url
        $wxResult = json_decode($result, true);
        if (empty($wxResult)) {
            echo '获取openid时异常，微信内部错误';
        } else {
            $loginFail = array_key_exists('errcode', $wxResult);
            if ($loginFail) {//请求失败
                var_dump($wxResult);
            } else {//请求成功
                $openid = $wxResult['openid'];
                echo $openid;
            }
        }
    }

    //php请求网络的方法
    function curl_get($url, &$httpCode = 0) {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

        //不做证书校验,部署在linux环境下请改为true
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
        $file_contents = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);
        return $file_contents;
    }

    getOpenid('AccessKeyId','AccessKeySecret',$_GET['code']);
?>