参考腾讯云官方文档：

人脸核身 获取 Access Token_腾讯云

public function getAccessToken(){
		

        $data = [
            'appId' => '', //WBappid,https://cloud.tencent.com/document/product/1007/49634
            'secret' => '',
	        'grant_type' => 'client_credential', //授权类型
            'version' => '1.0.0'
        ];

        $str = http_build_query($data);

        $url = 'https://kyc1.qcloud.com/api/oauth2/access_token?'.$str;

        $result = $this->cmf_curl_get($url);

        $access_token = '';

        $arr = json_decode($result,true);
        if($arr['code'] == 0){
            $access_token = $arr['access_token'];
            // 存入磁盘  
            file_put_contents('/data/config/tx_face_accesstoken.txt',$access_token);
        }


}

function cmf_curl_get($url){
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FAILONERROR, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_AUTOREFERER, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_TIMEOUT, 5);
    $SSL = substr($url, 0, 8) == "https://" ? true : false;
    if ($SSL) {
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); // 信任任何证书
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2); // 检查证书中是否设置域名
    }
    $content = curl_exec($ch);
    curl_close($ch);
    return $content;
}