curl的json格式请求

public static function cjPost($url, $data = NULL, $json = false)
    {
        $curl = curl_init();
        curl_setopt($curl, CURLOPT_URL, $url);
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);

        if (!empty($data)) {
            if ($json && is_array($data)) {
                $data = json_encode($data);
            }
            curl_setopt($curl, CURLOPT_POST, 1);
            curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
            if ($json) {
                // 发送JSON数据
                curl_setopt($curl, CURLOPT_HEADER, 0);
                curl_setopt($curl, CURLOPT_HTTPHEADER,
                    array(
                        'Content-Type: application/json; charset=utf-8',
                        'Content-Length:' . strlen($data)
                    )
                );
            }
        }

        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        $res = curl_exec($curl);
        var_export($res);die;
        $errorno = curl_errno($curl);

        if ($errorno) {
            return array('errorno' => false, 'errmsg' => $errorno);
        }
        curl_close($curl);

        return json_decode($res, true);
    }