class Withdraw

{

    public $mchid = '你的商户id';

    public $appid = '小程序appid';

    public $serial_no = '你的证书序列号'; // 证书序列号，不知道怎么获取的看上面的图

    public function transfer($openid, $trade_no, $money, $desc='备注说明')

    {

        $money = (int)($money * 100);

        $post_data = [

            "appid" => $this->appid,//appid

            "out_batch_no" => $trade_no,//商家批次单号

            "batch_name" => $desc,//批次名称

            "batch_remark" => $desc,//批次备注

            "total_amount" => $money,// 转账金额单位为“分”

            "total_num" => 1, // 转账总笔数

            //此处可以多笔提现  组合二维数组放到transfer_detail_list即可   我这里单笔操作，写死了

            "transfer_detail_list" => [

                [

                    'out_detail_no' => $trade_no,

                    'transfer_amount' => $money,

                    'transfer_remark' => $desc,

                    'openid' => $openid,

                ]

            ]

        ];

        $url = 'https://api.mch.weixin.qq.com/v3/transfer/batches';

        //JSON_UNESCAPED_SLASHES|JSON_UNESCAPED_UNICODE  防止中文被转义

        $result = $this->wx_post($url, json_encode($post_data, JSON_UNESCAPED_SLASHES|JSON_UNESCAPED_UNICODE));

        $result = json_decode($result, true);

        if (isset($result['prepay_id'])) {

            return $result['prepay_id'];

        }

        return $result;

    }

    /**post请求

     * @param $url

     * @param $param

     * @return bool|string

     */

    private function wx_post($url, $param)

    {

        $authorization = $this->getV3Sign($url, "POST", $param);

        $curl = curl_init();

        $headers = [

            'Authorization:' . $authorization,

            'Accept:application/json',

            'Content-Type:application/json;charset=utf-8',

            'User-Agent:Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36',

        ];

        curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);

        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

        curl_setopt($curl, CURLOPT_TIMEOUT, 500);

        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);

        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);

        curl_setopt($curl, CURLOPT_URL, $url);

        curl_setopt($curl, CURLOPT_POSTFIELDS, $param);

        curl_setopt($curl, CURLOPT_POST, true);

        $res = curl_exec($curl);

        curl_close($curl);

        return $res;

    }

    /**

     * 微信提现V3签名

     * @param $url

     * @param $http_method

     * @param $body

     * @return string

     */

    private function getV3Sign($url, $http_method, $body)

    {

        $nonce = strtoupper($this->createNonceStr(32));

        $timestamp = time();

        $url_parts = parse_url($url);

        $canonical_url = ($url_parts['path'] . (!empty($url_parts['query']) ? "?${url_parts['query']}" : ""));

        $cert_dir = ROOT_PATH.DS."config".DS."payment_cert".DS."wechatpay".DS;

        $sslKeyPath = $cert_dir."apiclient_key.pem";

        //拼接参数

        $message = $http_method . "\n" .

            $canonical_url . "\n" .

            $timestamp . "\n" .

            $nonce . "\n" .

            $body . "\n";

        $private_key = $this->getPrivateKey($sslKeyPath);

        openssl_sign($message, $raw_sign, $private_key, 'sha256WithRSAEncryption');

        $sign   = base64_encode($raw_sign);

        $token = sprintf('WECHATPAY2-SHA256-RSA2048 mchid="%s",nonce_str="%s",timestamp="%s",serial_no="%s",signature="%s"', $this->mchid, $nonce, $timestamp, $this->serial_no, $sign);

        return $token;

    }

    /**

     * 生成随机32位字符串

     * @param $length

     * @return string

     */

    public function createNonceStr($length = 16) { //生成随机16个字符的字符串

        $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

        $str = "";

        for ($i = 0; $i < $length; $i++) {

            $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);

        }

        return $str;

    }

    /**

     * 获取私钥

     * @param $filepath

     * @return false|resource

     */

    private function getPrivateKey($filepath = '')

    {

        if (empty($filepath)) {

            //私钥位置

            $cert_dir = ROOT_PATH.DS."config".DS."payment_cert".DS."wechatpay".DS;

            $filepath = $cert_dir."apiclient_key.pem";

        }

        return openssl_get_privatekey(file_get_contents($filepath));

    }

}