微信支付-商家转账到零钱(企业付款到零钱升级),微信接口可以获取证书序列号，但是没有16进制格式的证书序列号号，接口返回的是10进制格式，但是php不支持大数10进制转16进制。

1.可以引入其他库解决，如 GMP 扩展。

2.可以直接配置到小程序后台，用到时直接从数据库获取。

3.直接使用微信官方库https://github.com/wechatpay-apiv3/wechatpay-php

这里采用方式2，见下方代码

/**
	 * 商家转账到零钱
	 * @param $batch_name
	 * @param $out_trade_no
	 * @param $money
	 * @param $openid
	 * @throws WxPayException
	 */
	public static function transfer($batch_name, $out_trade_no, $money, $openid)
	{
		$url = 'https://api.mch.weixin.qq.com/v3/transfer/batches';
		$wepro_appid = D('Home/Front')->get_config_by_name('wepro_appid');


		$pars = [];
		$pars['appid'] = $wepro_appid; //直连商户的appid
		$pars['out_batch_no'] = 'batch' . $out_trade_no; //商户系统内部的商家批次单号，要求此参数只能由数字、大小写字母组成，在商户系统内部唯一
		$pars['batch_name'] = $batch_name; //该笔批量转账的名称
		$pars['batch_remark'] = $batch_name; //转账说明，UTF8编码，最多允许32个字符
		//$pars['total_amount'] = intval($money * 100); //转账总金额 单位为“分”
		$pars['total_amount'] = $money;
		$pars['total_num'] = 1; //转账总笔数
		$pars['transfer_detail_list'][0] = [
			'out_detail_no' => 'transfer' . $out_trade_no,
			'transfer_amount' => $pars['total_amount'],
			'transfer_remark' => $batch_name,
			'openid' => $openid
		]; //转账明细列表
		$token = self::getToken($pars); //获取token

		$res = self::https_request($url, json_encode($pars), $token); //发送请求
		$data = json_decode($res, true);
		
		if (isset($data['batch_id']) && $data['batch_id']) {
			$info = array(
				'code'=>1,
				'batch_id'=>$data['batch_id']
			);
			
		}else{
			$info = array(
				'code'=>'FAIL',
				'err_code_des'=>$data['message']
			);
		}
		return $info;
	}

	public static	function https_request($url, $data = null, $token)
	{
		$curl = curl_init();
		curl_setopt($curl, CURLOPT_URL, (string)$url);
		curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
		curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);
		if (!empty($data)) {
			curl_setopt($curl, CURLOPT_POST, 1);
			curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
		}
		curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
		//添加请求头
		$headers = [
			'Authorization:WECHATPAY2-SHA256-RSA2048 ' . $token,
			'Accept: application/json',
			'Content-Type: application/json; charset=utf-8',
			'User-Agent:Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36',
		];
		if (!empty($headers)) {
			curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
		}
		$output = curl_exec($curl);
		curl_close($curl);
		return $output;
	}

	public static function getToken($pars)
	{
		// $url = 'https://api.mch.weixin.qq.com/v3/certificates';
		$url = 'https://api.mch.weixin.qq.com/v3/transfer/batches';
		$http_method = 'POST'; //请求方法（GET,POST,PUT）
		$timestamp = time(); //请求时间戳
		$url_parts = parse_url($url); //获取请求的绝对URL
		$nonce = $timestamp . rand('10000', '99999'); //请求随机串
		$body = json_encode((object)$pars); //请求报文主体




		$mchid = D('Home/Front')->get_config_by_name('wepro_partnerid');
		$serialNumberHex = D('Home/Front')->get_config_by_name('wechat_rootca_pem');

		$stream_opts = [
			"ssl" => [
				"verify_peer" => false,
				"verify_peer_name" => false,
			]
		];
		try {
			$certPem = self::getCertPem();
			$apiclient_cert_path = $certPem['certPem'];
			$apiclient_key_path = $certPem['keyPem'];
			//$apiclient_cert_arr = openssl_x509_parse(file_get_contents($apiclient_cert_path, false, stream_context_create($stream_opts)));

			
			$serial_no = $serialNumberHex;  // 证书序列号  
		
			$mch_private_key = file_get_contents($apiclient_key_path, false, stream_context_create($stream_opts)); //密钥
			$merchant_id = $mchid;
			$canonical_url = ($url_parts['path'] . (!empty($url_parts['query']) ? "?${url_parts['query']}" : ""));
			$message = $http_method . "\n" .
				$canonical_url . "\n" .
				$timestamp . "\n" .
				$nonce . "\n" .
				$body . "\n";
			openssl_sign($message, $raw_sign, $mch_private_key, 'sha256WithRSAEncryption');
			$sign = base64_encode($raw_sign); //签名
			$schema = 'WECHATPAY2-SHA256-RSA2048';
			$token = sprintf(
				'mchid="%s",nonce_str="%s",timestamp="%d",serial_no="%s",signature="%s"',
				$merchant_id,
				$nonce,
				$timestamp,
				$serial_no,
				$sign
			); //微信返回token
		} catch (WxPayException $e) {
			$msg = $e->errorMessage();
			throw new WxPayException("curl出错，错误码:" . $msg);
		}

		return $token;
	}

	/**
	 * 获取cert证书文件
	 * @return array
	 * @throws WxPayException
	 */
	private  static function getCertPem()
	{

		// cert目录


		$path = ROOT_PATH . '/Data/wxpaylogs/';

		$wechat_apiclient_cert_pem = D('Home/Front')->get_config_by_name('wechat_apiclient_cert_pem');
		$wechat_apiclient_key_pem = D('Home/Front')->get_config_by_name('wechat_apiclient_key_pem');

		if (empty($wechat_apiclient_cert_pem) || empty($wechat_apiclient_key_pem)) {
			throw new WxPayException("请先到后台小程序设置填写微信支付证书文件");
		}

		$file_cert_name = mt_rand(1, 99) . '_cert.pem';
		$file_key_name = mt_rand(100, 999) . '_key.pem';

		file_put_contents($path . $file_cert_name, $wechat_apiclient_cert_pem);
		file_put_contents($path . $file_key_name, $wechat_apiclient_key_pem);

		return [
			'certPem' => $path . $file_cert_name,
			'keyPem' => $path . $file_key_name
		];
	}