不知不觉微信支付也更新了，接口版本也升级到了V3,
跟着微信的升级，将个人使用微信支付类也进行了升级，
V3微信支付文档：https://pay.weixin.qq.com/wiki/doc/apiv3/index.shtml
（相关方法已经过测试，不保证完全没问题，仅供参考，如测试有问题，可联系作者修改----查看原文）

使用方法还和之前的一样（V2微信支付），直接传递参数就可使用：

新版新增了composer安装，便于集成框架使用（Github地址）：

composer require fengkui/pay

首先把配置文件填写完整（细心不要填错，否则会导致签名错误）：

# 微信支付配置
$wechatConfig = [
    'xcxid'         => '', // 小程序 appid
    'appid'         => '', // 微信支付 appid
    'mchid'         => '', // 微信支付 mch_id 商户收款账号
    'key'           => '', // 微信支付 apiV3key（尽量包含大小写字母，否则验签不通过）
    'appsecret'     => '', // 公众帐号 secert (公众号支付获取 code 和 openid 使用)

    'notify_url'    => '', // 接收支付状态的连接  改成自己的回调地址
    'redirect_url'  => '', // 公众号支付，调起支付页面

    'serial_no'     => '', // 证书序列号
    'cert_client'   => './cert/apiclient_cert.pem', // 证书（退款，红包时使用）
    'cert_key'      => './cert/apiclient_key.pem', // 商户私钥（Api安全中下载）
    'public_key'    => './cert/public_key.pem', // 平台公钥（调动证书列表，自动生成，注意目录读写权限）
];

支付类封装相关方法：

使用方法（这里已小程序支付为示例）：

<?php
require_once('./vendor/autoload.php');

$config = []; // 支付配置
$order = [
    'order_sn' => time(), // 订单编号
    'total_amount' => 1, // 订单金额（分）
    'body' => '测试商品', // 商品名称
    'openid' => '', // 用户openid
    // 'type' => 'Wap',
];

$wechat = new fengkui\Pay\Wechat($config);
$re = $wechat->xcx($order);
die(json_encode($re)); // JSON化直接返回小程序客户端

如下代码是封装好的完整支付类文件（Wechat.php），
可以根据自己需求随意修改，详细的使用方法后期会有文档：

<?php
/**
 * @Author: [FENG] <1161634940@qq.com>
 * @Date:   2019-09-06 09:50:30
 * @Last Modified by:   [FENG] <1161634940@qq.com>
 * @Last Modified time: 2021-07-12 18:24:18
 */
namespace fengkui\Pay;

use Exception;
use RuntimeException;
use fengkui\Supports\Http;

/**
 * Wechat 微信支付
 * 新版（V3）接口（更新中）
 */
class Wechat
{
    const AUTH_TAG_LENGTH_BYTE = 16;

    // 新版相关接口
    // GET 获取平台证书列表
    private static $certificatesUrl = 'https://api.mch.weixin.qq.com/v3/certificates';
    // 统一下订单管理
    private static $transactionsUrl = 'https://api.mch.weixin.qq.com/v3/pay/transactions/';
    // 申请退款
    private static $refundUrl = 'https://api.mch.weixin.qq.com/v3/refund/domestic/refunds';
    // 静默授权，获取code
    private static $authorizeUrl = 'https://open.weixin.qq.com/connect/oauth2/authorize';
    // 通过code获取access_token以及openid
    private static $accessTokenUrl = 'https://api.weixin.qq.com/sns/oauth2/access_token';

    // 支付完整配置
    private static $config = array(
        'xcxid'         => '', // 小程序 appid
        'appid'         => '', // 微信支付 appid
        'mchid'         => '', // 微信支付 mch_id 商户收款账号
        'key'           => '', // 微信支付 apiV3key（尽量包含大小写字母，否则验签不通过）
        'appsecret'     => '', // 公众帐号 secert (公众号支付获取 code 和 openid 使用)

        'notify_url'    => '', // 接收支付状态的连接  改成自己的回调地址
        'redirect_url'  => '', // 公众号支付，调起支付页面

        'serial_no'     => '', // 证书序列号
        'cert_client'   => './cert/apiclient_cert.pem', // 证书（退款，红包时使用）
        'cert_key'      => './cert/apiclient_key.pem', // 商户私钥（Api安全中下载）
        'public_key'    => './cert/public_key.pem', // 平台公钥（调动证书列表，自动生成，注意目录读写权限）
    );

    /**
     * [__construct 构造函数]
     * @param [type] $config [传递微信支付相关配置]
     */
    public function __construct($config=NULL, $referer=NULL){
        $config && self::$config = array_merge(self::$config, $config);
    }

    /**
     * [unifiedOrder 统一下单]
     * @param  [type]  $order [订单信息（必须包含支付所需要的参数）]
     * @param  boolean $type  [区分是否是小程序，是则传 true]
     * @return [type]         [description]
     * $order = array(
     *      'body'         => '', // 产品描述
     *      'order_sn'     => '', // 订单编号
     *      'total_amount' => '', // 订单金额（分）
     * );
     */
    public static function unifiedOrder($order, $type=false)
    {
        $config = array_filter(self::$config);

        // 获取配置项
        $params = array(
            'appid'         => $type ? $config['xcxid'] : $config['appid'], // 由微信生成的应用ID
            'mchid'         => $config['mchid'], // 直连商户的商户号
            'description'   => $order['body'], // 商品描述
            'out_trade_no'  => (string)$order['order_sn'], // 商户系统内部订单号
            'notify_url'    => $config['notify_url'], // 通知URL必须为直接可访问的URL
            'amount'        => ['total' => (int)$order['total_amount'], 'currency' => 'CNY'], // 订单金额信息
        );

        !empty($order['attach']) && $params['attach'] = $order['attach']; // 附加数据
        if (!empty($order['time_expire'])) { // 订单失效时间
            preg_match('/[年\/-]/', $order['time_expire']) && $order['time_expire'] = strtotime($order['time_expire']);
            $time = $order['time_expire'] > time() ? $order['time_expire'] : $order['time_expire'] + time();
            $params['time_expire'] = date(DATE_ATOM, $time);
        }

        if (!in_array($order['type'], ['native'])) {
            !empty($order['openid']) && $params['payer'] = ['openid' => $order['openid']];
            $params['scene_info'] = ['payer_client_ip' => self::get_ip()];
        }

        if (in_array($order['type'], ['iOS', 'Android', 'Wap'])) {
            $params['scene_info']['h5_info'] = ['type' => $order['type']];
            $url = self::$transactionsUrl . 'h5'; // 拼接请求地址
        } else {
            $url = self::$transactionsUrl . strtolower($order['type']); // 拼接请求地址
        }

        $header = self::createAuthorization($url, $params, 'POST');
        $response = Http::post($url, json_encode($params, JSON_UNESCAPED_UNICODE), $header);
        $result = json_decode($response, true);
        if (isset($result['code']) && isset($result['message'])) {
            throw new \Exception("[" . $result['code'] . "] " . $result['message']);
        }

        return $result;
    }

    /**
     * [query 查询订单]
     * @param  [type]  $orderSn [订单编号]
     * @param  boolean $type    [微信支付订单编号，是否是微信支付订单号]
     * @return [type]           [description]
     */
    public static function query($orderSn, $type = false)
    {
        $config = self::$config;
        $url = self::$transactionsUrl . ($type ? 'id/' : 'out-trade-no/') . $orderSn . '?mchid=' . $config['mchid'];
        $params = '';

        $header = self::createAuthorization($url, $params, 'GET');
        $response = Http::get($url, $params, $header);
        $result = json_decode($response, true);

        return $result;
    }

    /**
     * [close 关闭订单]
     * @param  [type] $orderSn [微信支付订单编号]
     * @return [type]          [description]
     */
    public static function close($orderSn)
    {
        $config = self::$config;
        $url = self::$transactionsUrl . 'out-trade-no/' . $orderSn . '/close';
        $params['mchid'] = $config['mchid'];

        $header = self::createAuthorization($url, $params, 'POST');
        $response = Http::post($url, json_encode($params, JSON_UNESCAPED_UNICODE), $header);
        $result = json_decode($response, true);

        return true;
    }

    /**
     * [js 获取jssdk需要用到的数据]
     * @param  [type] $order [订单信息数组]
     * @return [type]        [description]
     */
    public static function js($order=[]){
        $config = self::$config;
        if (!is_array($order) || count($order) < 3)
            die("订单数组信息缺失！");
        if (count($order) == 4 && !empty($order['openid'])) {
            $data = self::xcx($order, false, false); // 获取支付相关信息(获取非小程序信息)
            return $data;
        }
        $code = !empty($order['code']) ? $order['code'] : ($_GET['code'] ?? '');
        $redirectUri = $_SERVER['REQUEST_SCHEME'] . '://' . $_SERVER['HTTP_HOST'] . rtrim($_SERVER['REQUEST_URI'], '/') . '/'; // 重定向地址

        $params = ['appid' => $config['appid']];
        // 如果没有get参数没有code；则重定向去获取code；
        if (empty($code)) {
            $params['redirect_uri'] = $redirectUri; // 返回的url
            $params['response_type'] = 'code';
            $params['scope'] = 'snsapi_base';
            $params['state'] = $order['order_sn']; // 获取订单号

            $url = self::$authorizeUrl . '?'. http_build_query($params) .'#wechat_redirect';
        } else {
            $params['secret'] = $config['appsecret'];
            $params['code'] = $code;
            $params['grant_type'] = 'authorization_code';

            $response = Http::get(self::$accessTokenUrl, $params); // 进行GET请求
            $result = json_decode($response, true);

            $order['openid'] = $result['openid']; // 获取到的openid
            $data = self::xcx($order, false, false); // 获取支付相关信息(获取非小程序信息)

            if (!empty($order['code'])) {
                return $data;
            }

            $url = $config['redirect_url'] ?? $redirectUri;
            $url .= '?data=' . json_encode($data, JSON_UNESCAPED_UNICODE);
        }
        header('Location: '. $url);
        die;
    }

    /**
     * [app 获取APP支付需要用到的数据]
     * @param  [type]  $order [订单信息数组]
     * @return [type]         [description]
     */
    public static function app($order=[], $log=false)
    {
        if(empty($order['order_sn']) || empty($order['total_amount']) || empty($order['body'])){
            die("订单数组信息缺失！");
        }

        $order['type'] = 'app'; // 获取订单类型，用户拼接请求地址
        $result = self::unifiedOrder($order, true);
        if (!empty($result['prepay_id'])) {
            $data = array (
                'appId'     => self::$config['appid'], // 微信开放平台审核通过的移动应用appid
                'timeStamp' => (string)time(),
                'nonceStr'  => self::get_rand_str(32, 0, 1), // 随机32位字符串
                'prepayid'  => $result['prepay_id'],
            );
            $data['paySign'] = self::makeSign($data);
            $data['partnerid'] = $config['mchid'];
            $data['package'] = 'Sign=WXPay';
            return $data; // 数据小程序客户端
        } else {
            return $log ? $result : false;
        }
    }

    /**
     * [h5 微信H5支付]
     * @param  [type] $order [订单信息数组]
     * @return [type]        [description]
     */
    public static function h5($order=[], $log=false)
    {
        if(empty($order['order_sn']) || empty($order['total_amount']) || empty($order['body']) || empty($order['type']) || !in_array(strtolower($order['type']), ['ios', 'android', 'wap'])){
            die("订单数组信息缺失！");
        }
        $result = self::unifiedOrder($order);
        if (!empty($result['h5_url'])) {
            return $result['h5_url']; // 返回链接让用户点击跳转
        } else {
            return $log ? $result : false;
        }
    }

    /**
     * [xcx 获取jssdk需要用到的数据]
     * @param  [type]  $order [订单信息数组]
     * @param  boolean $log   [description]
     * @param  boolean $type  [区分是否是小程序，默认 true]
     * @return [type]         [description]
     */
    public static function xcx($order=[], $log=false, $type=true)
    {
        if(empty($order['order_sn']) || empty($order['total_amount']) || empty($order['body']) || empty($order['openid'])){
            die("订单数组信息缺失！");
        }

        $order['type'] = 'jsapi'; // 获取订单类型，用户拼接请求地址
        $config = self::$config;
        $result = self::unifiedOrder($order, $type);
        if (!empty($result['prepay_id'])) {
            $data = array (
                'appId'     => $type ? $config['xcxid'] : $config['appid'], // 由微信生成的应用ID
                'timeStamp' => (string)time(),
                'nonceStr'  => self::get_rand_str(32, 0, 1), // 随机32位字符串
                'package'   => 'prepay_id='.$result['prepay_id'],
            );
            $data['paySign'] = self::makeSign($data);
            $data['signType'] = 'RSA';
            return $data; // 数据小程序客户端
        } else {
            return $log ? $result : false;
        }
    }

    /**
     * [scan 微信扫码支付]
     * @param  [type] $order [订单信息数组]
     * @return [type]        [description]
     */
    public static function scan($order=[], $log=false)
    {
        if(empty($order['order_sn']) || empty($order['total_amount']) || empty($order['body'])){
            die("订单数组信息缺失！");
        }
        $order['type'] = 'native'; // Native支付
        $result = self::unifiedOrder($order);

        if (!empty($result['code_url'])) {
            return urldecode($result['code_url']); // 返回链接让用户点击跳转
        } else {
            return $log ? $result : false;
        }
    }

    /**
     * [notify 回调验证]
     * @return [array] [返回数组格式的notify数据]
     */
    public static function notify($server = [], $response = [])
    {
        $config = self::$config;
        $server = $server ?? $_SERVER;
        $response = $response ?: file_get_contents('php://input', 'r');
        if (empty($response) || empty($server['HTTP_WECHATPAY_SIGNATURE'])) {
            return false;
        }
        $body = [
            'timestamp' => $server['HTTP_WECHATPAY_TIMESTAMP'],
            'nonce' => $server['HTTP_WECHATPAY_NONCE'],
            'data' => $response,
        ];
        // 验证应答签名
        $verifySign = self::verifySign($body, trim($server['HTTP_WECHATPAY_SIGNATURE']), trim($server['HTTP_WECHATPAY_SERIAL']));
        if (!$verifySign) {
            die("签名验证失败！");
        }
        $result = json_decode($response, true);
        if (empty($result) || $result['event_type'] != 'TRANSACTION.SUCCESS' || $result['summary'] != '支付成功') {
            return false;
        }
        // 加密信息
        $associatedData = $result['resource']['associated_data'];
        $nonceStr = $result['resource']['nonce'];
        $ciphertext = $result['resource']['ciphertext'];
        $data = $result['resource']['ciphertext'] = self::decryptToString($associatedData, $nonceStr, $ciphertext);

        return json_decode($data, true);
    }

    /**
     * [refund 微信支付退款]
     * @param  [type] $order [订单信息]
     * @param  [type] $type  [是否是小程序]
     */
    public static function refund($order)
    {
        $config = self::$config;
        if(empty($order['refund_sn']) || empty($order['refund_amount']) || (empty($order['order_sn']) && empty($order['transaction_id']))){
            die("订单数组信息缺失！");
        }

        $params = array(
            'out_refund_no' => (string)$order['refund_sn'], // 商户退款单号
            'funds_account' => 'AVAILABLE', // 退款资金来源
            'amount' => [
                    'refund' => $order['refund_amount'],
                    'currency' => 'CNY',
                ]
        );

        if (!empty($order['transaction_id'])) {
            $params['transaction_id'] = $order['transaction_id'];
            $orderDetail = self::query($order['transaction_id'], true);
        } else {
            $params['out_trade_no'] = $order['order_sn'];
            $orderDetail = self::query($order['order_sn']);
        }
        $params['amount']['total'] = $orderDetail['amount']['total'];
        !empty($order['reason']) && $params['reason'] = $order['reason'];

        $url = self::$refundUrl;
        $header = self::createAuthorization($url, $params, 'POST');
        $response = Http::post($url, json_encode($params, JSON_UNESCAPED_UNICODE), $header);
        $result = json_decode($response, true);

        return $result;
    }

    /**
     * [queryRefund 查询退款]
     * @param  [type] $refundSn [退款单号]
     * @return [type]           [description]
     */
    public static function queryRefund($refundSn, $type = false)
    {
        $url = self::$refundUrl . '/' . $refundSn;
        $params = '';

        $header = self::createAuthorization($url, $params, 'GET');
        $response = Http::get($url, $params, $header);
        $result = json_decode($response, true);

        return $result;
    }

    /**
     * [success 通知支付状态]
     */
    public static function success()
    {
        $str = ['code'=>'SUCCESS', 'message'=>'成功'];
        die(json_encode($str, JSON_UNESCAPED_UNICODE));
    }

    /**
     * [createAuthorization 获取接口授权header头信息]
     * @param  [type] $url    [请求地址]
     * @param  array  $data   [请求参数]
     * @param  string $method [请求方式]
     * @return [type]         [description]
     */
    //生成v3 Authorization
    protected static function createAuthorization($url, $data=[], $method='POST'){
        $config = self::$config;
        //商户号
        $mchid = $config['mchid'];
        // 证书序列号
        if (empty($config['serial_no'])) {
            $certFile = @file_get_contents($config['cert_client']);
            $certArr = openssl_x509_parse($publicStr);
            $serial_no = $certArr['serialNumberHex'];
        } else {
            $serial_no = $config['serial_no'];
        }

        // 解析url地址
        $url_parts = parse_url($url);
        //生成签名
        $body = [
            'method' => $method,
            'url'   => ($url_parts['path'] . (!empty($url_parts['query']) ? "?${url_parts['query']}" : "")),
            'time'  => time(), // 当前时间戳
            'nonce' => self::get_rand_str(32, 0, 1), // 随机32位字符串
            'data'  => (strtolower($method) == 'post' ? json_encode($data, JSON_UNESCAPED_UNICODE) : $data), // POST请求时 需要 转JSON字符串
        ];
        $sign = self::makeSign($body);
        //Authorization 类型
        $schema = 'WECHATPAY2-SHA256-RSA2048';
        //生成token
        $token = sprintf('mchid="%s",nonce_str="%s",timestamp="%d",serial_no="%s",signature="%s"', $mchid, $body['nonce'], $body['time'], $serial_no, $sign);

        $header = [
            'Content-Type:application/json',
            'Accept:application/json',
            'User-Agent:*/*',
            'Authorization: '.  $schema . ' ' . $token
        ];
        return $header;
    }

    /**
     * [makeSign 生成签名]
     * @param  [type] $data [加密数据]
     * @return [type]       [description]
     */
    public static function makeSign($data)
    {
        $config = self::$config;
        if (!in_array('sha256WithRSAEncryption', \openssl_get_md_methods(true))) {
            throw new \RuntimeException("当前PHP环境不支持SHA256withRSA");
        }
        // 拼接生成签名所需的字符串
        $message = '';
        foreach ($data as $value) {
            $message .= $value . "\n";
        }
        // 商户私钥
        $private_key = self::getPrivateKey($config['cert_key']);
        // 生成签名
        openssl_sign($message, $sign, $private_key, 'sha256WithRSAEncryption');
        $sign = base64_encode($sign);
        return $sign;
    }

    /**
     * [verifySign 验证签名]
     * @param  [type] $data   [description]
     * @param  [type] $sign   [description]
     * @param  [type] $serial [description]
     * @return [type]         [description]
     */
    public static function verifySign($data, $sign, $serial)
    {
        $config = self::$config;
        if (!in_array('sha256WithRSAEncryption', \openssl_get_md_methods(true))) {
            throw new \RuntimeException("当前PHP环境不支持SHA256withRSA");
        }
        $sign = \base64_decode($sign);
        // 拼接生成签名所需的字符串
        $message = '';
        foreach ($data as $value) {
            $message .= $value . "\n";
        }
        // 获取证书相关信息
        self::certificates($serial);
        // 平台公钥
        $public_key = self::getPublicKey($config['public_key']); //平台公钥
        // 验证签名
        $recode = \openssl_verify($message, $sign, $public_key, 'sha256WithRSAEncryption');
        return $recode == 1 ? true : false;
    }

    //获取私钥
    public static function getPrivateKey($filepath)
    {
        return openssl_pkey_get_private(file_get_contents($filepath));
    }

    //获取公钥
    public static function getPublicKey($filepath)
    {
        return openssl_pkey_get_public(file_get_contents($filepath));
    }

    /**
     * [certificates 获取证书]
     * @return [type] [description]
     */
    public static function certificates($serial)
    {
        $config = self::$config;

        $publicStr = @file_get_contents($config['public_key']);
        if ($publicStr) { // 判断证书是否存在
            $openssl = openssl_x509_parse($publicStr);
            if ($openssl['serialNumberHex'] == $serial) { // 是否是所需证书
                // return self::getPublicKey($config['public_key']); //平台公钥
                return '';
            }
        }

        $url = self::$certificatesUrl;
        $params = '';

        $header = self::createAuthorization($url, $params, 'GET');
        $response = Http::get($url, $params, $header);
        $result = json_decode($response, true);
        if (empty($result['data'])) {
            throw new RuntimeException("[" . $result['code'] . "] " . $result['message']);
        }
        foreach ($result['data'] as $key => $certificate) {
            if ($certificate['serial_no'] == $serial) {
                $publicKey = self::decryptToString(
                    $certificate['encrypt_certificate']['associated_data'],
                    $certificate['encrypt_certificate']['nonce'],
                    $certificate['encrypt_certificate']['ciphertext']
                );
                file_put_contents($config['public_key'], $publicKey);
                break; // 终止循环
            }
            // self::$publicKey[$certificate['serial_no']] = $publicKey;
        }
        // return self::getPublicKey($config['public_key']); //平台公钥
    }

    /**
     * [decryptToString 证书和回调报文解密]
     * @param  [type] $associatedData [附加数据包（可能为空）]
     * @param  [type] $nonceStr       [加密使用的随机串初始化向量]
     * @param  [type] $ciphertext     [Base64编码后的密文]
     * @return [type]                 [description]
     */
    public static function decryptToString($associatedData, $nonceStr, $ciphertext)
    {
        $config = self::$config;
        $ciphertext = base64_decode($ciphertext);
        if (strlen($ciphertext) <= self::AUTH_TAG_LENGTH_BYTE) {
            return false;
        }

        // ext-sodium (default installed on >= PHP 7.2)
        if (function_exists('\sodium_crypto_aead_aes256gcm_is_available') &&
            \sodium_crypto_aead_aes256gcm_is_available()) {
            return \sodium_crypto_aead_aes256gcm_decrypt($ciphertext, $associatedData, $nonceStr, $config['key']);
        }

        // ext-libsodium (need install libsodium-php 1.x via pecl)
        if (function_exists('\Sodium\crypto_aead_aes256gcm_is_available') &&
            \Sodium\crypto_aead_aes256gcm_is_available()) {
            return \Sodium\crypto_aead_aes256gcm_decrypt($ciphertext, $associatedData, $nonceStr, $config['key']);
        }

        // openssl (PHP >= 7.1 support AEAD)
        if (PHP_VERSION_ID >= 70100 && in_array('aes-256-gcm', \openssl_get_cipher_methods())) {
            $ctext = substr($ciphertext, 0, -self::AUTH_TAG_LENGTH_BYTE);
            $authTag = substr($ciphertext, -self::AUTH_TAG_LENGTH_BYTE);

            return \openssl_decrypt($ctext, 'aes-256-gcm', $config['key'], \OPENSSL_RAW_DATA, $nonceStr,
                $authTag, $associatedData);
        }

        throw new \RuntimeException('AEAD_AES_256_GCM需要PHP 7.1以上或者安装libsodium-php');
    }

    /** fengkui.net
     * [get_rand_str 获取随机字符串]
     * @param  integer $randLength    [长度]
     * @param  integer $addtime       [是否加入当前时间戳]
     * @param  integer $includenumber [是否包含数字]
     * @return [type]                 [description]
     */
    public static function get_rand_str($randLength=6, $addtime=0, $includenumber=1)
    {
        if ($includenumber)
            $chars='abcdefghijklmnopqrstuvwxyzABCDEFGHJKLMNPQEST123456789';
        $chars='abcdefghijklmnopqrstuvwxyz';

        $len = strlen($chars);
        $randStr = '';
        for ($i=0; $i<$randLength; $i++){
            $randStr .= $chars[rand(0, $len-1)];
        }
        $tokenvalue = $randStr;
        $addtime && $tokenvalue = $randStr . time();
        return $tokenvalue;
    }

    /** fengkui.net
     * [get_ip 定义一个函数get_ip() 客户端IP]
     * @return [type] [description]
     */
    public static function get_ip()
    {
        if (getenv("HTTP_CLIENT_IP"))
            $ip = getenv("HTTP_CLIENT_IP");
        else if(getenv("HTTP_X_FORWARDED_FOR"))
            $ip = getenv("HTTP_X_FORWARDED_FOR");
        else if(getenv("REMOTE_ADDR"))
            $ip = getenv("REMOTE_ADDR");
        else $ip = "Unknow";

        if(preg_match('/^((?:(?:25[0-5]|2[0-4]\d|((1\d{2})|([1-9]?\d)))\.){3}(?:25[0-5]|2[0-4]\d|((1\d{2})|([1 -9]?\d))))$/', $ip))
            return $ip;
        else
            return '';
    }
}

本文参考文档：
1、微信支付 小程序 （v3）- PHP 完整后端代码
2、PHP 微信小程序 微信支付 v3
3、微信支付V3版本小程序支付 php签名,验签,数据解密代码分享（完整方法主参考）
4、微信支付 API v3 回调通知 签名验证 PHPdemo有嘛？