微信v3支付签名php代码

以下是微信v3支付签名的PHP代码示例：

<?php

function generateSign($method, $url, $timestamp, $nonceStr, $body) {
    $merchantId = "YOUR_MERCHANT_ID"; // 商户号
    $serialNo = "YOUR_SERIAL_NO"; // 商户API证书序列号
    $privateKey = file_get_contents("path/to/your/private/key.pem"); // 商户API私钥

    $message = $method . "\n" .
        $url . "\n" .
        $timestamp . "\n" .
        $nonceStr . "\n" .
        $body . "\n";

    $signature = "";
    openssl_sign($message, $signature, $privateKey, "sha256WithRSAEncryption");

    $signature = base64_encode($signature);

    return "WECHATPAY2-SHA256-RSA2048 " .
        "mchid=\"" . $merchantId . "\", " .
        "serial_no=\"" . $serialNo . "\", " .
        "timestamp=\"" . $timestamp . "\", " .
        "nonce_str=\"" . $nonceStr . "\", " .
        "signature=\"" . $signature . "\"";
}

// 使用示例
$method = "POST";
$url = "https://api.mch.weixin.qq.com/v3/pay/transactions/native";
$timestamp = time();
$nonceStr = "YOUR_NONCE_STR";
$body = '{"mchid":"YOUR_MERCHANT_ID","out_trade_no":"YOUR_OUT_TRADE_NO","appid":"YOUR_APPID","description":"YOUR_DESCRIPTION","notify_url":"YOUR_NOTIFY_URL","amount":{"total":100,"currency":"CNY"}}';

$sign = generateSign($method, $url, $timestamp, $nonceStr, $body);

echo $sign;

?>

在代码中，需要填写自己的商户号、证书序列号、私钥以及请求的URL、请求体等信息。使用时，只需要调用 `generateSign` 函数即可生成签名字符串。