php 微信公众号支付

首先需要申请微信公众号支付，配置授权域名及授权目录。以下是可运行的代码:

前台 ajax 调用支付数据：

<div class="apply" onclick="callBack()">微信支付</div>

function onBridgeReady(){
    var amount = $('#amount').val();
    $.post(url,data,function(result){
        result = JSON.parse(result);
        if(result.code == 0) {
            WeixinJSBridge.invoke(
                'getBrandWCPayRequest',
                result.data,
                function(res){  
                    if(res.err_msg == "get_brand_wcpay_request:ok" ) {window.location.href = "成功支付跳转url"}     // 使用以上方式判断前端返回,微信团队郑重提示：res.err_msg将在用户支付成功后返回    ok，但并不保证它绝对可靠。 
                }); 
        } else {
            alert(result.msg);
            return;
        }
    })
}

function callBack() {
    if (typeof WeixinJSBridge == "undefined"){
        if( document.addEventListener ){
            document.addEventListener('WeixinJSBridgeReady', onBridgeReady, false);
        }else if (document.attachEvent){
            document.attachEvent('WeixinJSBridgeReady', onBridgeReady); 
            document.attachEvent('onWeixinJSBridgeReady', onBridgeReady);
        }
    }else{
        onBridgeReady();
    } 
}

后台返回支付数据, 引入 pay 类文件(在最后)：

$Pay = new Pay($config);
$order = [
    "body"=>"支付0.01元",
    "out_trade_no"=>"123456", #商户支付单号
    "total_fee"=>"0.01",
    "openid"=>openid
];

$pay_params = $Pay->wxPayOrder($order);

if($pay_params) {

    $data["code"] = 0;
    $data["msg"] = "成功";
    $data["data"]["appId"] = $pay_params["appId"];
    $data["data"]["timeStamp"] = $pay_params["timeStamp"];
    $data["data"]["nonceStr"] = $pay_params["nonceStr"];
    $data["data"]["signType"] = 'MD5';
    $data["data"]["package"] = $pay_params["package"];
    $data["data"]["paySign"] = $pay_params["sign"];

    echo json_encode($data);exit;
}

pay 类文件(抽离通用方法做扩展文件)：

class Pay
{
    //应用ID
    protected $appId;
    //商户号
    protected $mch_id;
    //商户秘钥
    protected $mch_key;
    //通知地址
    protected $notify_url;
    //证书路径
    protected $apiclient_cert_path;
    //证书路径
    protected $apiclient_key_path;

    #微信公众号支付
    public function wxPayOrder($order)
    {
        $prepayid = $this->wxunifiedorder($order);
        if ($prepayid !== false) {
            return $this->wxcallPayParams($prepayid);
        } else {
            return [];
        }
    }

    #微信公众号统一下单
    public function wxunifiedorder($order)
    {
        $url = "https://api.mch.weixin.qq.com/pay/unifiedorder";
        $requestData = [
            "appid" => $this->appId,
            "mch_id" => $this->mch_id,
            "nonce_str" => getRandom("32", "0123456789"),
            "sign" => "",
            "body" => $order["body"],
            "out_trade_no" => $order["out_trade_no"],
            "total_fee" => $order["total_fee"] * 100,
            "spbill_create_ip" => getClientIP(),//获取ip
            "notify_url" => $this->notify_url,
            "trade_type" => "JSAPI",
            "openid" => $order["openid"]
        ];
        $requestData["sign"] = $this->sign($requestData);
        $postStr = $this->http_curl($url, "post", $this->array2xml($requestData));
        try {
            if ($postStr) {
                $rs = (array)simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
                if ($rs["return_code"] == "SUCCESS") {
                    if ($rs["result_code"] == "SUCCESS") {
                        return $rs["prepay_id"];
                    } else {
                        throw new \Exception($rs["err_code_des"]);
                    }
                } else {
                    throw new \Exception($rs["return_msg"]);
                }
            } else {
                throw new \Exception("统一下单调用失败");
            }
        } catch (\Exception $e) {
            $this->error = $e->getMessage();
            return false;
        }
    }

    #公众号调起支付接口参数
    public function wxcallPayParams($prepayid)
    {
        $requestData = [
            "appId" => $this->appId,
            "package" => "prepay_id=".$prepayid,
            "nonceStr" => getRandom(32, "0123456789"),#获取32位随机数字
            "timeStamp" => (string)time(),
            "signType" => "MD5"
        ];
        $requestData["sign"] = $this->sign($requestData);
        return $requestData;
    }

    //签名
    public function sign($data)
    {
        $params = array();
        foreach ($data as $k => $v) {
            if (!empty($data[$k]) && $k != "sign") {
                $params[$k] = $v;
            }
        }
        ksort($params);
        $stringSignTemp = "";
        $i = 0;
        foreach ($params as $k => $v) {
            if ($i == 0) {
                $stringSignTemp .= $k . "=" . $v;
            } else {
                $stringSignTemp .= "&" . $k . "=" . $v;
            }
            $i++;
        }
        $stringSignTemp .= "&key=" . $this->mch_key;
        $sign = strtoupper(md5($stringSignTemp));
        return $sign;
    }

    //验证签名
    public function validateSign($data){
        $sign = $data["sign"];
        if($sign==$this->sign($data)){
            return true;
        }else{
            return false;
        }
    }

    private function http_curl($url, $type = "get", $data = "")
    {
        $ch = curl_init(); //初始化curl
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_HEADER, 0); //是否获取response header
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); //要求结果为字符串且输出到屏幕上
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); //不验证证书下同
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false); // 
        if (strtolower($type) == "post") {
            curl_setopt($ch, CURLOPT_POST, 1); //post提交方式
            curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
        }
        $rs = curl_exec($ch); //运行curl
        curl_close($ch);
        return $rs;
    }

    private function http_curl_ssl($url, $type = "get", $data = "")
    {
        $ch = curl_init(); //初始化curl
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_HEADER, 0); //是否获取response header
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); //要求结果为字符串且输出到屏幕上
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); //不验证证书下同
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2); //
        curl_setopt($ch,CURLOPT_SSLCERTTYPE,'PEM');
        curl_setopt($ch,CURLOPT_SSLCERT, $this->apiclient_cert_path);
        curl_setopt($ch,CURLOPT_SSLKEYTYPE,'PEM');
        curl_setopt($ch,CURLOPT_SSLKEY, $this->apiclient_key_path);

        if (strtolower($type) == "post") {
            curl_setopt($ch, CURLOPT_POST, 1); //post提交方式
            curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
        }

        $rs = curl_exec($ch); //运行curl
        Log::record("支付日志".var_export($rs,true));
        curl_close($ch);
        return $rs;
    }

    public function getError()
    {
        return $this->error;
    }

    public function array2xml($data){
         $xml = "<xml>";
         foreach($data as $k=>$v){
             $xml .= "<$k>".$v."</$k>";
         }
        $xml .= "</xml>";
         return $xml;
    }
}