appid = $appid;        $this->openid = $openid;        $this->mch_id = $mch_id;        $this->key = $key;        $this->out_trade_no = $out_trade_no;        $this->body = $body;        $this->total_fee = $total_fee;    }    public function pay()    {        //统一下单接口        $return = $this->weixinapp();        return $return;    }    //统一下单接口    private function unifiedorder()    {        $url = 'https://api.mch.weixin.qq.com/pay/unifiedorder';        $parameters = array(            'appid' => $this->appid, //小程序ID            'mch_id' => $this->mch_id, //商户号            'nonce_str' => $this->createNoncestr(), //随机字符串//            'body' => 'test', //商品描述            'body' => $this->body,//            'out_trade_no' => '2018013106125348', //商户订单号            'out_trade_no' => $this->out_trade_no,//            'total_fee' => floatval(0.01 * 100), //总金额 单位 分            'total_fee' => $this->total_fee,            'spbill_create_ip' => $_SERVER['REMOTE_ADDR'], //终端IP            // 'spbill_create_ip' => '192.168.0.161', //终端IP            'notify_url' => 'https://mobile.boyuan.com/api/a/payNotify.php', //通知地址  确保外网能正常访问            'openid' => $this->openid, //用户id            'trade_type' => 'JSAPI'//交易类型        );        //统一下单签名        $parameters['sign'] = $this->getSign($parameters);        $xmlData = $this->arrayToXml($parameters);        $return = $this->xmlToArray($this->postXmlCurl($xmlData, $url, 60));        return $return;    }    private static function postXmlCurl($xml, $url, $second = 30)    {        $ch = curl_init();        //设置超时        curl_setopt($ch, CURLOPT_TIMEOUT, $second);        curl_setopt($ch, CURLOPT_URL, $url);        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE); //严格校验        //设置header        curl_setopt($ch, CURLOPT_HEADER, FALSE);        //要求结果为字符串且输出到屏幕上        curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);        //post提交方式        curl_setopt($ch, CURLOPT_POST, TRUE);        curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 20);        curl_setopt($ch, CURLOPT_TIMEOUT, 40);        set_time_limit(0);        //运行curl        $data = curl_exec($ch);        //返回结果        if ($data) {            curl_close($ch);            return $data;        } else {            $error = curl_errno($ch);            curl_close($ch);            throw new WxPayException("curl出错，错误码:$error");        }    }    //数组转换成xml    private function arrayToXml($arr)    {        $xml = "
     
      ";        foreach ($arr as $key => $val) {            if (is_array($val)) {                $xml .= "<" . $key . ">" . arrayToXml($val) . "
      ";            } else {                $xml .= "<" . $key . ">" . $val . "
      ";            }        }        $xml .= "
     ";        return $xml;    }    //xml转换成数组    private function xmlToArray($xml)    {        //禁止引用外部xml实体        libxml_disable_entity_loader(true);        $xmlstring = simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA);        $val = json_decode(json_encode($xmlstring), true);        return $val;    }    //微信小程序接口    private function weixinapp()    {        //统一下单接口        $unifiedorder = $this->unifiedorder();//        print_r($unifiedorder);        $parameters = array(            'appId' => $this->appid, //小程序ID            'timeStamp' => '' . time() . '', //时间戳            'nonceStr' => $this->createNoncestr(), //随机串            'package' => 'prepay_id=' . $unifiedorder['prepay_id'], //数据包            'signType' => 'MD5'//签名方式        );        //签名        $parameters['paySign'] = $this->getSign($parameters);        return $parameters;    }    //作用：产生随机字符串，不长于32位    private function createNoncestr($length = 32)    {        $chars = "abcdefghijklmnopqrstuvwxyz0123456789";        $str = "";        for ($i = 0; $i < $length; $i++) {            $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);        }        return $str;    }    //作用：生成签名    private function getSign($Obj)    {        foreach ($Obj as $k => $v) {            $Parameters[$k] = $v;        }        //签名步骤一：按字典序排序参数        ksort($Parameters);        $String = $this->formatBizQueryParaMap($Parameters, false);        //签名步骤二：在string后加入KEY        $String = $String . "&key=" . $this->key;        //签名步骤三：MD5加密        $String = md5($String);        //签名步骤四：所有字符转为大写        $result_ = strtoupper($String);        return $result_;    }    ///作用：格式化参数，签名过程需要使用    private function formatBizQueryParaMap($paraMap, $urlencode)    {        $buff = "";        ksort($paraMap);        foreach ($paraMap as $k => $v) {            if ($urlencode) {                $v = urlencode($v);            }            $buff .= $k . "=" . $v . "&";        }        $reqPar = '';        if (strlen($buff) > 0) {            $reqPar = substr($buff, 0, strlen($buff) - 1);        }        return $reqPar;    }}

 支付回调代码如下：

$postXml = $GLOBALS["HTTP_RAW_POST_DATA"]; //接收微信参数// 接受不到参数可以使用file_get_contents("php://input"); PHP高版本中$GLOBALS好像已经被废弃了if (empty($postXml)) {    return false;}//将xml格式转换成数组function xmlToArray($xml) {    //禁止引用外部xml实体    libxml_disable_entity_loader(true);    $xmlstring = simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA);    $val = json_decode(json_encode($xmlstring), true);    return $val;}$attr = xmlToArray($postXml);$total_fee = $attr['total_fee'];$open_id = $attr['openid'];$itemid = $attr['out_trade_no'];$time = $attr['time_end'];

然后是你自己的逻辑处理。。。