public function pay(){

        //获取openid

         if($_GET['code']){   //用code获取openid

             $code=$_GET['code'];

             $WX_APPID =C('WX_APPID');//appid

             $WX_SECRET = C('WX_SECRET');//AppSecret

             $url = "https://api.weixin.qq.com/sns/jscode2session?appid=" .$WX_APPID. "&secret=" .$WX_SECRET. "&js_code=" .$code. "&grant_type=authorization_code";

              $infos = json_decode(file_get_contents($url));

             $openid = $infos->openid;

        }

        if($_GET['uid']){

                $where['id']=$_GET['uid'];

        }

        $oid=$_GET['oid'];

        //$fee = $_GET['price'];

        $fee = 0.01;//举例支付0.01

        $time = time();

        $out_trade_no=$this->order_number($openid);

        $param = array(

        'appid' => '',//小程序id

        'mch_id'=>'1247127301',//商户 idC('WX_ID')

        'spbill_create_ip'=>$_SERVER['REMOTE_ADDR'],//终端ip

        'notify_url'=>'http://bzl.isoft.mobi/index.php/Home/Pay/notify', //回调通知地址

        'nonce_str'=> $this->createNoncestr(),//随机字符串

        'out_trade_no'=>$out_trade_no,//商户订单编号

        'total_fee'=>$fee*100, //总金额

        'openid'=>$openid,//用户openid

        'trade_type'=>'JSAPI',//交易类型

        'body' =>'XXX消费', //商品信息

        );

        $aa['id']=$oid;

        $da['out_trade_no']=$out_trade_no;

        $order =M('order')->where($aa)->save($da); //给订单里生成订单编号

         //通过签名算法计算得出的签名值，详见签名生成算法

        $param['sign'] = $this->getSign($param);

        //var_dump($param);die;

        //将数组内容转为xml格式，向微信发出请求

        $xmlData = $this->arrayToXml($param);

        $xml_result = $this->postXmlCurl($xmlData,'https://api.mch.weixin.qq.com/pay/unifiedorder',60);

       // var_dump($xml_result,$xmlData);die;

        $array = $this->xmlToArray($xml_result);

           if($array['return_code'] == 'SUCCESS' && $array['result_code'] == 'SUCCESS'){

            $time = time();

            $key=C('WX_KEY');

            $tmp = [];//临时数组用于签名

            $tmp['appId'] = ' ';

            $tmp['nonceStr'] = $array['nonce_str'];

            $tmp['package'] = 'prepay_id='.$array['prepay_id'];

            $tmp['signType'] = 'MD5';

            $tmp['timeStamp'] = (string)$time;

            $result['nonceStr'] = $array['nonce_str'];//随机字符串

            $result['signType'] = 'MD5';//签名算法，暂支持 MD5

            $result['package'] = 'prepay_id='.$array['prepay_id'];//统一下单接口返回的 prepay_id 参数值，提交格式如：prepay_id=*

            $result['paySign'] = $this->getSign($tmp);

            $result['timeStamp'] =(string)$time;

            $result['appId'] = $array['appid'];

     

     

        }else{

            $result['return_code'] = $array['return_code'];

            $result['return_msg'] = $array['return_msg'];

        }

        echo json_encode($result,JSON_UNESCAPED_UNICODE);

    }

    //生成订单号

    private function order_number($openid){

        //date('Ymd',time()).time().rand(10,99);//18位

        return md5($openid.time().rand(10,99));//32位

    }

    /*

    * 对要发送到微信统一下单接口的数据进行签名

    */

    protected function getSign($Obj){

        foreach ($Obj as $k => $v){

            $param[$k] = $v;

        }

        //签名步骤一：按字典序排序参数

        ksort($param);

        $String = $this->formatBizQueryParaMap($param, false);

        //签名步骤二：在string后加入KEY

        $wx_key=C('WX_KEY'); //申请支付后有给予一个商户账号和密码，登陆后自己设置的key

        $String = $String."&key=".$wx_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);

       // var_dump($result_);

        return $result_;

    }

    /*

     *排序并格式化参数方法，签名时需要使用

     */

    protected function formatBizQueryParaMap($paraMap, $urlencode){

        $buff = "";

        ksort($paraMap);

        foreach ($paraMap as $k => $v){

            if($urlencode){

                $v = urlencode($v);

            }

            //$buff .= strtolower($k) . "=" . $v . "&";

            $buff .= $k . "=" . $v . "&";

        }

        $reqPar = "";

        if (strlen($buff) > 0){

            $reqPar = substr($buff, 0, strlen($buff)-1);

        }

        return $reqPar;

    }

    /*

     * 生成随机字符串方法

     */

    protected 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;

    }

    //数组转字符串方法

    protected function arrayToXml($arr){

        $xml = "<xml>";

        foreach ($arr as $key=>$val)

        {

            if (is_numeric($val)){

                $xml.="<".$key.">".$val."</".$key.">";

            }else{

                $xml.="<".$key."><![CDATA[".$val."]]></".$key.">";

            }

        }

        $xml.="</xml>";

        return $xml;

    }

    //将xml字符串转换为数组

    protected static function xmlToArray($xml){

        $array_data = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);

        return $array_data;

    }

    //发送xml请求方法

    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");

        }

    }