支付的签名

public function MakeSign($data)
    {
        //签名步骤一：按字典序排序参数
        ksort($data);
        $string = $this->ToUrlParams($data);
        //print_r($string);
        //签名步骤二：在string后加入KEY
        $string = $string . "&key=tianxunhuliantianxunhuliantianxu";
        //print_r($string);
        //签名步骤三：MD5加密
        $string = md5($string);
        //print_r($string);
        //签名步骤四：所有字符转为大写
        $result = strtoupper($string);
        //print_r($result);
        return $result;
    }

/**
     * 格式化参数格式化成url参数
     */
    public function ToUrlParams($data)
    {
        $buff = "";
        foreach ($data as $k => $v)
        {
            if($k != "sign" && $v != "" && !is_array($v)){
                $buff .= $k . "=" . $v . "&";
            }
        }
        
        $buff = trim($buff, "&");
        return $buff;
    }

/**
     * 
     * 产生随机字符串，不长于32位
     * @param int $length
     * @return 产生的随机字符串
     */
    public static function getNonceStr($length = 32) 
    {
        $chars = "abcdefghijklmnopqrstuvwxyz0123456789";  
        $str ="";
        for ( $i = 0; $i < $length; $i++ )  {  
            $str .= substr($chars, mt_rand(0, strlen($chars)-1), 1);  
        } 
        return $str;
    }

function arrayToXml($arr){ 
        $xml = "<xml>"; 
        foreach ($arr as $key=>$val){ 
        if(is_array($val)){ 
                $xml.="<".$key.">".arrayToXml($val)."</".$key.">"; 
            }else{ 
                $xml.="<".$key.">".$val."</".$key.">"; 
            } 
        } 
        $xml.="</xml>"; 
        return $xml; 
    }

//  微信post数组，订单号，商品金额
    public function getWxPay($post,$order_sn){
        $client_ip = $_SERVER["REMOTE_ADDR"];  //客户端ip
        $data[‘appid‘] = "";//appid
        $data[‘mch_id‘] = "";//商户号
        $data[‘nonce_str‘] = $this->getNonceStr();  //随机32位字符串
        $data[‘body‘] = ‘xmm-‘.$order_sn;
        $data[‘out_trade_no‘] = $order_sn;
        $data[‘total_fee‘] = $post[‘goods_price‘]*100;  //注意 单位是分
        $data[‘spbill_create_ip‘] = $client_ip;
        $data[‘notify_url‘] = "http://域名/api/register/notify";
        $data[‘trade_type‘] = "APP";  //交易类型
        $data[‘attach‘]="app_flash";
        //print_r($data);
        $data[‘sign‘] = $this->MakeSign($data);
        $xml = $this->arrayToXml($data);
        //print_r($xml);
        $url = "https://api.mch.weixin.qq.com/pay/unifiedorder";
        $request = $this->postXmlCurl($xml,$url);
        //print_r($request);
        return $this->FromXml($request);
    }