**
 * 文件:WxPayPubHelper.php
 * 统一支付接口类
 * Class UnifiedOrder_pub
 */
class UnifiedOrder_pub extends Wxpay_client_pub
{
    public function __construct()
    {
        //设置接口链接
        $this->url = "https://api.mch.weixin.qq.com/pay/unifiedorder";
        //设置curl超时时间
        $this->curl_timeout = WxPayConf_pub::getParams(‘curl_timeout‘);
    }

    /**
     * 生成接口参数xml
     * @return string|void
     */
    public function createXml()
    {
        try {
            //检测必填参数
            if ($this->parameters["out_trade_no"] == null) {
                throw new SDKRuntimeException("缺少统一支付接口必填参数out_trade_no！" . "<br>");
            } elseif ($this->parameters["body"] == null) {
                throw new SDKRuntimeException("缺少统一支付接口必填参数body！" . "<br>");
            } elseif ($this->parameters["total_fee"] == null) {
                throw new SDKRuntimeException("缺少统一支付接口必填参数total_fee！" . "<br>");
            } elseif ($this->parameters["notify_url"] == null) {
                throw new SDKRuntimeException("缺少统一支付接口必填参数notify_url！" . "<br>");
            } elseif ($this->parameters["trade_type"] == null) {
                throw new SDKRuntimeException("缺少统一支付接口必填参数trade_type！" . "<br>");
            } elseif ($this->parameters["trade_type"] == "JSAPI" &&
                $this->parameters["openid"] == NULL
            ) {
                throw new SDKRuntimeException("统一支付接口中，缺少必填参数openid！trade_type为JSAPI时，openid为必填参数！" . "<br>");
            }
/************************************服务商模式修改***********************************/
        if(WxPayConf_pub::getParams(‘sub_mchid‘)){      //服务商模式
           
            $this->parameters["sub_mch_id"] = WxPayConf_pub::getParams(‘sub_mchid‘);
            $this->parameters["sub_appid"] = WxPayConf_pub::getParams(‘sub_appid‘);
            $this->parameters["sub_openid"] = $this->parameters["openid"];
            unset($this->parameters["openid"]);//去掉原来的openid
        }
/************************************服务商模式修改结束***********************************/


            $this->parameters["appid"] = WxPayConf_pub::getParams(‘appid‘);//公众账号ID
            $this->parameters["mch_id"] = WxPayConf_pub::getParams(‘mchid‘);//商户号
            $this->parameters["spbill_create_ip"] = $_SERVER[‘REMOTE_ADDR‘];//终端ip
            $this->parameters["nonce_str"] = $this->createNoncestr();//随机字符串
            $this->parameters["sign"] = $this->getSign($this->parameters);//签名
            return $this->arrayToXml($this->parameters);
        } catch (SDKRuntimeException $e) {
            die($e->errorMessage());
        }
    }