public function createUnifiedOrder($out_trade_no, $subject, $total_fee, $open_id = null)
{
//②、统一下单
$input = new \WxPayUnifiedOrder();
$input->setWxPayApi($this->wxPayApi);
$input->SetBody($subject);
$input->SetOut_trade_no($out_trade_no);
// $input->SetTotal_fee($total_fee);
$input->SetTotal_fee(intval($total_fee * 100));
$input->SetTime_start(date("YmdHis"));
$input->SetTime_expire(date("YmdHis", time() + 600));
$input->SetTrade_type($this->trade_type);
if ($open_id) {
$input->SetOpenid($open_id);
}
$order = $this->wxPayApi->unifiedOrder($input);
return $order;
}