如何改成 x-www-form-urlencoded 提交方式

我这是个方法是from-data的提交方式吗，如何改成x-www-form-urlencoded

    protected  function buildForm($data, $gateway) {

        $sHtml = "<form id='paysubmit' name='bankPaySubmit' action='".$gateway."' method='post'>";

        foreach ($data as $key => $val) {
              $sHtml.= '<input type="hidden" name="' . $key . '" value="' . $val . '">';
        }
        $sHtml.= "</form>";
        $sHtml.= "<script>document.forms['bankPaySubmit'].submit();</script>";

        return $sHtml;
    }