php 下载重命名文件名

 public function dw($url,$name){

        $file_url = ROOT_PATH.'/public'.$url;
        $out_filename = $name.'.'.getExt($file_url);

        if(!file_exists($file_url)) {
            echo "不存在";
        }else{

            header('Accept-Ranges: bytes');

            header('Accept-Length: ' . filesize( $file_url ));

            header('Content-Transfer-Encoding: binary');

            header('Content-type: application/octet-stream');

            header('Content-Disposition: attachment; filename=' . $out_filename);

            header('Content-Type: application/octet-stream; name=' . $out_filename);

            if(is_file($file_url) && is_readable($file_url)){

                $file = fopen($file_url, "r");

                echo fread($file, filesize($file_url));

                fclose($file);
            }
        }

    }


function getExt($file){
    return end(explode(".",$file));
}