php下载小文件

    public function loadMessagePrompt()
    {
        $file = ROOT_PATH . 'public' . $this->chat_config['ringing'];
        header("Content-type:application/octet-stream");
        $filename = basename($file);
        header("Content-Disposition:attachment;filename = " . $filename);
        header("Accept-ranges:bytes");
        header("Accept-length:" . filesize($file));
        readfile($file);
    }