php得到文件类型mimetype

注意：大前提，已安装插件fileinfo

function get_mimetype($filename){
   if (is_file( $filename )) {
            $finfo = new \finfo(FILEINFO_MIME);
            $mimetype = $finfo->file($filename);
            $mimetypeParts = preg_split('/\s*[;,]\s*/', $mimetype);
            $result = strtolower($mimetypeParts[0]);
            unset($finfo);
            return $result;
    }
    return '';
}