public static function strToGBK($strText)    {        $encode = mb_detect_encoding($strText, array('UTF-8','GB2312','GBK'));        if($encode == "UTF-8")        {            return @iconv('UTF-8','GB18030',$strText);        }        else        {            return $strText;        }    }

mb_detect_encoding：检测字符的编码