xml Array 相互转化

public function xmlToArray($xml)
    {        
        //将XML转为array        
        $array_data = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);        
        return $array_data;
    }

function arrayToXml($arr)
    {
        $xml = "<xml>";
        foreach ($arr as $key=>$val)
        {
             if (is_numeric($val))
             {
                 $xml.="<".$key.">".$val."</".$key.">"; 

             }
             else
                 $xml.="<".$key."><![CDATA[".$val."]]></".$key.">";  
        }
        $xml.="</xml>";
        return $xml; 
    }