//数组转XML
  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;
  }

  //将XML转为array
  function xmlToArray($xml)
  {  
    //禁止引用外部xml实体
    libxml_disable_entity_loader(true);
    $values = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);    
    return $values;
  }