from xml

/**
* 将xml转为array
* @param string $xml
* @throws WxPayException
*/
public function FromXml($xml)
{
if(!$xml){
throw new WxPayException("xml数据异常！");
}
//将XML转为array
//禁止引用外部xml实体
libxml_disable_entity_loader(true);
$this->values = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);
return $this->values;
}