//数组转字符串方法
protected 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;
}

protected function xmlToArray($xml)
{
    $array_data = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);
    return $array_data;
}