php把读取xml 文档并转换成json数据代码

/*
<?xml version='1.0' encoding='utf-8' ?>
ps教程="20" maxPage="1" num="1" serverIP="58.57.65.195">

*/

<?php
$url = "https://www.111cn.net/xml.xml";

$dom = new DOMDocument();
$dom->load($url);
$root = $dom->documentElement;
$arr=array();
foreach ($root->childNodes as $item)
{
if($item->hasChildNodes())
{
$tmp=array();
foreach($item->childNodes as $one)
{
$tmp[$one->tagName]=$one->nodeValue;
}

$arr[$item->tagName]=$tmp;
}
}

$jsonStr = json_encode($arr);

var_dump($jsonStr);

/*

*/
?>