php获取xml属性值

<!-- xml格式
<foo xmlns="test">
<bar attr='a'></bar>
<bar attr='b'></bar>
<bar attr='c'></bar>
</foo>
-->
<?php
$dom = new DOMDocument();
if (!$dom->load('attr.xml'))
{
echo "load books.xml failed!<br>";
return;
}

$foos = $dom->getElementsByTagName('foo');
$var = $foos->item(0)->getAttribute('xmlns');
echo 'var=' . $var . '<br>';
/*foreach ($foos as $foo)
{
$var = $foo->getAttribute('xmlns');
echo 'var=' . $var . '<br>';
}*/
$bars = $dom->getElementsByTagName('bar');

foreach ($bars as $bar)
{
$arr[] = $bar->getAttribute('attr');
}

var_dump($arr);
?>