这适用于关联数组。

    function array2xml($array, $node_name="root") {
    $dom = new DOMDocument('1.0', 'UTF-8');
    $dom->formatOutput = true;
    $root = $dom->createElement($node_name);
    $dom->appendChild($root);

    $array2xml = function ($node, $array) use ($dom, &$array2xml) {
        foreach($array as $key => $value){
            if ( is_array($value) ) {
                $n = $dom->createElement($key);
                $node->appendChild($n);
                $array2xml($n, $value);
            }else{
                $attr = $dom->createAttribute($key);
                $attr->value = $value;
                $node->appendChild($attr);
            }
        }
    };

    $array2xml($root, $array);

    return $dom->saveXML();
}