php如何删除xml节点

$doc = new DOMDocument(); $doc->load('bird_base.xml'); $root = $doc->getElementsByTagName('birdList'); $root = $root->item(0); $bird = $root->getElementsByTagName('bird'); //遍历所有 bird 节点 foreach ($bird as $rootdata) { //遍历每一个 bird 节点所有属性 $speciesID= $rootdata->getElementsByTagName('speciesID')->item(0)->nodeValue; $localName= $rootdata->getElementsByTagName('localName')->item(0)->nodeValue; $engName= $rootdata->getElementsByTagName('engName')->item(0)->nodeValue; $latinName= $rootdata->getElementsByTagName('latinName')->item(0)->nodeValue; $bird = $this->bird->get_bird_detail($speciesID); if(!empty($bird)) { //修改节点值 $rootdata->getElementsByTagName('localName')->item(0)->nodeValue = $bird['localName']; $rootdata->getElementsByTagName('engName')->item(0)->nodeValue = $bird['engName']; $rootdata->getElementsByTagName('latinName')->item(0)->nodeValue = $bird['latinName']; }else { //删除节点 $rootdata->parentNode->removeChild($rootdata); } } $doc->save('bird_base.xml'); bird_base.xml 示例    1 雪鹑 Snow Partridge Lerwa lerwa   2 藏雪鸡 Tibetan Snowcock Tetraogallus tibetanus