参考http://blog.csdn.net/k8080880/article/details/47616461
创建

<?php
    $file = 'index.xml'; 
    $idValue = "1"; 
    $urlValue = 'http://www.baidu.com';  
    $contentValue = "百度"; 

    $newIdValue = "2";
    $newUrlValue = "http://google.cn";
    $newContentValue = "谷歌";

    $doc = new DOMDocument('1.0', 'utf-8');  
    $doc -> formatOutput = true;

    $root = $doc -> createElement('root');//新建节点  
    $test = $doc -> createElement('test');//新建节点  

    $url = $doc -> createAttribute('url');//新建属性  
    $urlValueNode = $doc -> createTextNode($urlValue);//新建TEXT值  
    $url -> appendChild($urlValueNode);//将$patch文本设为$url属性的值  
        
    $id = $doc -> createAttribute('id');   
    $idValueNode = $doc -> createTextNode($idValue);   
    $id -> appendChild($idValueNode);

    $content = $doc -> createTextNode($contentValue);//节点值    
       
    $test -> appendChild($url);//将$url设为index节点的属性，以下类同  
    $test -> appendChild($id);
    $test -> appendChild($content); 
    $root -> appendChild($test);//设置index为root子节点  
    $doc -> appendChild($root);//设置root为跟节点 

    $doc -> save($file);//保存文件  
       
    echo '创建成功'."\n"; 
?>

增加

<?php
    $file = 'index.xml'; 
    $idValue = "1"; 
    $urlValue = 'http://www.baidu.com';  
    $contentValue = "百度"; 

    $newIdValue = "2";
    $newUrlValue = "http://google.cn";
    $newContentValue = "谷歌";

    $doc = new DOMDocument('1.0', 'utf-8');  
    $doc -> formatOutput = true;

    if($doc->load($file)) {
        $root = $doc -> documentElement;//获得根节点(root)  

        $test = $doc -> createElement('test');

        $url = $doc -> createAttribute('url');
        $newUrlValueNode = $doc -> createTextNode($newUrlValue);   
        $url -> appendChild($newUrlValueNode);

        $id = $doc -> createAttribute('id');   
        $newIdValueNode = $doc -> createTextNode($newIdValue);   
        $id -> appendChild($newIdValueNode);

        $content = $doc -> createTextNode($newContentValue);//节点值  

        $test -> appendChild($url);
        $test -> appendChild($id);
        $test -> appendChild($content);
        $root -> appendChild($test);
        $doc -> save($file); 

        echo "添加成功"."\n"; 
    }
?>

修改

<?php
    $file = 'index.xml'; 
    $idValue = "1"; 
    $urlValue = 'http://www.baidu.com';  
    $contentValue = "百度"; 

    $newIdValue = "2";
    $newUrlValue = "http://google.cn";
    $newContentValue = "谷歌";

    $doc = new DOMDocument('1.0', 'utf-8');  
    $doc -> formatOutput = true;

    if($doc->load($file)) {
        $isExist = false;
        $root = $doc -> documentElement;//获得根节点(root)  
        $elm = $root -> getElementsByTagName('test');
        foreach ($elm as $item) {   
            if($item -> getAttribute('id') == $idValue) {   
                $item -> setAttribute('url', $newUrlValue);   
                $item -> nodeValue = $newContentValue;//修改节点值

                $title = $doc -> createAttribute('title');//新建属性  
                $titleValueNode = $doc -> createTextNode("标题");//新建TEXT值  
                $title -> appendChild($titleValueNode);//将$patch文本设为$url属性的值 

                $item -> appendChild($title);

                $isExist = true;   
            }   
        }   
        if(!$isExist) {   
            echo "没有找到节点";   
        } else {   
            $doc -> save($file);   
            echo "修改成功";     
        }
    }
?>

删除

<?php
    $file = 'index.xml'; 
    $idValue = "1"; 
    $urlValue = 'http://www.baidu.com';  
    $contentValue = "百度"; 

    $newIdValue = "2";
    $newUrlValue = "http://google.cn";
    $newContentValue = "谷歌";

    $doc = new DOMDocument('1.0', 'utf-8');  
    $doc -> formatOutput = true;

    if($doc->load($file)) {
        $root = $doc -> documentElement;//获得根节点(root)  
        $elm = $root -> getElementsByTagName('test');
        foreach ($elm as $item) {   
            if($item -> getAttribute('id') == $newIdValue) { 
                if($root -> removeChild($item)) { 
                    echo "删除成功";
                } else {   
                    echo '删除失败';   
                } 
                $item -> setAttribute('url', $idValue);   
                $item -> nodeValue = $contentValue;//修改节点值
                //$item -> removeChild($item -> nodevalue); 
            }   
        }   
    
        $doc -> save($file); 
    }
?>