php修改xml文件的方法：首先打开xml文件；然后遍历一下xml文档；接着对xml文件内容进行重新赋值；最后保存文件即可。

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PHP 修改和删除XML内容的原理和方法

例如：

example.xml

<?xml version="1.0" encoding="utf-8"?><root>
 <book id="1">
 <title>title1</title>
 </book>
 <book id="2">
 <title>title2</title>
 </book>
 <book id="3">
 <title>title3</title>
 </book>
 <book id="4">
 <title>title4</title>
 </book>
 <book id="5">
 <title>title5</title>
 </book></root>

首先遍历一下该xml文档

<?php

 $doc = new DOMDocument(); 
 $doc->load('example.xml'); 
 $books = $doc -> getElementsByTagName("book"); 
 //遍历
 foreach ($books as $book) { 
 echo $book->getAttribute('id')."-"; 
 echo $book->getElementsByTagName("title")->item(0)->nodeValue; 
 echo "<br>";
 }

运行结果为：

1-title1
2-title2
3-title3
4-title4
5-title5

修改：

<?php $doc = new DOMDocument(); $doc->load('example.xml'); 
$books = $doc -> getElementsByTagName("book"); 
//遍历
 foreach ($books as $book) { 
 //将id=3的title设置为33333
 if($book->getAttribute('id')==3){
 echo $book->getAttribute('id')."-";
 echo $book->getElementsByTagName("title")->item(0)->nodeValue="33333";
 echo "<br>";
 }
 } 
 //对文件做修改后，一定要记得重新sava一下，才能修改掉原文件
 $doc -> save('example.xml');

修改之后为：

<?xml version="1.0" encoding="utf-8"?><root>
 <book id="1">
 <title>title1</title>
 </book>
 <book id="2">
 <title>title2</title>
 </book>
 <book id="3">
 <title>33333</title>
 </book>
 <book id="4">
 <title>title4</title>
 </book>
 <book id="5">
 <title>title5</title>
 </book></root>

删除操作：

<?php $doc = new DOMDocument(); 
$doc->load('example.xml'); 
$root = $doc -> documentElement;
//根标签 
 $books = $doc -> getElementsByTagName("book"); 
 //遍历
 foreach ($books as $book) { 
 //将id=4的删除
 if($book->getAttribute('id')==4){ 
 $root->removeChild($book);
 }
 } //对文件做修改后，一定要记得重新sava一下，才能修改掉原文件
 $doc -> save('example.xml');

删除后的结果为：

<?xml version="1.0" encoding="utf-8"?><root>
 <book id="1">
 <title>title1</title>
 </book>
 <book id="2">
 <title>title2</title>
 </book>
 <book id="3">
 <title>33333</title>
 </book>

 <book id="5">
 <title>title5</title>
 </book></root>