本文实例讲述了PHP实现的XML操作类。分享给大家供大家参考，具体如下：

这是一个接口程序，需要大量分析解析XML，PHP的xml_parse_into_struct()函数不能直接生成便于使用的数组，而SimpleXML扩展在PHP5中才支持，于是逛逛搜索引擎，在老外的网站上找到了一个不错的PHP XML操作类。

一、用法举例：

1、将XML文件解释成便于使用的数组：

<?php
include('xml.php'); //引用PHP XML操作类
$xml = file_get_contents('data.xml'); //读取XML文件
//$xml = file_get_contents("php://input"); //读取POST过来的输入流
$data=XML_unserialize($xml);
echo '<pre>';
print_r($data);
echo '</pre>';
?>

data.xml文件：

<?xml version="1.0" encoding="GBK"?>
<video>
<upload>
<videoid>998</videoid>
<name><![CDATA[回忆未来]]></name>
<memo><![CDATA[def]]></memo>
<up_userid>11317</up_userid>
</upload>
</video>

利用该XML操作类生成的对应数组（汉字编码：UTF-8）：

Array
(
 [video] => Array
  (
   [upload] => Array
    (
     [videoid] => 998
     [name] => 回忆未来
     [memo] => def
     [up_userid] => 11317
    )
  )
)

2、将数组转换成XML文件：

<?php
include('xml.php');//引用PHP XML操作类
$xml = XML_serialize($data);
?>

二、PHP XML操作类源代码：

<?php
###################################################################################
# XML_unserialize: takes raw XML as a parameter (a string)
# and returns an equivalent PHP data structure
###################################################################################
function & XML_unserialize(&$xml){
 $xml_parser = &new XML();
 $data = &$xml_parser->parse($xml);
 $xml_parser->destruct();
 return $data;
}
###################################################################################
# XML_serialize: serializes any PHP data structure into XML
# Takes one parameter: the data to serialize. Must be an array.
###################################################################################
function & XML_serialize(&$data, $level = 0, $prior_key = NULL){
 if($level == 0){ ob_start(); echo '<?xml version="1.0" ?>',"n"; }
 while(list($key, $value) = each($data))
  if(!strpos($key, ' attr')) #if it's not an attribute
   #we don't treat attributes by themselves, so for an emptyempty element
   # that has attributes you still need to set the element to NULL
   if(is_array($value) and array_key_exists(0, $value)){
    XML_serialize($value, $level, $key);
   }else{
    $tag = $prior_key ? $prior_key : $key;
    echo str_repeat("t", $level),'<',$tag;
    if(array_key_exists("$key attr", $data)){ #if there's an attribute for this element
     while(list($attr_name, $attr_value) = each($data["$key attr"]))
      echo ' ',$attr_name,'="',htmlspecialchars($attr_value),'"';
     reset($data["$key attr"]);
    }
    if(is_null($value)) echo " />n";
    elseif(!is_array($value)) echo '>',htmlspecialchars($value),"</$tag>n";
    else echo ">n",XML_serialize($value, $level+1),str_repeat("t", $level),"</$tag>n";
   }
 reset($data);
 if($level == 0){ $str = &ob_get_contents(); ob_end_clean(); return $str; }
}
###################################################################################
# XML class: utility class to be used with PHP's XML handling functions
###################################################################################
class XML{
 var $parser; #a reference to the XML parser
 var $document; #the entire XML structure built up so far
 var $parent; #a pointer to the current parent - the parent will be an array
 var $stack; #a stack of the most recent parent at each nesting level
 var $last_opened_tag; #keeps track of the last tag opened.
 function XML(){
   $this->parser = &xml_parser_create();
  xml_parser_set_option(&$this->parser, XML_OPTION_CASE_FOLDING, false);
  xml_set_object(&$this->parser, &$this);
  xml_set_element_handler(&$this->parser, 'open','close');
  xml_set_character_data_handler(&$this->parser, 'data');
 }
 function destruct(){ xml_parser_free(&$this->parser); }
 function & parse(&$data){
  $this->document = array();
  $this->stack = array();
  $this->parent = &$this->document;
  return xml_parse(&$this->parser, &$data, true) ? $this->document : NULL;
 }
 function open(&$parser, $tag, $attributes){
  $this->data = ''; #stores temporary cdata
  $this->last_opened_tag = $tag;
  if(is_array($this->parent) and array_key_exists($tag,$this->parent)){ #if you've seen this tag before
   if(is_array($this->parent[$tag]) and array_key_exists(0,$this->parent[$tag])){ #if the keys are numeric
    #this is the third or later instance of $tag we've come across
    $key = count_numeric_items($this->parent[$tag]);
   }else{
    #this is the second instance of $tag that we've seen. shift around
    if(array_key_exists("$tag attr",$this->parent)){
     $arr = array('0 attr'=>&$this->parent["$tag attr"], &$this->parent[$tag]);
     unset($this->parent["$tag attr"]);
    }else{
     $arr = array(&$this->parent[$tag]);
    }
    $this->parent[$tag] = &$arr;
    $key = 1;
   }
   $this->parent = &$this->parent[$tag];
  }else{
   $key = $tag;
  }
  if($attributes) $this->parent["$key attr"] = $attributes;
  $this->parent = &$this->parent[$key];
  $this->stack[] = &$this->parent;
 }
 function data(&$parser, $data){
  if($this->last_opened_tag != NULL) #you don't need to store whitespace in between tags
   $this->data .= $data;
 }
 function close(&$parser, $tag){
  if($this->last_opened_tag == $tag){
   $this->parent = $this->data;
   $this->last_opened_tag = NULL;
  }
  array_pop($this->stack);
  if($this->stack) $this->parent = &$this->stack[count($this->stack)-1];
 }
}
function count_numeric_items(&$array){
 return is_array($array) ? count(array_filter(array_keys($array), 'is_numeric')) : 0;
}
?>

PS：这里再为大家提供几款关于xml操作的在线工具供大家参考使用：

在线XML/JSON互相转换工具：
http://tools.gimoo.net/code/xmljson

在线格式化XML/在线压缩XML：
http://tools.gimoo.net/code/xmlformat

XML在线压缩/格式化工具：
http://tools.gimoo.net/code/xml_format_compress

XML代码在线格式化美化工具：
http://tools.gimoo.net/code/xmlcodeformat

更多关于PHP相关内容感兴趣的读者可查看本站专题：《PHP针对XML文件操作技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》、《PHP错误与异常处理方法总结》、《PHP运算与运算符用法总结》、《PHP网络编程技巧总结》、《PHP基本语法入门教程》、《php面向对象程序设计入门教程》、《php+mysql数据库操作入门教程》及《php常见数据库操作技巧汇总》

希望本文所述对大家PHP程序设计有所帮助。