转载链接：http://zyan.cc/post/253

今天在PHP4环境下重新写一个接口程序，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 Library, by Keith Devens, version 1.2b   
# <a href="http://keithdevens.com/software/phpxml" target="_blank">http://keithdevens.com/software/phpxml</a>   
#   
# This code is Open Source, released under terms similar to the Artistic License.   
# Read the license at <a href="http://keithdevens.com/software/license" target="_blank">http://keithdevens.com/software/license</a>   
#   
###################################################################################   ###################################################################################   
# 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;   
}   
?>