PHP实例：PHP实现XML与数据格式进行转换类实例

<?php
/**
 * xml2array() will convert the given XML text to an array in the XML structure. 
 * Link: http://www.bin-co.com/php/scripts/xml2array/ 
 * Arguments : $contents - The XML text 
 * $get_attributes - 1 or 0. If this is 1 the function will get the attributes as well as the tag values - this results in a different array structure in the return value. 
 * $priority - Can be 'tag' or 'attribute'. This will change the way the resulting array sturcture. For 'tag', the tags are given more importance.
 * Return: The parsed XML in an array form. Use print_r() to see the resulting array structure. 
 * Examples: $array = xml2array(file_get_contents('feed.xml')); 
 * $array = xml2array(file_get_contents('feed.xml', 1, 'attribute'));
 */
function xml2array($contents, $get_attributes = 1, $priority = 'tag') {
  if (!$contents) return array();
  if (!function_exists('xml_parser_create')) {
    // print "'xml_parser_create()' function not found!";
    return array();
  } 
  // Get the XML parser of PHP - PHP must have this module for the parser to work
  $parser = xml_parser_create('');
  xml_parser_set_option($parser, XML_OPTION_TARGET_ENCODING, "UTF-8"); // http://minutillo.com/steve/weblog/2004/6/17/php-xml-and-character-encodings-a-tale-of-sadness-rage-and-data-loss 
  xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, 0);
  xml_parser_set_option($parser, XML_OPTION_SKIP_WHITE, 1);
  xml_parse_into_struct($parser, trim($contents), $xml_values);
  xml_parser_free($parser);
  if (!$xml_values) return; //Hmm... 
  // Initializations
  $xml_array = array();
  $parents = array();
  $opened_tags = array();
  $arr = array();
  $current = &$xml_array; //Refference 
  // Go through the tags.
  $repeated_tag_index = array(); //Multiple tags with same name will be turned into an array 
  foreach($xml_values as $data) {
    unset($attributes, $value); //Remove existing values, or there will be trouble 
    // This command will extract these variables into the foreach scope
    // tag(string), type(string), level(int), attributes(array).
    extract($data); //We could use the array by itself, but this cooler. 
    $result = array();
    $attributes_data = array();
    if (isset($value)) {
      if ($priority == 'tag') $result = $value;
      else $result['value'] = $value; //Put the value in a assoc array if we are in the 'Attribute' mode 
    } 
    // Set the attributes too.
    if (isset($attributes) and $get_attributes) {
      foreach($attributes as $attr => $val) {
        if ($priority == 'tag') $attributes_data[$attr] = $val;
        else $result['attr'][$attr] = $val; //Set all the attributes in a array called 'attr' 
      } 
    } 
    // See tag status and do the needed.
    if ($type == "open") { // The starting of the tag '<tag>'
      $parent[$level-1] = &$current;
      if (!is_array($current) or (!in_array($tag, array_keys($current)))) { // Insert New tag
        $current[$tag] = $result;
        if ($attributes_data) $current[$tag . '_attr'] = $attributes_data;
        $repeated_tag_index[$tag . '_' . $level] = 1;
        $current = &$current[$tag];
      } else { // There was another element with the same tag name
        if (isset($current[$tag][0])) { // If there is a 0th element it is already an array
          $current[$tag][$repeated_tag_index[$tag . '_' . $level]] = $result;
          $repeated_tag_index[$tag . '_' . $level]++;
        } else { // This section will make the value an array if multiple tags with the same name appear together
          $current[$tag] = array($current[$tag], $result); //This will combine the existing item and the new item together to make an array 
          $repeated_tag_index[$tag . '_' . $level] = 2;
          if (isset($current[$tag . '_attr'])) { // The attribute of the last(0th) tag must be moved as well
            $current[$tag]['0_attr'] = $current[$tag . '_attr'];
            unset($current[$tag . '_attr']);
          } 
        } 
        $last_item_index = $repeated_tag_index[$tag . '_' . $level]-1;
        $current = &$current[$tag][$last_item_index];
      } 
    } elseif ($type == "complete") { // Tags that ends in 1 line '<tag />'
      // See if the key is already taken.
      if (!isset($current[$tag])) { // New Key
        $current[$tag] = $result;
        $repeated_tag_index[$tag . '_' . $level] = 1;
        if ($priority == 'tag' and $attributes_data) $current[$tag . '_attr'] = $attributes_data;
      } else { // If taken, put all things inside a list(array)
        if (isset($current[$tag][0]) and is_array($current[$tag])) { // If it is already an array...
          // ...push the new element into that array.
          $current[$tag][$repeated_tag_index[$tag . '_' . $level]] = $result;
          if ($priority == 'tag' and $get_attributes and $attributes_data) {
            $current[$tag][$repeated_tag_index[$tag . '_' . $level] . '_attr'] = $attributes_data;
          } 
          $repeated_tag_index[$tag . '_' . $level]++;
        } else { // If it is not an array...
          $current[$tag] = array($current[$tag], $result); //...Make it an array using using the existing value and the new value 
          $repeated_tag_index[$tag . '_' . $level] = 1;
          if ($priority == 'tag' and $get_attributes) {
            if (isset($current[$tag . '_attr'])) { // The attribute of the last(0th) tag must be moved as well
              $current[$tag]['0_attr'] = $current[$tag . '_attr'];
              unset($current[$tag . '_attr']);
            } 
            if ($attributes_data) {
              $current[$tag][$repeated_tag_index[$tag . '_' . $level] . '_attr'] = $attributes_data;
            } 
          } 
          $repeated_tag_index[$tag . '_' . $level]++; //0 and 1 index is already taken 
        } 
      } 
    } elseif ($type == 'close') { // End of tag '</tag>'
      $current = &$parent[$level-1];
    } 
  } 
  return($xml_array);
} 
// Array to XML
class array2xml {
  public $output = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n";
  public $sub_item = array();
  public function __construct($array) {
    $sub_item = array();
    $this->output .= $this->xmlmake($array);
  } 
  public function xmlmake($array, $fk = '') {
    $xml = '';
    global $sub_item;
    foreach ($array as $key => $value) {
      if (is_array($value)) {
        if (is_numeric($key)) {
          $this->sub_item=array_merge($this->sub_item,array($fk));
          $xml .= "<{$fk}>" . $this->xmlmake($value, $key) . "</{$fk}>";
        } else {
          $xml .= "<{$key}>" . $this->xmlmake($value, $key) . "</{$key}>";
        } 
      } else {
        $xml .= "<{$key}>{$value}</{$key}>\n";
      } 
    } 
    return $xml;
  } 
  public function output(){
    foreach($this->sub_item as $t){
      $this->output = str_replace("<{$t}><{$t}>","<{$t}>",$this->output);
      $this->output = str_replace("</{$t}></{$t}>","</{$t}>",$this->output);
    }
    return $this->output;
  }
}