从 xml 文件中检索主要记录/项目标签名称

Question

我是 xml 解析和 xpath 的新手。我需要制作一个可以找到记录标签名称的解析器。例如，如果给定这个 xml：

<?xml version="1.0" encoding="ISO-8859-1"?>
<items>
<item>
  <name>first item</name>
  <description>first item description</description>
</item>
<item>
  <name>second item</name>
  <description>second item description</description>
</item>
</items>

脚本应该能够确定 "item" 是我要查找的标签名称，而无需在代码中的某处指定它。对我来说，每个“item”元素都是一条记录；给定 xml 的示例响应将是“found 2 items”。

这可以用 xpath 和 php 完成吗？

我正在为我的解析器使用 xmlreader。

Answer 1

<?
  $dom = simplexml_load_file("lectures.xml");
  $items = 0;

  foreach ($dom->item as $item) {
    //what u want to do here
    $items += 1;
  }
?>

我认为您不需要 xpath，最好在您想在大 xml 文件中查找特定元素时使用它。

xpath query: /child::items/child::item

Answer 2

你可以使用这个库将xml转换为php数组

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); 
}  

$xml = xml2array('[xml 内容]');

现在可以轻松使用 foreach :)