一个操作xml的类

<?
/*
(c) 2000 Hans Anderson Corporation.  All Rights Reserved.
You are free to use and modify this class under the same
guidelines found in the PHP License.

-----------

bugs/me:
http://www.hansanderson.com/php/
[email protected]
[email protected]

-----------

Version 1.0

- 1.0 is the first actual release of the class.  It's  
finally what I was hoping it would be, though there
are likely to still be some bugs in it.  This is
a much changed version, and if you have downloaded
a previous version, this WON'T work with your existing
scripts!  You'll need to make some SIMPLE changes.

- .92 fixed bug that didn't include tag attributes

(to use attributes, add _attributes[array_index]
to the end of the tag in question:
$xml_html_head_body_img would become
$xml_html_head_body_img_attributes[0],  
for example)

-- Thanks to Nick Winfield <[email protected]>
for reporting this bug.

- .91 No Longer requires PHP4!

- .91 now all elements are array.  Using objects has
been discontinued.
*/

class xml_container{

function store($k,$v) {
$this->{$k}[] = $v;
}
}

/* parses the information */
/*********************************
*    类定义开始
*
*********************************/
class xml{

// initialize some variables
var $current_tag=array();
var $xml_parser;
var $Version = 1.0;
var $tagtracker = array();

/* Here are the XML functions needed by expat */

/* when expat hits an opening tag, it fires up this function */
function startElement($parser, $name, $attrs){

array_push($this->current_tag, $name); // add tag to the cur. tag array
$curtag = implode("_",$this->current_tag); // piece together tag

/* this tracks what array index we are on for this tag */

if(isset($this->tagtracker["$curtag"])) {
$this->tagtracker["$curtag"]++;
}
else{
$this->tagtracker["$curtag"]=0;
}

/* if there are attributes for this tag, we set them here. */

if(count($attrs)>0) {
$j = $this->tagtracker["$curtag"];
if(!$j) $j = 0;

if(!is_object($GLOBALS[$this->identifier]["$curtag"][$j])) {
$GLOBALS[$this->identifier]["$curtag"][$j] = new xml_container;
}

$GLOBALS[$this->identifier]["$curtag"][$j]->store("attributes",$attrs);
}

}// end function startElement

/* when expat hits a closing tag, it fires up this function */
function endElement($parser, $name) {
$curtag = implode("_",$this->current_tag); // piece together tag

// before we pop it off,
// so we can get the correct
// cdata

if(!$this->tagdata["$curtag"]) {
$popped = array_pop($this->current_tag); // or else we screw up where we are
return; // if we have no data for the tag
}
else{
$TD = $this->tagdata["$curtag"];
unset($this->tagdata["$curtag"]);
}

$popped = array_pop($this->current_tag);
// we want the tag name for
// the tag above this, it  
// allows us to group the
// tags together in a more
// intuitive way.

if(sizeof($this->current_tag) == 0) return; // if we aren't in a tag

$curtag = implode("_",$this->current_tag); // piece together tag
// this time for the arrays

$j = $this->tagtracker["$curtag"];

if(!$j) $j = 0;

if(!is_object($GLOBALS[$this->identifier]["$curtag"][$j])) {
$GLOBALS[$this->identifier]["$curtag"][$j] = new xml_container;
}

$GLOBALS[$this->identifier]["$curtag"][$j]->store($name,$TD);
#$this->tagdata["$curtag"]);
unset($TD);
return TRUE;
} // end function endElement

/* when expat finds some internal tag character data,
it fires up this function */

function characterData($parser, $cdata) {
$curtag = implode("_",$this->current_tag); // piece together tag
$this->tagdata["$curtag"] .= $cdata;
}

function xml($data,$identifier='xml') {   

$this->identifier = $identifier;

// create parser object
$this->xml_parser = xml_parser_create();

// set up some options and handlers
xml_set_object($this->xml_parser,$this);
xml_parser_set_option($this->xml_parser,XML_OPTION_CASE_FOLDING,0);
xml_set_element_handler($this->xml_parser, "startElement", "endElement");
xml_set_character_data_handler($this->xml_parser, "characterData");

if (!xml_parse($this->xml_parser, $data, TRUE)) {
sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($this->xml_parser)),
xml_get_current_line_number($this->xml_parser));
}

// we are done with the parser, so let's free it
xml_parser_free($this->xml_parser);

}//end constructor: function xml()

}//thus, we end our class xml

?>

操作方法：

require('class.xml.php');
$file = "data.xml";
$data = implode("",file($file)) or die("could not open XML input file");
$obj = new xml($data,"xml");

print $xml["hans"][0]->num_results[0];
for($i=0;$i<sizeof($xml["hans"]);$i++) {
print $xml["hans"][$i]->tag[0] . " ";
}

To print url attributes (if they exist):

print $xml["hans"][0]->attributes[0]["size"];