PHP基于dom实现图书xml格式数据示例有哪些？

<?php
 $books = array();
 $books [] = array(
 'title' => 'PHP Hacks',
 'author' => 'Jack Herrington',
 'publisher' => "O'Reilly"
 );
 $books [] = array(
 'title' => 'Podcasting Hacks',
 'author' => 'Jack Herrington',
 'publisher' => "O'Reilly"
 );
 $doc = new DOMDocument();
 $doc->formatOutput = true;
 $r = $doc->createElement( "books" );
 $doc->appendChild( $r );
 foreach( $books as $book )
 {
 $b = $doc->createElement( "book" );
 $author = $doc->createElement( "author" );
 $author->appendChild(
 $doc->createTextNode( $book['author'] )
 );
 $b->appendChild( $author );
 $title = $doc->createElement( "title" );
 $title->appendChild(
 $doc->createTextNode( $book['title'] )
 );
 $b->appendChild( $title );
 $publisher = $doc->createElement( "publisher" );
 $publisher->appendChild(
 $doc->createTextNode( $book['publisher'] )
 );
 $b->appendChild( $publisher );
 $r->appendChild( $b );
 }
 echo $doc->saveXML();
?>

<?xml version="1.0"?>
<books>
 <book>
 <author>Jack Herrington</author>
 <title>PHP Hacks</title>
 <publisher>O'Reilly</publisher>
 </book>
 <book>
 <author>Jack Herrington</author>
 <title>Podcasting Hacks</title>
 <publisher>O'Reilly</publisher>
 </book>
</books>