<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0" xmlns:wfw="http://wellformedweb.org/CommentAPI/"></rss>

<?php 
class Rss{
  protected $dom = null;
  protected $temp = './feed.xml';
  protected $rss = null;
  protected $title = '';
  protected $desc = '';
  protected $link = '';
  public function __construct(){
    $this->title = '物理学';
    $this->desc = '现代物理学';
    $this->link = 'http://mysql/rss.php';
    $this->dom = new DOMDocument('1.0','utf-8');
    $this->dom->load($this->temp);
    $this->rss = $this->dom->getElementsByTagName('rss')->item(0);
  }
  public function feed($arr){
    $this->createChannel();
    $channel = $this->dom->getElementsByTagName('channel')->item(0);
    foreach ($arr as $v){
      $channel->appendChild($this->createItem($v));
    }
    header('content-type:text/xml');
    echo $this->dom->savexml();
  }
  protected function createChannel(){
    $channel = $this->dom->createElement('channel');
    $channel->appendChild($this->createEle('title',$this->title));
    $channel->appendChild($this->createEle('link',$this->link));
    $channel->appendChild($this->createEle('description',$this->desc));
    $this->rss->appendChild($channel);
  }
  protected function createItem($arr){
    $item = $this->dom->createElement('item');
    foreach($arr as $k => $v){
      $item->appendChild($this->createEle($k,$v));
    }
    return $item;
  }
  protected function createEle($name,$value){
    $e=$this->dom->createElement($name);
    $t=$this->dom->createTextNode($value);
    $e->appendChild($t);
    return $e;
  }
}
$arr = array(
  array(
    'title'=>'牛顿力学',
    'link'=>'1',
    'description'=>'牛顿力学'
  ),
  array(
    'title'=>'相对论',
    'link'=>'1',
    'description'=>'爱因斯坦的相对论'
  )
);
$rss = new Rss;
$rss->feed($arr);
?>