php实现的一个很好用HTML解析器类可用于采集数据

<?php  
 $oldsetting = libxml_use_internal_errors( true );   
libxml_clear_errors();  
/**
 * 
 * -+-----------------------------------
 * |php5 framework - 2011
 * |web site: www.iblue.cc
 * |e-mail: mejinke@gmail.com
 * |date: 2012-10-12
 * -+-----------------------------------
 * 
 * @desc html解析器
 * @author jingke
 */   
class xf_htmldom  
{  
    private $_xpath = null;  
    private $_nodepath = '';  

    public function __construct($xpath = null, $nodepath = '')  
    {  
        $this->_xpath = $xpath;  
        $this->_nodepath = $nodepath;  
    }  

    public function loadhtml($url)  
    {  
        ini_set('user_agent', 'mozilla/5.0 (linux; u; android 2.1; en-us; nexus one build/erd62) applewebkit/530.17 (khtml, like gecko) version/4.0 mobile safari/530.17 –nexus');  
        $content = '';  
        if(strpos(strtolower($url), 'http')===false)  
        {  
            $content = file_get_contents($url);  
        }  
        else 
        {  
            $ch = curl_init();   
            $user_agent = "baiduspider+(+http://www.baidu.com/search/spider.htm)";  
            $user_agent1='mozilla/5.0 (windows nt 5.1; rv:6.0) gecko/20100101 firefox/6.0';  
            curl_setopt($ch, curlopt_url, $url);   
            curl_setopt($ch, curlopt_header, false);   
            curl_setopt($ch, curlopt_returntransfer, 1);   
            curl_setopt($ch, curlopt_referer, $url);  
            curl_setopt($ch, curlopt_useragent, $user_agent1);  
            curl_setopt($ch, curlopt_followlocation,1);  
            $content =curl_exec($ch);   
            curl_close($ch);  
        }  

        $html = new domdocument();   
        $html->loadhtml($content);   
        $this->_xpath = new domxpath( $html );   
        //return $this; 

    }  

    public function find($query, $index = null)  
    {  
        if($this->_nodepath == '')  
            $this->_nodepath = '//'; 
        else 
            $this->_nodepath .= '/';  

        $nodes = $this->_xpath->query($this->_nodepath.$query);  
        //echo $nodes->item(0)->getnodepath();exit; 

          
        if ($index == null && !is_numeric($index))   
        {   
            $tmp = array();  
            foreach ($nodes as $node)   
            {  
                $tmp[] = new xf_htmldom($this->_xpath, $node->getnodepath());  
            }  
            return $tmp;  
        }  
        return new xf_htmldom($this->_xpath,$this->_xpath->query($this->_nodepath.$query)->item($index)->getnodepath());  
    }  

    /**
     * 获取内容
     */ 
    public function text()  
    {  
        if ($this->_nodepath != '' && $this->_xpath != null )   
            return $this->_xpath->query($this->_nodepath)->item(0)->textcontent;  
        else 
            return false;  
    }  

    /**
     * 获取属性值
     */ 
    public function getattribute($name)  
    {  
        if ($this->_nodepath != '' && $this->_xpath != null )   
            return $this->_xpath->query($this->_nodepath)->item(0)->getattribute($name);  
        else 
            return false;  
    }  

    public function __get($name)  
    {  
        if($name == 'innertext')  
            return $this->text();  
        else 
            return $this->getattribute($name);  
    }    
}    
$xp = new xf_htmldom();  
$xp->loadhtml('http://www.aizhan.com/siteall/www.opendir.cn/'); 
$rows = $xp->find("td[@id='baidu']/a", 0)->innertext;  
print_r($rows);