一个我经常用到的采集网页数据抓取网页获取数据的PHP函数类

class get_c_str {  
var $str;  
var $start_str;  
var $end_str;  
var $start_pos;  
var $end_pos;  
var $c_str_l;  
var $contents;  
function get_str($str,$start_str,$end_str){  
   $this->str = $str;  
   $this->start_str = $start_str;  
   $this->end_str = $end_str;  
   $this->start_pos = strpos($this->str,$this->start_str)+strlen($this->start_str);  
     $this->end_pos = strpos($this->str,$this->end_str);  
   $this->c_str_l = $this->end_pos - $this->start_pos;  
   $this->contents = substr($this->str,$this->start_pos,$this->c_str_l);  
   return $this->contents;  
}  
}
//使用方法
$url = 'http://www.xiaodoubi.com';
$data = file_get_contents($url);
$get_c_str = new get_c_str;
$content = $get_c_str -> get_str($data,'<p class="message">','</p>');
echo $content;