php相对路径转化成绝对路径

  提取 Gregarius中的一个函数。可以把网页中的相对路径自动转化成绝对路径。
  <?
  function relative_to_absolute($content, $feed_url) {
   preg_match('/(http|https|ftp):\/\//', $feed_url, $protocol);
   $server_url = preg_replace("/(http|https|ftp|news):\/\//", "", $feed_url);
   $server_url = preg_replace("/\/.*/", "", $server_url);
   if ($server_url == '') {
   return $content;
   }
   if (isset($protocol[0])) {
   $new_content = preg_replace('/href="\//', 'href="'.$protocol[0].$server_url.'/', $content);
   $new_content = preg_replace('/src="\//', 'src="'.$protocol[0].$server_url.'/', $new_content);
   } else {
   $new_content = $content;
   }
   return $new_content;
  }
  ?>