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。
functionrelative_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;
}
?>