Converting relative URL to absolute

问题:

Let's say I have a URL of the document linking to another document (which can be both absolute or relative) and I need to have this link in absolute.

I made the simple function providing this functionality for several common cases:

function absolute_url($url,$parent_url){
  $parent_url=parse_url($parent_url);
  if(strcmp(substr($url,0,7),'http://')==0){
    return $url;
  }
  elseif(strcmp(substr($url,0,1),'/')==0){
    return $parent_url['scheme']."://".$parent_url['host'].$url;
  }
  else{
    $path=$parent_url['path'];
    $path=substr($path,0,strrpos($path,'/'));
    return $parent_url['scheme']."://".$parent_url['host']."$path/".$url;
  }
}

$parent_url='http://example.com/path/to/file/name.php?abc=abc';
echo absolute_url('name2.php',$parent_url)."\n";
// output http://example.com/path/to/file/name2.php
echo absolute_url('/name2.php',$parent_url)."\n";
// output http://example.com/name2.php
echo absolute_url('http://name2.php',$parent_url)."\n";
// output http://name2.php

The code works fine, but there could be more cases such as ../../path/to/file.php which will not work.

So is there any standard classes or function doing this thing better (more universal) that my function?

I tried to Google it and check the similar questions (one and two) but it looks like server-path related solution which is not the thing I'm looking for.

回答1:

This function will resolve relative URLs to a given current page url in $pgurl without regex. It successfully resolves:

/home.php?example types,

same-dir nextpage.php types,

../...../.../parentdir types,

full http://example.net urls,

and shorthand //example.net urls

//Current base URL (you can dynamically retrieve from $_SERVER)
$pgurl = 'http://example.com/scripts/php/absurl.php';

function absurl($url) {
 global $pgurl;
 if(strpos($url,'://')) return $url; //already absolute
 if(substr($url,0,2)=='//') return 'http:'.$url; //shorthand scheme
 if($url[0]=='/') return parse_url($pgurl,PHP_URL_SCHEME).'://'.parse_url($pgurl,PHP_URL_HOST).$url; //just add domain
 if(strpos($pgurl,'/',9)===false) $pgurl .= '/'; //add slash to domain if needed
 return substr($pgurl,0,strrpos($pgurl,'/')+1).$url; //for relative links, gets current directory and appends new filename
}

function nodots($path) { //Resolve dot dot slashes, no regex!
 $arr1 = explode('/',$path);
 $arr2 = array();
 foreach($arr1 as $seg) {
  switch($seg) {
   case '.':
    break;
   case '..':
    array_pop($arr2);
    break;
   case '...':
    array_pop($arr2); array_pop($arr2);
    break;
   case '....':
    array_pop($arr2); array_pop($arr2); array_pop($arr2);
    break;
   case '.....':
    array_pop($arr2); array_pop($arr2); array_pop($arr2); array_pop($arr2);
    break;
   default:
    $arr2[] = $seg;
  }
 }
 return implode('/',$arr2);
}

Usage Example:

echo nodots(absurl('../index.html'));

nodots() must be called after the URL is converted to absolute.

The dots function is kind of redundant, but is readable, fast, doesn't use regex's, and will resolve 99% of typical urls (if you want to be 100% sure, just extend the switch block to support 6+ dots, although I've never seen that many dots in a URL).

Hope this helps,

回答2:

$uri = "..";
$path = realpath($uri);
$root = realpath($_SERVER["DOCUMENT_ROOT"]);

if($path){
    $path = str_replace($root, "", $path);
    $path = $_SERVER["SERVER_NAME"] . $path;
    $protocol = "http";
    if(isset($_SERVER["HTTPS"])){
        $protocol .= "s";        
    }
    $path = "{$protocol}://$path";
    $path = str_replace("\\", "/", $path);
}

var_dump($path);

There is probably a better/quicker way, but I just knocked this up...