使用PHP获取脚本的绝对URL？

Basically, I want my script to output its absolute URL, but I don't want to statically program it into the script. For example, if my current URL is http://example.com/script.php I want to be able to store it as a variable, or echo it. i.e. $url = http://example.com/script.php;

But if I move the script to a different server/domain, I want it to automatically adjust to that, i.e. $url = http://example2.com/newscript.php;

But I have no idea how to go about doing this. Any ideas?

$url = "http://" . $_SERVER['HTTP_HOST'] . '/script.php';

If there's a possibility the protocol will change as well (i.e. https instead of http), use this:

$url = ($_SERVER['HTTPS'] ? "https://" : "http://") . $_SERVER['HTTP_HOST'] . '/script.php';

$_SERVER['HTTP_HOST'] and $_SERVER['SCRIPT_NAME'] contain this information.

UPDATE: As @Col. Shrapnel points out, SCRIPT_NAME returns the actual path of the script relative to the host, not the requested URL, which may be different if using URL rewrite. Also, unlike REQUEST_URI, it doesn't include the possibly appended variables.

Note that SCRIPT_NAME is equivalent in content to PHP_SELF, the difference is that:

SCRIPT_NAME is defined in the CGI 1.1 specification, and is thus a standard. However, not all web servers actually implement it, and thus it isn't necessarily portable. PHP_SELF, on the other hand, is implemented directly by PHP, and as long as you're programming in PHP, will always be present.

Try using

$url = "http://{$_SERVER['SERVER_NAME']}{$_SERVER['REQUEST_URI']}";

by bet (:

$_SERVER['HTTP_HOST'] and $_SERVER["REQUEST_URI"];

however, $_SERVER['HTTP_PORT'] and $_SERVER['HTTPS'] could be used in the critical case

however, most of time you do not need all of these, save for $_SERVER["REQUEST_URI"]
because browser knows the rest already: port, host and everything.

I have a library that helps me do this across webservers and is also agnostic to mod_rewrite.

The library is called Bombay: http://github.com/sandeepshetty/bombay

To use it you need to do this:

<?php

    require '/path/to/bombay.php';
    requires ('uri');

    echo absolute_uri('script.php');

    //prints http://example.com/script.php if hosted on example.com and accessed over http
    //prints https://example2.com/script.php if hosted on example2.com and accessed over https

?>

You could also study the code, and take what you need.