PHP如何打开page1,重定向到page2并在div dom中显示page1?

I have many sub pages, there urls like www.domain.com/sub/page1.php www.domain.com/sub/page2.php... Now when I type there url in browser. they all redirect to www.domain.com/sub/index.php, and the current sub page will show in a div dom in the index.php.

My knowledge is very limited. I only know jqeury.load and php header Location. but it is difficult redirect to index.php then tell index.php, which is the current sub-pages then do a jqeury.load.

One more note: Also should think SEO. maybe jqeury.load is bad for a search spider. maybe should use hash url.

So I ask for a help. is there anybody could give me some good suggestion? or simple worked examples?

Thanks.

In every PHP file (e.g page1.php) use this code:

<?php
if(!defined('INCLUDE')) {
    header('Location: index.php?site=' . $_SERVER['PHP_SELF']); //Send the user to the index.php page
    die();
}
?>
Insert the content you want here...

And in the index.php file:

<?php
define('INCLUDE', true);
if(isset($_GET['site'])) {
    $site = $_GET['site'];
} else {
    $site = 'page100.php'; //Put the name of the default page if the user visits index.php here
}
?>
<html>
<head><!-- HEAD CONTENT HERE --></head>
<body>
<div><?php 
include($site); //Put the page requested into the div
?></div>
</body>
</html>