使用.htaccess文件重定向

This may sound like a questing that has been asked many times before but what I want to do is very specific. I want to redirect any requests to a "directory" to my root, e.g:

http://example.com/sub/12345.html -- restricts to --> http://example.com

http://example.com/sub/foobar.php -- redirects to --> http://example.com

http://exmpale.com/othersub/foo -- should not redirect!

The catch is that I don't want the URL to change, only the contents. So visitors should see the URL they enter in the address bar but the website index contents. My .htaccess file already contains a rewrite to handle what happens if the use emits the file type. I don't know if this would interfere with what I want to do but I'll provide it just for clarification.

Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^ %{REQUEST_URI}.php [L]

Thanks in advance!

You need a new rule to handle that rerrite:

Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /

RewriteRule ^sub/.+$ / [L,NC]

RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^ %{REQUEST_URI}.php [L]