In case, if anyone prefers a simpler solution, especially on Linux (e.g. Ubuntu), a very easy way out is to create a symbolic link to the intended folder in the htdocs folder. For example, if I want to be able to serve files from a folder called "/home/some/projects/testserver/" and my htdocs is located in "/opt/lampp/htdocs/". Just create a symbolic link like so:
ln -s /home/some/projects/testserver /opt/lampp/htdocs/testserver
The command for symbolic link works like so:
ln -s target source
where,
target - The existing file/directory you would like to link TO.
source - The file/folder to be created, copying the contents of the target. The LINK itself.
For more help see ln --help Source: Create Symbolic Links in Ubuntu
And that's done. just visit http://localhost/testserver/ In fact, you don't even need to restart your server.