Give access to JSP file/folder only for particular IP address

I made a CMS application using JSP and servlet. I am not using any kind of framework. The CMS has 2 parts:

1. Front end
2. Admin (Back end)

If I hosted it on www.example.com, for example, then all my frond end site will show for all users.

But www.example.com/admin must be accessible from a couple of IP addresses. Not from all the users.

I found these links:

• link 1
• link 2
• Stack Overflow link

Link 1 looks bit confusing and Link 2 looks good, but I am not using JBoss.

In the Stack Overflow link they did not mention how to use it.