Is there a Java library that can interact with a website?

So, I'm looking at this game called diep.io and I want to write a Java program that can play it automatically. However, I really don't know where to start. I want a Java library that can send keyboard inputs to the website diep.io, and some library that can detect things on the game screen. I've read some posts that talk about selenium or some urlconnection things, but those only seem to work with text inputs and getting info back from the server?

I feel like I don't even have the proper CS vocab to describe what I want to do. As you can see, I am a complete noob, but some pointers would be nice.

Thank you for your time!