Dynamic panel loading driven in serverside

I have a usecase(common) and I'm searching for right technology... Pls suggest..

Usecase: create dynamic panels based on user selection.

We have a drop down box where user can chose a value based on which I'll be loading some html components(can be text box,drodown,etc) in a div..some of these html components are common and some are specific to the value chosen in drop down..

Right now we have jsps , n lot of if-elses to determine whether to load the component or not...This has grown to an extent where maintenance takes a huge effort..

What I'm looking for:

Whether we can drive these panels in Java(serverside) with any technology or any other idea is appreciated..