View logic in spring MVC

Spring MVC application with JPA

I have flow of my application like:

@Controller
Class 

---> returning a view (JSP) page.

Before returning to view I would like to modify contents or before sending it to entity persistence service layer , would like some values to be altered.Where shall I introduce those classes?

EDIT :

I am clear about rendering the data from database and displaying to front view. What I actually want to ask is like :

A a = aService.findXXX(aId);
//here i want some operations to be performed for specific view while converting it to dto and sending it to UI.

Where the class for doing the same would be introduced else my controller will have very large line of code sp. to what has to be displayed to sp. view?