Validating request parameter before controller

I want to validate the request parameter which is just a string value. Most of the examples on the net talks about validating a domain object with custom validator. But I want to write a validator just for String value. How to achieve that?

@Controller
@RequestMapping("/base")
class MyController{

   //value needs to be validated.
   @RequestMapping("/sub")
   public String someMethod(@RequestParam String value, BindingResult result){
       if(result.hasErrors()){
          return "error";
       }

       //do operation
       return "view";

   }
}