Bill controller used to demonstrate how to access session object from validator

BillController.java

import org.springframework.web.servlet.mvc.SimpleFormController;

public class BillController extends SimpleFormController {

  private BillService billService;

  public BillController() {
    setValidator(new BillValidator());
  }

  @Override
  protected Map referenceData(HttpServletRequest request, Object command, Errors errors) throws Exception {
    Form form = (Form) command;
    Bill bill = billService.getBill(form.getId());
    BigDecimal paymentDue = bill.getPaymentDue(); // -1.19
    // Add payment due as attribute to session object
    request.getSession().setAttribute("paymentDue", paymentDue);
    Map<String,Object> map = new HashMap<String,Object>();
    // Populate JSP page with bill information, e.g. name, address, payment due, etc.
    map.put("bill", bill);
    return map;
  }

  @Override
  protected void onBind(HttpServletRequest request, Object command) throws Exception {
    ((BillValidator) getValidator()).setRequest(request);
  }

}