How to do a redirect in Spring MVC controller? - spring

Question

I am trying use a PRG (Post-Redirect-Get) pattern in one of my Spring MVC controller. The controller collects user data from an HTML form, does some processing, stores data in DB and then shows a JSP page. After saving data a redirect should happen and then the JSP page should be displayed.
I also tried to prepend "redirect:" in front of the VIEW_NAME but I get 404 then.
Please guide.
CartPageController.java
#Controller
#RequestMapping("/cartPageController.do")
public class CartPageController {
private static final Logger LOG = Logger.getLogger(CartPageController.class);
private static final String VIEW_NAME = "cart";
#Autowired
protected MasterDao masterDao;
#RequestMapping(method = {RequestMethod.GET, RequestMethod.POST})
public ModelAndView processRequest(HttpServletRequest request, HttpServletResponse response) {
LOG.debug("Into the CartPageController...");
HttpSession session = request.getSession();
ModelAndView mav = new ModelAndView();
//create Cart object and store it in session
Cart cart = null;
if (session.getAttribute("cart") != null) {
cart = (Cart) session.getAttribute("cart");
} else {
cart = createCart();
session.setAttribute("cart", cart);
}
LOG.debug("cart = " + cart);
//determine the cart operation
String btnAddToCart = GenericUtils.nullToEmptyString(request.getParameter("btnAddToCart"));
String removeProduct = GenericUtils.nullToEmptyString(request.getParameter("removeProduct"));
String updateProduct = GenericUtils.nullToEmptyString(request.getParameter("updateProduct"));
LOG.debug("btnAddToCart = " + btnAddToCart);
LOG.debug("removeProduct = " + removeProduct);
LOG.debug("updateProduct = " + updateProduct);
if (btnAddToCart.length() > 0) {
addToCart(request, cart);
} else if (removeProduct.length() > 0) {
removeProduct(request, cart);
} else if (updateProduct.length() > 0) {
updateCart(request, cart);
}
//TODO: Should use PRG pattern here
//TRIED TO APPEND "redirect:" here but does not work, gives me 404
mav.setViewName(VIEW_NAME);
return mav;
}
//some more code below here
}

Answer 1

You should redirect to url not a view name. as Spring doc says:
While
the use of RedirectView works fine, if the controller itself creates
the RedirectView, there is no avoiding the fact that the controller is
aware that a redirection is happening. This is really suboptimal and
couples things too tightly. The controller should not really care
about how the response gets handled. In general it should operate only
in terms of view names that have been injected into it.
The special redirect: prefix allows you to accomplish this. If a view
name is returned that has the prefix redirect:, the
UrlBasedViewResolver (and all subclasses) will recognize this as a
special indication that a redirect is needed. The rest of the view
name will be treated as the redirect URL.

Answer 2

you can try
return new ModelAndView(new RedirectView("/page"));

Answer 3

You can't just prepend "redirect:" to your view name which results in redirect:cart and then obviously 404, what you have to do for redirect is to specify the redirect path for e.g.:
redirect:/cart.htm
This should explain it more in details.

Answer 4

You can do this way
redirect:cart.do and have requestmapping in controller which will return cart view.
Hope this will work.