The following interceptor does the trick for us. It determines, if to redirect or not by looking at the view name. If so, it saves the model and the view name without the prefix into the HttpSession. Then it constructs a redirect url with the id of the saved model.
The same interceptor is used to reconstruct the model by looking at the request parameters.
The only caveat is, that lazy-loading doesn't work for the saved model, because a new request has started and the hibernate session the objects in the model point to is already closed.
The only even more transparent way I can imagine is to use a ServletFilter that saves the generated response to the session and outputs a redirect instead. After the redirect has happend, the previously saved response is sent to the browser. That should solve all Spring MVC problems with redirect-after post.
The code
import java.rmi.server.UID;
import java.util.Date;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.ModelAndViewDefini ngException;
import org.springframework.web.servlet.handler.HandlerInt erceptorAdapter;
import org.springframework.web.servlet.view.RedirectView;
public class RedirectInterceptor extends HandlerInterceptorAdapter
{
private String viewPrefix;
private String sessionAttributePrefix;
private String requestParameterName;
private static class RedirectInfo
{
long timestamp;
ModelAndView modelAndView;
}
public boolean preHandle(
HttpServletRequest request,
HttpServletResponse response,
Object handler)
throws Exception
{
// Are we coming from a redirect?
if ("GET".equals(request.getMethod()) && request.getParameter(requestParameterName)!= null)
{
// reconstruct name of the RedirectInfo-Object
String attributeName=sessionAttributePrefix+request.getPa rameter(requestParameterName);
HttpSession session=request.getSession(false);
// go to the originally wanted view
RedirectInfo info=null;
if (session != null && session.getAttribute(attributeName) != null)
{
info = (RedirectInfo) session.getAttribute(attributeName);
session.removeAttribute(attributeName);
throw new ModelAndViewDefiningException(info.modelAndView);
}
}
return true;
}
public void postHandle(
HttpServletRequest request,
HttpServletResponse response,
Object handler,
ModelAndView modelAndView)
throws Exception
{
// Do we want to redirect?
String viewName=getActualViewName(request, modelAndView);
if (viewName != null)
{
// remember the model and the view and put it into the session
ModelAndView sessionMAV=new ModelAndView(viewName, modelAndView.getModel());
String id=getNewId();
String attributeName=sessionAttributePrefix+id;
RedirectInfo info=new RedirectInfo();
info.timestamp=new Date().getTime();
info.modelAndView=sessionMAV;
HttpSession session=request.getSession();
session.setAttribute(attributeName, info);
// modify model and view in order to let a redirect happen
modelAndView.clear();
RedirectView rv= new RedirectView(getOwnUrl(request));
modelAndView.setView(rv);
modelAndView.getModel().put(requestParameterName,i d);
}
}
// Returns null, if no redirect should happen, otherwise the view name without prefix
private String getActualViewName(HttpServletRequest request, ModelAndView modelAndView)
{
String viewName=null;
// POST and prefix trigger a redirect
if ("POST".equals(request.getMethod()))
{
if (modelAndView != null &&
modelAndView.getViewName() != null &&
modelAndView.getViewName().startsWith(viewPrefix))
{
viewName=modelAndView.getViewName();
viewName=viewName.substring(viewPrefix.length());
}
}
return viewName;
}
private String getNewId()
{
return new UID().toString();
}
private String getOwnUrl(HttpServletRequest request)
{
String url=request.getServletPath();
if(request.getPathInfo() != null)
{
url+=request.getPathInfo();
}
url=url.substring(url.lastIndexOf('/')+1);
return url;
}
public void setRequestParameterName(String string)
{
requestParameterName = string;
}
public void setSessionAttributePrefix(String string)
{
sessionAttributePrefix = string;
}
public void setViewPrefix(String string)
{
viewPrefix = string;
}
}
How to configure it:
<bean id="redirectInterceptor" class="RedirectInterceptor">
<property name="viewPrefix" value="RAP:"/>
<property name="sessionAttributePrefix" value="RAP"/>
<property name="requestParameterName" value="RAP"/>
</bean>
How to use it in a controller:
<property name="successView" value="RAP:yourview"/>
HTH
Fokko