Render multiple views within a single request - json

Question

I'm trying to return multiple views within a single request, returning them all in a JSON string.
Example:
#RequestMapping(value = "my-request")
public void myRequest(HttpServletRequest request, HttpServletResponse response) throws Exception
{
Map<String,Object> model1 = new Hashtable<String,Object>();
model1.put(...);
ModelAndView modelAndView1 = new ModelAndView("path/to/view1", model1);
// Render modelAndView1 in some way, in order to obtain the rendered HTML as a String
Map<String,Object> model2 = new Hashtable<String,Object>();
model2.put(...);
ModelAndView modelAndView2 = new ModelAndView("path/to/view2", model2);
// Render modelAndView2 in some way, in order to obtain the rendered HTML as a String
// Now write a JSON String to the HttpServletResponse containing both the rendered views (strings).
// (this is not part of my problem, I'm able to do it as long as I have the two strings)
}
I'm using Spring MVC with Tiles 2.
Can anyone help me?
Update 1 - View names are resolved using a ViewResolver:
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/tiles/" />
<property name="suffix" value=".jsp" />
</bean>
Update 2 - I've created a github repository containing a very small example reproducing the problem.

Answer 1

UPDATE: There are some approaches for solving your issue. I'd try this one, but maybe there are cleaner ways.
#Component
public class JsonMultipleViewFactory {
#Autowired private List<ViewResolver> viewResolverList;
public View getView(List<ModelAndView> mavList) {
for (ModelAndView mav : mavList) {
if (mav.getView()==null) {
mav.setView(resolve(mav.getViewName()));
}
}
return new JsonMultipleView(mavList);
}
private View resolve(String viewName) {
for (ViewResolver vr : viewResolverList) {
View view = vr.resolve(viewName, LocaleContextHolder.getLocale());
if (view!=null) {
return view;
}
}
return null;
}
}
public class JsonMultipleView implements View {
private final List<ModelAndView> mavList;
public JsonMultipleView(List<ModelAndView> mavList) {
this.mavList = mavList;
}
public String getContentType() {
return "application/json";
}
public void render(Map<String,?> model, HttpServletRequest request, HttpServletResponse response) {
Json json = new Json(); // You can use several Json libraries here
for (ModelAndView mav : mavList) {
MockHttpServletResponse mockResponse = new MockHttpServletResponse();
mav.getView().render(mav.getModel(), request, mockResponse);
json.add(mav.getViewName(), mockResponse.getContentAsString());
}
json.write(response.getOutputStream());
response.getOutputStream().close();
}
}
And can be used like this:
#Autowired private JsonMultipleViewFactory jsonMultipleViewFactory;
#RequestMapping(value = "my-request")
public View myRequest() {
...
List<ModelAndView> mavList = new ArrayList<ModelAndView>();
mavList.add(modelAndView1);
mavList.add(modelAndView2);
return jsonMultipleViewFactory.getView(mavList);
}