RESTful Webservice Using Spring Framework - spring

Question

I have written some RESTful webservices using Spring Framework (by reading posts online / video tutorials etc.) , however I still have some doubts.
When we write a web-application using Spring MVC module we use controller code, similar to below:
#Controller
public class SimpleController {
#RequestMapping("/welcome")
ModelAndView handleIncomingWelcomeReq() {
ModelAndView mw = new ModelAndView("WelcomePage","welcomeKey","WelcomeKey's value!");
return mw;
}
}
In the above code there is ModelAndView object which this controller returns, and this can be invoked like this URL:
http://localhost:8080/contextRoot/welcome
Now, if we exclude the "view" part and return just the model doesn't it act like a web service?
So my doubt is, in Spring do we used the same API/jar's to create web-application or RESTful web services?
The things which I read is that for Spring REST support, it has annotation #RestController annotation (which itself is like #Contoller + #ResponseBody annotations).
So what is the difference in which the implementation of REST WS and web-applications differs in Spring Framework?
Can anyone help me understand this?

Answer 1

Yes we can write RestService & web application using Spring. Use #RestController to expose a REST service and #Controller for web application.
#RestController is a meta-annotation with #Controller and #ResponseBody. #Controller will search through the registered ViewResolvers, whereas #RestController will not.

Answer 2

#Controller
public class SimpleController {
#RequestMapping("/welcome", method = RequestMethod.GET, produces="application/json")
public #ResponseBody JSONObject handleIncomingWelcomeReq() {
JSONObject j = new JSONObject();
j.put("welcomeKey", "WelcocmeKey's value!");
return j;
}
Here is the code which returns response in json mostly user id Rest Apis.

Answer 3

I would suggest to use #Controller instead of #RestController, as #RestController, won't scan your views. So, in case if your application has it's own views and also needs to expose it's services, you can use #Controller along with the #ResponseBody annotations, with output as JSON.
Another option is to have completely different URL for RESTful webservices, where a different controller will handle the request. These different controllers can be annotated with #RestController.