Notes

@Controller
public class MyController {

@Autowired
private IDataService dataService;

@RequestMapping(value = "/getData")
public ModelAndView getData() {

var data = dataService.findAll();

Map<String, Object> params = new HashMap<>();
params.put("values", data);

return new ModelAndView("showData", params);
}

@ExceptionHandler(MyDataException.class)
public String handleError(MyDataException e) {

return "redirect:/showError.html";
}
}
The MyController's getData() method calls a service method and stores the retrieved data into a list. The data is sent to the showData view. In case of a MyDataException, the controller redirects to an error page.
The handleError() is decorated with @ExceptionHandler. The handler is activated for the MyDataException. In the body of the method, we redirect to the showError.html page.

While working on the REST API, we may need to bind the HTTP request and response body with the domain object. Spring @RequestBody and @ResponseBody annotations used to bind these HTTP request/response.
@RequestBody
Simply put, the @RequestBody annotation maps the HttpRequest body to a transfer or domain object, enabling automatic deserialization of the inbound HttpRequest body onto a Java object. Spring automatically deserializes the JSON into a Java type assuming an appropriate one is specified. By default, the type we annotate with the @RequestBody annotation must correspond to the JSON sent from our client-side controller.

@ResponseBody
The @ResponseBody annotation tells a controller that the object returned is automatically serialized into JSON and passed back into the HttpResponse object.