Trigger 404 in Spring-MVC controller?

Rewrite your method signature so that it accepts HttpServletResponse as a parameter, so that you can call setStatus(int) on it.

http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-ann-requestmapping-arguments

Since Spring 3.0 you also can throw an Exception declared with @ResponseStatus annotation:

@ResponseStatus(value = HttpStatus.NOT_FOUND)
public class ResourceNotFoundException extends RuntimeException {
    ...
}

@Controller
public class SomeController {
    @RequestMapping.....
    public void handleCall() {
        if (isFound()) {
            // whatever
        }
        else {
            throw new ResourceNotFoundException(); 
        }
    }
}

Starting from Spring 5.0, you don't necessarily need to create additional exceptions:

throw new ResponseStatusException(NOT_FOUND, "Unable to find resource");

Also, you can cover multiple scenarios with one, built-in exception and you have more control.

See more:

• ResponseStatusException (javadoc)
• https://www.baeldung.com/spring-response-status-exception

Since Spring 3.0.2 you can return ResponseEntity<T> as a result of the controller's method:

@RequestMapping.....
public ResponseEntity<Object> handleCall() {
    if (isFound()) {
        // do what you want
        return new ResponseEntity<>(HttpStatus.OK);
    }
    else {
        return new ResponseEntity<>(HttpStatus.NOT_FOUND);
    }
}

(ResponseEntity<T> is a more flexible than @ResponseBody annotation - see another question)