spring rest Handling empty request body (400 Bad Request)

Question

I am developing a RESTful app using Spring4. I want to handle the case when a POST request contains no body. I wrote the following custom exception handler:

    @ControllerAdvice
    public class MyRestExceptionHandler {
     
      @ExceptionHandler
      @ResponseStatus(HttpStatus.BAD_REQUEST)
      public ResponseEntity<MyErrorResponse> handleJsonMappingException(JsonMappingException ex) {
          MyErrorResponse errorResponse = new MyErrorResponse("request has empty body");
          return new ResponseEntity<MyErrorResponse>(errorResponse, HttpStatus.BAD_REQUEST);
      }   
      @ExceptionHandler(Throwable.class)
      public ResponseEntity<MyErrorResponse> handleDefaultException(Throwable ex) {
        MyErrorResponse errorResponse = new MyErrorResponse(ex);
        return new ResponseEntity<MyErrorResponse>(errorResponse, HttpStatus.BAD_REQUEST);
      }
    }
    
     @RestController
     public class ContactRestController{
        @RequestMapping(path="/contact", method=RequestMethod.POST)
        public void save(@RequestBody ContactDTO contactDto) {...}
     } 

When it receives a POST with no body, these methods aren't called. Instead, the client gets a response with 400 BAD REQUEST HTTP status and empty body. Does anybody know how to handle it?

Answer 1

I solved the issue (the custom exception handler must extend ResponseEntityExceptionHandler). My solution follows:

        @ControllerAdvice
        public class RestExceptionHandler extends ResponseEntityExceptionHandler {
    
            @Override
            protected ResponseEntity<Object> handleHttpMessageNotReadable(
                HttpMessageNotReadableException ex, HttpHeaders headers,
                HttpStatus status, WebRequest request) {
                // paste custom hadling here
            }
        }