Return JSON on uncaught exceptions in Spring controllers

For returning JSON on uncaught exceptions you can use this code:

import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.RestController;@ControllerAdvice  @RestControllerpublic class GlobalExceptionHandler {    private class JsonResponse {        String message;        public JsonResponse() {        }        public JsonResponse(String message) {            super();            this.message = message;        }        public String getMessage() {            return message;        }        public void setMessage(String message) {            this.message = message;        }           }    @ExceptionHandler(value = Exception.class)      public ResponseEntity<JsonResponse> handleException(Exception e) {        return new ResponseEntity<JsonResponse>(new JsonResponse(e.getMessage()), HttpStatus.BAD_REQUEST);    }}

JSON result if exception is throwing:

{    "message": "Something wrong!"}

You can use this link for more detailed information about Spring exception handling (with code examples).

HttpEntity represents an HTTP request or response consists of headers and body.

// Only talks about body & headers, but doesn't talk about status codepublic HttpEntity(T body, MultiValueMap<String,String> headers)

ResponseEntity extends HttpEntity but also adds a Http status code.

// i.e ResponseEntity = HttpEntity + StatusCodepublic ResponseEntity(T body, MultiValueMap<String,String> headers, HttpStatus statusCode)

Hence used to fully configure the HTTP response.

If you have a look at constructor of ResponseEntity you will see first parameter as body, i.e exactly where you can pass the object you want as body of http response when exception arrives