How to handle response codes in RestTemplate without catching exceptions? [Spring Boot] - spring

Question

I'm sending a response to another web service to create an user. If the user already exists it sends back the 409 response. I'm using RestTemplate like so:
#PostMapping("/todos/{toDoNoteId}/users")
public ResponseEntity <String> postUser(#RequestBody User user, #PathVariable int toDoNoteId, UriComponentsBuilder builder)throws HttpMessageNotReadableException, ParseException{
RestTemplate restTemplate = new RestTemplate();
final String uri = "http://friend:5000/users";
try {
ResponseEntity<String> result = restTemplate.postForEntity(uri, user, String.class);
return result;
}
catch (HttpClientErrorException ex) {
return ResponseEntity.status(ex.getRawStatusCode()).headers(ex.getResponseHeaders())
.body(ex.getResponseBodyAsString());
}
}
While catching an exception somewhat works (in the catch block i can access the status code and body), is there a way to access it without exceptions something similar like this:
#PostMapping("/todos/{toDoNoteId}/users")
public ResponseEntity <String> postUser(#RequestBody User user, #PathVariable int toDoNoteId, UriComponentsBuilder builder)throws HttpMessageNotReadableException, ParseException{
RestTemplate restTemplate = new RestTemplate();
final String uri = "http://friend:5000/users";
ResponseEntity<String> result = restTemplate.postForEntity(uri, user, String.class);
if(result.getStatusCode()=="409"){
// do something
}
else{
// do something else
}
return result;
}

Answer 1

Have you been check the ExceptionHandler? When exception throws, ExceptionHandler handles it.
For example:
#ControllerAdvice()
public class CustomExceptionHandler {
private static final Logger logger = LogManager.getLogger("CustomExceptionHandler");
#ExceptionHandler(YourException.class)
public ResponseEntity handleYourException(HttpServletRequest request, YourException ex) {
return ResponseEntity.ok("");
}
#ExceptionHandler(Exception.class)
public ResponseEntity handleException(HttpServletRequest request, Exception ex) {
logExp("Exception", request, ex);
//return new ResponseEntity<>();
return null;
}
}

Answer 2

You can create your own custom resttemplate and define exception handler. Here is a code snippet.
#Configuration
public class CustomRestTemplate extends RestTemplate {
#Autowired
private CustomErrorHandler customErrorHandler;
#PostConstruct
public void init() {
this.setErrorHandler(customErrorHandler);
}
}
#Component
public class CustomErrorHandler implements ResponseErrorHandler {
#Override
public boolean hasError(ClientHttpResponse response) throws IOException {
if(response.getStatusCode() != "409"){
return true;
}else {
return false;
}
}
#Override
public void handleError(ClientHttpResponse response) throws IOException {
String responseBody = response.getBody();//Pls read from InputStream and create write into String
JSONObject jsonObj = new JSONObject(result);
JSONArray jsonArray = new JSONArray();
jsonObj.put("status", response.getStatusCode());
jsonObj.put("body", responseBody );
jsonArray.put(jsonObj);
responseString = jsonArray.get(0).toString();
throw new MyException(responseString );
}
}
class MyException throw RuntimeException {
public MyException (String message) {
super(message);
}
}
So, your class will changed to
#PostMapping("/todos/{toDoNoteId}/users")
public ResponseEntity <String> postUser(#RequestBody User user, #PathVariable int toDoNoteId, UriComponentsBuilder builder)throws HttpMessageNotReadableException, ParseException{
CustomRestTemplate restTemplate = new CustomRestTemplate ();
final String uri = "http://friend:5000/users";
ResponseEntity<String> result = restTemplate.postForEntity(uri, user, String.class);
return result
}