Spring RestTemplate：在配置类中设置时覆盖ResponseErrorHandler不起作用

Question

I have the RestTemplate where l am overridding the ResponseErrorHandler like in the code below

@Bean
public RestTemplate restTemplate() {
    RestTemplate restTemplate = new RestTemplate(new BufferingClientHttpRequestFactory(new SimpleClientHttpRequestFactory()));
    restTemplate.setErrorHandler(new RsponseError());
    return restTemplate;
}

and my ResponseError class is like this

public class RsponseError implements ResponseErrorHandler{

@Override
public boolean hasError(ClientHttpResponse clientHttpResponse) throws IOException {
    log.info("statuscode {}",clientHttpResponse.getStatusCode());
    return true;
}

@Override
public void handleError(ClientHttpResponse clientHttpResponse) throws IOException {

    log.info("status code {}",clientHttpResponse.getStatusCode());
    log.info("status text {}",clientHttpResponse.getStatusText());

}

If l autowire the RestTemplate and invoke a rest service and an error is generated the ResponseError does not work. But if l do not set the error handler in the Configuration and set it after autowiring the RestTemplate like below class it will work.

@Autowired
private RestTemplate restTemplate;


@Override
public ResponseEntity<ClassExampleResponse> invoker(ClassExample classExample,
                                                                String uri) throws Exception {
        final RequestEntity<ClassExample> requestEntity = new RequestEntity<>(classExample, requestHeader(), HttpMethod.POST, new URI("https://somelink"));
        restTemplate.setErrorHandler(new RsponseError());
        final ResponseEntity<ClassExampleResponse> responseEntity = restTemplate.exchange(requestEntity, ClassExampleResponse.class);
    return responseEntity;
}

Why is it that restTemplate.setErrorHandler(new RsponseError()); is not working when set in configuration class?. Thanks for you help in advance.

Answer 1

You can use @ControllerAdvice to make all your problems disappear!

Here is a short example, which should solves your issue. It take the output from your bean validation and display it as JSON.

You can take a look at one of my previous answers. This will cover some of the details how this works. Bean validation in DropWizard with custom Json output

@ExceptionHandler(MethodArgumentNotValidException.class)
@Order(1)
public ResponseEntity<ValidationErrors> handleUnexpectedException(MethodArgumentNotValidException errors) {

    ValidationErrors validationErrors = new ValidationErrors();

    for (FieldError fe : errors.getBindingResult().getFieldErrors()) {

        String field = fe.getField();
        String msg = fe.getDefaultMessage();

        validationErrors.add(field, msg);
    }
    return new ResponseEntity<ValidationErrors>(validationErrors, HttpStatus.UNPROCESSABLE_ENTITY);
}

public class ValidationErrors {

    public List<ValidationObject> errors = new ArrayList<ValidationObject>();

    public void add(String field, String error){
        errors.add(new ValidationObject(field, error));
    }
}


public class ValidationObject {

    private String field, error;

    public ValidationObject(String field, String error){
        this.field = field;
        this.error = error;
    }

    public String getField() {
        return field;
    }

    public void setField(String field) {
        this.field = field;
    }

    public String getError() {
        return error;
    }

    public void setError(String error) {
        this.error = error;
    }
}

Answer 2

I believe the ErrorHandler of your RestTemplate bean is set from other places after RestTemplate bean is generated so that you have to override the ErrorHandler forcely when calling the resttemplate.

Please check all the places autowiring the RestTemplate and see if restTemplate. setErrorHandler() is called.