如何检查Resttemplate是否出错？

Question

How can I check if I get an error with RestTemplate in my SpringBootApplication properly? I managed to create an ResponseErrorHandler but am not sure how to handle that error in my code. So I want to print an error message if an error occured and else process the response if everything is ok. How can I do that?

ErrorHandler:

public class MyErrorHandler implements ResponseErrorHandler {
    private boolean error;
    @Override
    public void handleError(ClientHttpResponse response) throws IOException {
        error = false;
        if(response.getStatusCode() == HttpStatus.FAILED_DEPENDENCY) {
            error = true;
            JOptionPane.showMessageDialog(null, "Error " + response.getStatusCode() + ": " /*Can I print my errormessage here?*/);
        }
    }

    @Override
    public boolean hasError(ClientHttpResponse response) throws IOException {
        return error;
    }

Getting Data:

HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.TEXT_PLAIN);
        headers.add("Accept", MediaType.TEXT_PLAIN_VALUE);
        HttpEntity<String> httpRequest = new HttpEntity<String>(request, headers);

        RestTemplate restTemplate = new RestTemplate();
        restTemplate.setErrorHandler(new MyErrorHandler());
        restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
        restTemplate.getMessageConverters().add(new StringHttpMessageConverter());

        String response = (String) restTemplate.postForObject("http://127.0.0.1:8081/post", httpRequest, String.class);

        /*If error occured, print errormessage, else do something*/

Server:

@PostMapping("/post")
    ResponseEntity add(@RequestBody String string) {

        if(acceptServerRequest)
            return ResponseEntity.ok("Post recieved: " + string);
        else
            return new ResponseEntity("Error!", HttpStatus.FAILED_DEPENDENCY);
    }

Answer 1

Instead of doing like this

 String response = (String) restTemplate.postForObject("http://127.0.0.1:8081/post", httpRequest, String.class);

You can do like this

ResponseEntity<String> response = (String) restTemplate.postForEntity("http://127.0.0.1:8081/post", httpRequest, String.class);

With this response object you can get status doing response.getStatus() which retuns an object of type HttpStatus which has various utility methods like

is2xxSuccessful()
is4xxClientError()  

Which can be used to get the status's in general