使用Spring RestTemplate，出现错误时如何记录响应？

Question

Spring RestTemplate could set the errorHandler, which has the methods for handling errors. I have an error handler like this

try (BufferedReader buffer = new BufferedReader(new InputStreamReader(clientHttpResponse.getBody()))) {
     final String response = buffer.lines().collect(Collectors.joining("\n"));
     System.out.println(response);
  }

but it always tell me that the input stream is close. Is this a bug or do I missing something?

Answer 1

The default error handler of RestTemplate DefaultResponseErrorHandler already reads the response body and sets it in the HttpStatusCodeException object that it throws.

try {
    restTemplate.getForObject("http://...", String.class);
} catch (HttpStatusCodeException e) {
    System.out.println("Received error: " + e.getResponseBodyAsString());
}

If you want to always log the response body on error without requiring to catch HttpStatusCodeException , you can extend the default error handler.

public static class LoggingErrorHandler extends DefaultResponseErrorHandler {
    @Override
    public void handleError(ClientHttpResponse response) throws IOException {
        try {
            super.handleError(response);
        } catch (HttpStatusCodeException e) {
            System.out.println("Error response body is " + e.getResponseBodyAsString());
            throw e;
        }
    }
}

Use the above error handler while instantiating rest template.

RestTemplate restTemplate = new RestTemplate();
restTemplate.setErrorHandler(new LoggingErrorHandler());
String response = restTemplate.getForObject("http://...", String.class);