ClientHttpResponse.getBody() throws ResourceAccessException when response code is 401

Question

I am trying to log the request-response pairs for every request. The problem is that when the response code is 401, ClientHttpResponse.getBody() throws a ResourceAccessException and i cannot read the response body.

This is the RestTemplate configuration

RestTemplate restTemplate = new RestTemplate();

// Added this requestFactory to make response object readable more than once.
ClientHttpRequestFactory requestFactory =
        new BufferingClientHttpRequestFactory(new SimpleClientHttpRequestFactory());
restTemplate.setRequestFactory(requestFactory);
restTemplate.getInterceptors().add(new RequestLoggingInterceptor(vCloudRequest.getAction(),httpHeaders));
    restTemplate.setErrorHandler(new RequestErrorHandler());

return restTemplate;

The last line of the interceptor below throws the following exception.

How can i resolve this problem?

org.springframework.web.client.ResourceAccessException: I/O error on POST request for "https://example.com/api/sessions": Server returned HTTP response code: 401 for URL: https://example.com/api/sessions; nested exception is java.io.IOException: Server returned HTTP response code: 401 for URL: https://example.com.11/api/sessions

This is the related part of the interceptor.

@Override
public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
    ClientHttpResponse response = execution.execute(request, body);

    String requestString = new String(body);

    // Calling this method because when we make a POST or PUT request and get an error
    // response.getBody() throws IOException. But if we call response.getStatusCode() it works fine.
    // I don't know the reason.
    // I asked a question on stackoverflow
    // https://stackoverflow.com/questions/47429978/resttemplate-response-getbody-throws-exception-on-4-and-5-errors-for-put-and
    response.getStatusCode();
    String responseString = new String(ByteStreams.toByteArray(response.getBody()), Charset.forName("UTF-8"));
...
}

This is the custom error handler

public class RequestErrorHandler implements ResponseErrorHandler {

@Override
public boolean hasError(ClientHttpResponse response) throws IOException {
        if (!response.getStatusCode().is2xxSuccessful()) {
        return true;
    }
    return false;
}

@Override
public void handleError(ClientHttpResponse response) throws IOException {
    JAXBElement<ErrorType> root = null;

    try {
        JAXBContext jaxbContext = JAXBContext.newInstance(ErrorType.class);
        Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();

        root = jaxbUnmarshaller.unmarshal(new StreamSource(
                response.getBody()), ErrorType.class);
    } catch (JAXBException e) {
        throw new IOException("XML converting error. Cannot convert response to ErrorType");
    }

    ErrorType error = root.getValue();
    throw new VcloudException(error);
}
}

Answer 1

Use HttpComponentsClientHttpRequestFactory instead of SimpleClientHttpRequestFactory.

Also add dependency to 'org.apache.httpcomponents:httpclient.

HttpComponentsClientHttpRequestFactory ccan read body when status is 401.

Answer 2

I do not think, ResourceAccessException is being thrown by response.getBody(), instead seems to be that ByteStreams.toByteArray(...) is sending probably a null stream in response.

Can you please try debugging if response.getBody() is null or it's ByteStreams.toByteArray(). Because RescourceAccessException is thrown when an I/O error occurs.

Answer 3

Spring RestTemplate as default generates an error when httpstatus is not 200.

In my past project what I did is to add a custom org.springframework.web.client.ResponseErrorHandler to the rest template. You may wrote a class like this:

public class SimpleRestErrorHandler implements ResponseErrorHandler
{
    private static final Logger logger = LoggerFactory.getLogger(SimpleRestErrorHandler.class.getName());
    @Override
    public boolean hasError(ClientHttpResponse response) throws IOException
    {
        int statusCode = response.getStatusCode().value();
        if( logger.isDebugEnabled() )
        {

            logger.debug("STATUS CODE ["+statusCode+"] ");
        }
        //Generate Error only when HTTP Status code is 500
        if( statusCode == 500 )
        {

            return true;
        }
        return false;
    }

    @Override
    public void handleError(ClientHttpResponse response) throws IOException
    {
      //Here you can manage the error (in this sample only the http status code = 500
    }

}

Then I added this to my rest template:

XML configuration sample

<bean id="restTemplate" class="org.springframework.web.client.RestTemplate">        <constructor-arg ref="bufferingClientHttpRequestFactory" />         <property name="errorHandler" ref="simpleRestErrorHandler" />       <property name="messageConverters">             <list>
                <bean
                    class="org.springframework.http.converter.StringHttpMessageConverter">
                    <constructor-arg value="#{T(java.nio.charset.Charset).forName('UTF-8')}" />
                </bean>
                <bean
                    class="org.springframework.http.converter.ByteArrayHttpMessageConverter" />
                <bean
                    class="org.springframework.http.converter.ResourceHttpMessageConverter" />
                <bean
                    class="org.springframework.http.converter.xml.SourceHttpMessageConverter" />
                <bean
                    class="org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter" />
                <bean
                    class="org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter" />
                <bean
                    class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" />
                <bean
                    class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" />          </list>         </property>         <property name="interceptors">          <!-- Custom interceptors -->        </property>     </bean> <bean id="bufferingClientHttpRequestFactory" name="bufferingClientHttpRequestFactory"       class="org.springframework.http.client.BufferingClientHttpRequestFactory">      <constructor-arg ref="simpleReqFact" />     </bean> <bean id="simpleRestErrorHandler" class="handlers.SimpleRestErrorHandler" />

Java config

@Config
public class restTemplConfig {
 @Bean
 public RestTemplate restTempl() {
  RestTemplate result = new RestTemplate();
  //Add converters
  //Add custom error handler
  result.setErrorHandler(new SimpleRestErrorHandler());
 }
}

I hope it's useful