Log your RestTemplate Request and Response without destroying the body

When you’re working with REST services, it can be very useful for debugging to be able to log both the request and the response info. Fortunately, if you’re using the Spring framework’s RestTemplate its fairly easy to add an interceptor to do just that.

First let’s create our logger

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpRequest;
import org.springframework.http.client.ClientHttpRequestExecution;
import org.springframework.http.client.ClientHttpRequestInterceptor;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.util.StreamUtils;
 
import java.io.IOException;
import java.nio.charset.Charset;
 
public class RequestResponseLoggingInterceptor implements ClientHttpRequestInterceptor {
 
    private final Logger log = LoggerFactory.getLogger(this.getClass());
 
    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
        logRequest(request, body);
        ClientHttpResponse response = execution.execute(request, body);
        logResponse(response);
        return response;
    }
 
    private void logRequest(HttpRequest request, byte[] body) throws IOException {
        if (log.isDebugEnabled()) {
            log.debug("===========================request begin================================================");
            log.debug("URI         : {}", request.getURI());
            log.debug("Method      : {}", request.getMethod());
            log.debug("Headers     : {}", request.getHeaders());
            log.debug("Request body: {}", new String(body, "UTF-8"));
            log.debug("==========================request end================================================");
        }
    }
 
    private void logResponse(ClientHttpResponse response) throws IOException {
        if (log.isDebugEnabled()) {
            log.debug("============================response begin==========================================");
            log.debug("Status code  : {}", response.getStatusCode());
            log.debug("Status text  : {}", response.getStatusText());
            log.debug("Headers      : {}", response.getHeaders());
            log.debug("Response body: {}", StreamUtils.copyToString(response.getBody(), Charset.defaultCharset()));
            log.debug("=======================response end=================================================");
        }
    }
}

Now we simply to add it to our interceptor.

 
RestTemplate restTemplate = new RestTemplate();
 
restTemplate.setInterceptors(Collections.singletonList(new RequestResponseLoggingInterceptor()));
 
// use you restTemplate to make your REST call(s)

At this point there is one gotcha. The response body is a stream and if you read it in your interceptor it won’t be available for RestTemplate to deserialize it into your object model. In other words, when you call restTemplate.get… you’ll always get back empty objects (even as you see the object in your response. Fortunately you can fix that by using a BufferingClientHttpRequestFactory.

 
ClientHttpRequestFactory factory = new BufferingClientHttpRequestFactory(new SimpleClientHttpRequestFactory());
 
RestTemplate restTemplate = new RestTemplate(factory);
 
restTemplate.setInterceptors(Collections.singletonList(new RequestResponseLoggingInterceptor()));
 
// use you restTemplate to make your REST call(s)

Also published on Medium.

One thought on “Log your RestTemplate Request and Response without destroying the body

  1. Jan Kowalski says:

    This solution is wrong. Please consider empty json object in response (“{}”).

    1. jose says:

      This solution has nothing to do with JSON.

  2. Nathanael Shergold says:

    Thanks for posting this, it has been helpful for debugging. I was going to say there’s a bit of a gotcha with the InputStream not being reset but as usual having just skimmed I missed your excellent fix for that as well.

    Nathanael Shergold
    Seventy-Nine Consulting
    https://79sconsulting.com.au

  3. Mr Developer says:

    Hi, nice solution however doesn’t work when using mockServer to test the server.

    1. John says:

      Would be curious to know if you found a way around this though? I am thinking of programmatically not logging during unit test

    2. Yuriy says:

      did you found out, how this solution can be used with mockServer?

  4. Sergey says:

    Reading inputStream due StreamUtils.copyToString(response.getBody(), Charset.defaultCharset())) or something else causes that body becomes empty and e.g. you will not be able to read body after GET method request. Seems like after response.getBody() inputStreas close and somehow body marks as read.

  5. Rashmi Shetty says:

    This messes up the error handling,

  6. jose says:

    Thank you. Works great.

  7. Raffaele Litto says:

    StreamUtils.copyToString and other StreamUtils methods do copy the InputStream but move the input stream index position to the end, so you won’t be able to reset the stream and consume it somewhere else.

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