Only default client supports GZIP response

[legendjaks]

The issue exists in OpenFeign 11.8, but it was working in 10.x.

Client.java

@Override
public Response execute(Request request, Options options) throws IOException {
  HttpURLConnection connection = convertAndSend(request, options);
  return convertResponse(connection, request);
}

Response convertResponse(HttpURLConnection connection, Request request) throws IOException {
  int status = connection.getResponseCode();
  String reason = connection.getResponseMessage();
  ...
  InputStream stream;
  if (status >= 400) {
    stream = connection.getErrorStream();
  } else {
    if (this.isGzip(connection.getHeaderFields().get(CONTENT_ENCODING))) {
      stream = new GZIPInputStream(connection.getInputStream());
    } else if (this.isDeflate(connection.getHeaderFields().get(CONTENT_ENCODING))) {
      stream = new InflaterInputStream(connection.getInputStream());
    } else {
      stream = connection.getInputStream();
    }
  }
 ...
}

ApacheHttpClient.java

public final class ApacheHttpClient implements Client {
  private static final String ACCEPT_HEADER_NAME = "Accept";

  private final HttpClient client;
  ...

  @Override
  public Response execute(Request request, Request.Options options) throws IOException {
    HttpUriRequest httpUriRequest;
    try {
      httpUriRequest = toHttpUriRequest(request, options);
    } catch (URISyntaxException e) {
      throw new IOException("URL '" + request.url() + "' couldn't be parsed into a URI", e);
    }
    HttpResponse httpResponse = client.execute(httpUriRequest);
    return toFeignResponse(httpResponse, request);
  }

If any client is used other than the default client, the GZIP content can't be decoded and results in an exception, because GZIP is read as simple InputStream, not GZIPInputStream

feign.codec.DecodeException: Error while extracting response for type [java.util.List<ProductDto>] and content type [application/json]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\r, \n, \t) is allowed between tokens; nested exception is com.fasterxml.jackson.core.JsonParseException: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\r, \n, \t) is allowed between tokens

[kdavisk6]

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[vitalijr2]

The default client uses a plain InputStream so it processes GZIP itself.

Other clients are based on third-party libraries who have OOB GZIP processing. So these cliens just wrappers and main processing is hidden inside the libraries.

For example: HC5 has the special feature switcher disableContentCompression() but by default this feature is on. See

feign/hc5/src/test/java/feign/hc5/ApacheHttp5ClientTest.java

Line 47 in 83c3d69

.client(new ApacheHttp5Client(httpClient))

and previous 44 line.

Could you check that someone client fails to process a GZIP response, please?
Thank you.

[legendjaks]

Verified using io.github.openfeign:feign-httpclient:11.9 client. The issue exists.

feign/httpclient/src/main/java/feign/httpclient/ApacheHttpClient.java

Line 215 in 83c3d69

public InputStream asInputStream() throws IOException {

The above method has to return GZIPInputStream or InflaterInputStream if content-encoding is gzip/deflate, but it always returns InputStream. In the local code, changed this to GZIPInputStream and it worked.

[vitalijr2]

The default client has some compression tests for gzip and deflate. I've moved them to the client abstract test class.

Bunch of clients support gzip and deflate, Apache HTTP client too. As I've wrote a client just wrappes a third-party client and all "magic" to process gzip or deflate hides in this third-party code. So when the client gets gzip or deflate response it does not decompress it itself.

But some third-party libraris do not process decompression out-of-the-box.

• OkHTTP client with an interceptor can proccess GZIP response, e.g. https://stackoverflow.com/questions/51901333/okhttp-3-how-to-decompress-gzip-deflate-response-manually-using-java-android
• Google HTTP client with NetHttpTransport does not support GZIP response at all but we can use Apache HTTP client as its transport
• JAX-RS2 client does not support GZIP responses out-of-the-box but we can register a class that implies it like Jersey implementation does it, see https://stackoverflow.com/questions/22519642/how-to-enable-gzip-compression-for-content-encoding-with-jersey-jax-rs-2-0-cli