Class JacksonDecoder

jackson/src/main/java/feign/jackson/JacksonDecoder.java:32–79

import java.util.Collections;

public class JacksonDecoder implements Decoder, JsonDecoder {

  private final ObjectMapper mapper;

  public JacksonDecoder() {
    this(Collections.<Module>emptyList());
  }

  public JacksonDecoder(Iterable<Module> modules) {
    this(
        new ObjectMapper()
            .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
            .registerModules(modules));
  }

  public JacksonDecoder(ObjectMapper mapper) {
    this.mapper = mapper;
  }

  @Override
  public Object decode(Response response, Type type) throws IOException {
    if (response.status() == 404 || response.status() == 204) return Util.emptyValueOf(type);
    if (response.body() == null) return null;
    Reader reader = response.body().asReader(response.charset());
    if (!reader.markSupported()) {
      reader = new BufferedReader(reader, 1);
    }
    try {
      // Read the first byte to see if we have any data
      reader.mark(1);
      if (reader.read() == -1) {
        return null; // Eagerly returning null avoids "No content to map due to end-of-input"
      }
      reader.reset();
      return mapper.readValue(reader, mapper.constructType(type));
    } catch (RuntimeJsonMappingException e) {
      if (e.getCause() != null && e.getCause() instanceof IOException) {
        throw IOException.class.cast(e.getCause());
      }
      throw e;
    }
  }

  @Override
  public Object convert(Object object, Type type) {
    return mapper.convertValue(object, mapper.constructType(type));
  }
}