Kafka custom deserializer converting to Java object

Question

I'm using Spring Kafka integration and I've my own value generic serializer/deserializer as shown below

Serializer:

public class KafkaSerializer<T> implements Serializer<T> {

  private ObjectMapper mapper;

  @Override
  public void close() {
  }

  @Override
  public void configure(final Map<String, ?> settings, final boolean isKey) {
    mapper = new ObjectMapper();
  }

  @Override
  public byte[] serialize(final String topic, final T object) {
    try {
      return mapper.writeValueAsBytes(object);
    } catch (final JsonProcessingException e) {
      throw new IllegalArgumentException(e);
    }
  }
}

Deserializer:

public class KafkaDeserializer<T> implements Deserializer<T> {

  private ObjectMapper mapper;

  @Override
  public void close() {
  }

  @Override
  public void configure(final Map<String, ?> settings, final boolean isKey) {
    mapper = new ObjectMapper();
  }

  @Override
  public T deserialize(final String topic, final byte[] bytes) {
    try {
      return mapper.readValue(bytes, new TypeReference<T>() {
      });
    } catch (final IOException e) {
      throw new IllegalArgumentException(e);
    }
  }
}

The serializer is working perfectly but when it comes to deserialization of values while consuming message I get a LinkedHashMap instead of desired object, please enlighten me where I'm mistaking, thanks in advance.

Answer 1

Some situations need be confirmed:

1. your Serializer is works
2. the Deserializer is just works but it returned a LinkedHashMap instead of a object that you expected, right? and you can't convert that LinkedHashMap to your object.

I find the question transfers to How to Convert/Cast a LinkedHashMap to a Object, and you used ObjectMapper. If all situations can be confirmed, I found here a good post may be answer your question Casting LinkedHashMap to Complex Object

mapper.convertValue(desiredObject, new TypeReference<type-of-desiredObject>() { })

ObjectMapper's API at [here](https://fasterxml.github.io/jackson-databind/javadoc/2.3.0/com/fasterxml/jackson/databind/ObjectMapper.html#convertValue(java.lang.Object, com.fasterxml.jackson.core.type.TypeReference))

And I hopes I don't missing your intention, and you can complement necessary situations, so someone or me can improve this answer.