Confluent Kafka Avro deserializer for spring boot kafka listener - spring

Question

Does somebody implemented confluent-kafka messages deserializer to consume kafka messages by spring "#KafkaListener"-s ?

Answer 1

Here is my answer, which I've implemented based on: "io.confluent.kafka.serializers.AbstractKafkaAvroDeserializer"
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Map;
import javax.xml.bind.DatatypeConverter;
import org.apache.avro.Schema;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificRecordBase;
import org.apache.kafka.common.errors.SerializationException;
import org.apache.kafka.common.serialization.Deserializer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class AvroConfluentDeserializer<T extends SpecificRecordBase> implements Deserializer<T> {
private static final Logger LOG = LoggerFactory.getLogger(AvroConfluentDeserializer.class);
protected static final byte MAGIC_BYTE = 0x0;
protected static final int idSize = 4;
private final DecoderFactory decoderFactory = DecoderFactory.get();
protected final Class<T> targetType;
public AvroConfluentDeserializer(Class<T> targetType) {
this.targetType = targetType;
}
#Override
public void close() {
// No-op
}
#Override
public void configure(Map<String, ?> arg0, boolean arg1) {
// No-op
}
#Override
public T deserialize(String topic, byte[] data) {
try {
T result = null;
if (data != null) {
LOG.info("data='{}'", DatatypeConverter.printHexBinary(data));
result = (T) deserializePayload(data, targetType.newInstance().getSchema());
LOG.info("deserialized data='{}'", result);
}
return result;
} catch (Exception ex) {
throw new SerializationException(
"Can't deserialize data '" + Arrays.toString(data) + "' from topic '" + topic + "'", ex);
}
}
protected T deserializePayload(byte[] payload, Schema schema) throws SerializationException {
int id = -1;
try {
ByteBuffer buffer = getByteBuffer(payload);
id = buffer.getInt();
int length = buffer.limit() - 1 - idSize;
int start = buffer.position() + buffer.arrayOffset();
DatumReader<T> reader = new SpecificDatumReader<T>(schema);
return reader.read(null, decoderFactory.binaryDecoder(buffer.array(), start, length, null));
} catch (IOException | RuntimeException e) {
throw new SerializationException("Error deserializing Avro message for id " + id, e);
}
}
private ByteBuffer getByteBuffer(byte[] payload) {
ByteBuffer buffer = ByteBuffer.wrap(payload);
if (buffer.get() != MAGIC_BYTE) {
throw new SerializationException("Unknown magic byte!");
}
return buffer;
}
}