@Slf4j

public class FlatBuffersHttpMessageConverter extends AbstractHttpMessageConverter<Table> {

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    public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");

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    public static final MediaType X_FLATBUFFERS = new MediaType("application", "x-fb", DEFAULT_CHARSET);

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    public static final String X_FLATBUFFERS_MESSAGE_ID = "X-FBS-MessageId";

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    protected final Map<String, FlatBuffersMessage> messageRepository;

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    public FlatBuffersHttpMessageConverter(Map<String, FlatBuffersMessage> messageRepository) {

        super(X_FLATBUFFERS);

        this.messageRepository = messageRepository;

    }

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    @Override

    protected boolean supports(Class<?> clazz) {

        return Table.class.isAssignableFrom(clazz);

    }

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    @Override

    protected Table readInternal(Class<? extends Table> clazz, HttpInputMessage inputMessage)

            throws IOException, HttpMessageNotReadableException {

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        final String messageId = inputMessage.getHeaders().getFirst(X_FLATBUFFERS_MESSAGE_ID);

        log.debug("Request.messageId: {}", messageId);

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        if(Objects.isNull(messageId) ||

                !messageRepository.containsKey(messageId)) {

            throw new HttpMessageNotReadableException("Unknown message protocol identifier");

        }

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        final long contentLength = inputMessage.getHeaders().getContentLength();

        final ByteArrayOutputStream out =

                new ByteArrayOutputStream(contentLength >= 0 ? (int) contentLength : StreamUtils.BUFFER_SIZE);

        StreamUtils.copy(inputMessage.getBody(), out);

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        return messageRepository.get(messageId).build(ByteBuffer.wrap(out.toByteArray()));

    }

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    @Override

    protected void writeInternal(Table message, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {

        setFlatBuffersResponseHeaders(message, outputMessage);

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        final byte[] dst = new byte[getContentLength(message, X_FLATBUFFERS).intValue()];

        message.getByteBuffer().get(dst);

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        StreamUtils.copy(dst, outputMessage.getBody());

    }

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    @Override

    protected Long getContentLength(Table table, MediaType contentType) throws IOException {

        final ByteBuffer buf = table.getByteBuffer();

        return (long) (buf.limit() - buf.position());

    }

​

}