NullBodyToEmptyJsonContainerFilter for DW 0.7.1

NullBodyToEmptyJsonFilter.java

@Provider
@Slf4j
public class NullBodyToEmptyJsonFilter implements ContainerRequestFilter
{
    private static final String EMPTY_JSON_OBJECT = "{}";
    private static final byte[] EMPTY_JSON_BYTES = EMPTY_JSON_OBJECT.getBytes();

    @Override
    public ContainerRequest filter(ContainerRequest request) {
        MediaType mediaType = request.getMediaType();
        String method = request.getMethod();
        boolean isMethodPostOrPut = ("POST".equalsIgnoreCase(method) || "PUT".equalsIgnoreCase(method));
        boolean isJSON = MediaType.APPLICATION_JSON_TYPE.equals(mediaType);

        try
        {
            byte[] entityBuffer = new byte[1];
            int bytesRead = request.getEntityInputStream().read(entityBuffer);

            boolean isEntityEmpty = bytesRead == -1;

            InputStream entityStream;
            if (isMethodPostOrPut && isJSON && isEntityEmpty)
            {
                log.info("Got an empty entity body with method={} and mediaType={}. Will inject {} into the request",
                        method, mediaType, EMPTY_JSON_OBJECT);

                entityStream = new ByteArrayInputStream(EMPTY_JSON_BYTES);
            }
            else
            {
                entityStream = new SequenceInputStream(
                        new ByteArrayInputStream(entityBuffer),
                        request.getEntityInputStream());
            }

            request.setEntityInputStream(entityStream);
        }
        catch (IOException e)
        {
            log.error("Caught exception while trying to inject an empty JSON object into the request: {}\n.", e.getMessage(), e);
        }
        return request;
    }
}