Change ContentType or CharacterEncoding in Java Filter ONLY IF ContentType === JSON

Question

I\'m trying to ensure that all JSON responses from a Jersey based java application have a UTF-8 character encoding parameter appended to their ContentType header.

So

Answer 1

Had success using a ContainerResponseFilter:

public class ContentTypeEncodingFilter implements ContainerResponseFilter {
    @Override
    public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) throws IOException {
        String contentType = responseContext.getHeaderString(HttpHeaders.CONTENT_TYPE);
        if (contentType == null) {
            return;
        }
        ContentType parsedType = ContentType.parse(contentType);
        if (parsedType.getCharset() != null) {
            return;
        }
        ContentType encodedType = parsedType.withCharset(StandardCharsets.UTF_8);
        responseContext.getHeaders().putSingle(HttpHeaders.CONTENT_TYPE, encodedType.toString());
    }
}