MessageBodyReader and MessageBodyWriter Interceptors
31.1. MessageBodyReader/Writer Interceptors MessageBodyReader and Writer interceptors work off of the same principles. They wrap around the invocation of MessageBodyReader.readFrom() or MessageBodyWriter.writeTo(). You can use them to wrap the Output or InputStream. For example, the Resteasy GZIP support has interceptors that create and override the default Output and InputStream with a GzipOutpuStream or GzipInputStream so that gzip encoding can work. You could use them to append headers to the response (or on the client side, the outgoing request).