Stack Overflow http://stackoverflow.com/q/35013157/2587435

HeaderInFilterTest.java

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.logging.Logger;

import javax.ws.rs.Consumes;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.client.ClientRequestContext;
import javax.ws.rs.client.ClientRequestFilter;
import javax.ws.rs.client.Entity;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.Response;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.MessageBodyWriter;

import org.glassfish.jersey.client.ClientConfig;
import org.glassfish.jersey.filter.LoggingFilter;
import org.glassfish.jersey.message.internal.ReaderWriter;
import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.test.JerseyTest;
import org.junit.Test;

import static junit.framework.Assert.assertEquals;

/**
 * Stack Overflow http://stackoverflow.com/q/35013157/2587435
 *
 * @author Paul Samsotha
 */
public class HeaderInFilterTest extends JerseyTest {

	public static class HeaderEntity {

		public String header;
		public String entity;

		public HeaderEntity(String header, String entity) {
			this.header = header;
			this.entity = entity;
		}
	}

	private static final String HEADER = "X-Custom-Header";

	@Produces("application/x-custom")
	public static class HeaderEntityWriter implements MessageBodyWriter<HeaderEntity> {

		@Override
		public boolean isWriteable(Class<?> type, Type genericType,
				Annotation[] annotations, MediaType mediaType) {
			return HeaderEntity.class == type;
		}

		@Override
		public long getSize(HeaderEntity t, Class<?> type, Type genericType,
				Annotation[] annotations, MediaType mediaType) {
			return -1;
		}

		@Override
		public void writeTo(HeaderEntity entity, Class<?> type, Type genericType,
				Annotation[] annotations, MediaType mediaType,
				MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
				throws IOException, WebApplicationException {
			//httpHeaders.putSingle(HEADER, entity.header);
			entityStream.write(entity.entity.getBytes());
		}
	}

	@Consumes("application/x-custom")
	public static class HeaderEntityReader implements MessageBodyReader<HeaderEntity> {

		@Override
		public boolean isReadable(Class<?> type, Type genericType,
				Annotation[] annotations, MediaType mediaType) {
			return HeaderEntity.class == type;
		}

		@Override
		public HeaderEntity readFrom(Class<HeaderEntity> type, Type genericType,
				Annotation[] annotations, MediaType mediaType,
				MultivaluedMap<String, String> httpHeaders, InputStream entityStream)
				throws IOException, WebApplicationException {
			String s = ReaderWriter.readFromAsString(entityStream, MediaType.TEXT_PLAIN_TYPE);
			return new HeaderEntity(httpHeaders.getFirst(HEADER), s);
		}
	}

	public static class HeaderFilter implements ClientRequestFilter {

		@Override
		public void filter(ClientRequestContext requestContext) throws IOException {
			Object entity = requestContext.getEntity();
			if (entity instanceof HeaderEntity) {
				HeaderEntity headerEntity = (HeaderEntity) entity;
				requestContext.getHeaders().putSingle(HEADER, headerEntity.header);
			}
		}

	}

	@Path("test")
	public static class TestResource {

		@POST
		@Consumes("application/x-custom")
		public String post(HeaderEntity entity) {
			return entity.header + ":" + entity.entity;
		}
	}

	@Override
	public ResourceConfig configure() {
		return new ResourceConfig(TestResource.class)
				.register(HeaderEntityReader.class)
				.register(new LoggingFilter(Logger.getAnonymousLogger(), true));
	}

	@Override
	public void configureClient(ClientConfig config) {
		config.register(HeaderEntityWriter.class);
		config.register(HeaderFilter.class);
	}

	@Test
	public void shouldReturnHeaderAndEntity() {

		Response response = target("test").request()
				.post(Entity.entity(new HeaderEntity("header", "entity"), "application/x-custom"));
		assertEquals(200, response.getStatus());
		assertEquals("header:entity", response.readEntity(String.class));
	}
}