ServletRequestClientInjectTest.java

import java.io.IOException;

import javax.inject.Inject;
import javax.inject.Singleton;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.ws.rs.GET;
import javax.ws.rs.HeaderParam;
import javax.ws.rs.Path;
import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.ClientRequestContext;
import javax.ws.rs.client.ClientRequestFilter;
import javax.ws.rs.core.Feature;
import javax.ws.rs.core.FeatureContext;

import org.glassfish.jersey.InjectionManagerProvider;
import org.glassfish.jersey.internal.inject.AbstractBinder;
import org.glassfish.jersey.internal.inject.InjectionManager;
import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.servlet.ServletContainer;
import org.glassfish.jersey.test.DeploymentContext;
import org.glassfish.jersey.test.JerseyTest;
import org.glassfish.jersey.test.ServletDeploymentContext;
import org.glassfish.jersey.test.grizzly.GrizzlyWebTestContainerFactory;
import org.glassfish.jersey.test.spi.TestContainerFactory;
import org.junit.Test;

import static org.assertj.core.api.Assertions.assertThat;

/**
 * Test for Stack Overflow question https://stackoverflow.com/q/66354154/2587435
 * Below are all the required dependencies to run the test
 *
 *  <dependency>
 *     <groupId>org.glassfish.jersey.test-framework.providers</groupId>
 *     <artifactId>jersey-test-framework-provider-grizzly2</artifactId>
 *     <version>2.25.1</version>
 *     <scope>test</scope>
 *  </dependency>
 *  <dependency>
 *     <groupId>org.assertj</groupId>
 *     <artifactId>assertj-core</artifactId>
 *     <version>3.14.0</version>
 *     <scope>test</scope>
 *  </dependency>
 */
public class ServletRequestClientInjectTest extends JerseyTest  {

    /**
     * Sets an HttpServletRequest attribute that will be retrieved later
     */
    public static class AttributeFilter implements Filter {

        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
                throws IOException, ServletException {
            HttpServletRequest servletRequest = (HttpServletRequest) request;
            servletRequest.setAttribute("test-attribute", "test-value");
            chain.doFilter(servletRequest, response);
        }
    }

    /**
     * Configuration for servlet environment in JerseyTest
     */
    @Override
    public DeploymentContext configureDeployment() {
        return ServletDeploymentContext.forServlet(new ServletContainer(configure()))
                .addFilter(AttributeFilter.class, "AttributeFilter")
                .build();
    }

    /**
     * Configuration for servlet environment in JerseyTest
     */
    @Override
    public TestContainerFactory getTestContainerFactory() {
        return new GrizzlyWebTestContainerFactory();
    }

    /**
     * Configure Jersey application
     */
    @Override
    public ResourceConfig configure() {
        return new ResourceConfig()
                .register(TestResource.class)
                .register(ClientFeature.class);
    }

    /**
     * Client feature that creates complete client injectable
     */
    public static class ClientFeature implements Feature {

        @Override
        public boolean configure(FeatureContext context) {
            InjectionManager im = InjectionManagerProvider.getInjectionManager(context);
            context.register(new ClientBinder(im));
            return true;
        }

        /**
         * Client binder for injection framework
         */
        private static class ClientBinder extends AbstractBinder {

            private final InjectionManager im;

            private ClientBinder(InjectionManager im) {
                this.im = im;
            }

            @Override
            protected void configure() {
                ClientFilter clientFilter = new ClientFilter();
                im.inject(clientFilter);
                Client client = ClientBuilder.newClient()
                        .register(clientFilter);
                bind(client).to(Client.class).in(Singleton.class);
            }
        }

        /**
         * Client filter gets attribute from HttpServletRequest and sets it
         * in client filter header.
         */
        private static class ClientFilter implements ClientRequestFilter {

            @Inject
            private HttpServletRequest servletRequest;

            @Override
            public void filter(ClientRequestContext requestContext) throws IOException {
                String testAttr = (String) servletRequest.getAttribute("test-attribute");
                requestContext.getHeaders().putSingle("Test-Header", testAttr);
            }
        }
    }

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

        @Inject
        Client client;

        /**
         * Method test client is calling; will forward call to `getClientCall()`
         */
        @GET
        public String get() {
            return client.target("http://localhost:9998/test/client")
                    .request()
                    .get(String.class);
        }

        /**
         * Test method to get test-header from client call
         */
        @GET
        @Path("client")
        public String getClientCall(@HeaderParam("Test-Header") String testHeader) {
            return testHeader;
        }
    }

    @Test
    public void testIt() {
        String res = target("test").request().get(String.class);
        System.out.println(res);
        assertThat(res).isEqualTo("test-value");
    }
}