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In the previous tutorial, we have developed CRUD restful web services using RESTEasy.In this tutorial, we will learn how to build a RESTful client for consuming GET, POST, PUT and DELETE RESTFul APIs.

JAX-RS 2.0 Client API Overview

JAX-RS 2.0 introduces a new client API so that you can make HTTP requests to your remote RESTful web services. It is a 'fluent' request building API with really 3 main classes: Client, WebTarget, and Response.

The Client interface is a builder of WebTarget instances.

WebTarget represents a distinct URL or URL template from which you can build more sub-resource WebTargets or invoke requests on.

There are really two ways to create a Client. The standard way or you can use the ResteasyClientBuilder class. The advantage of the latter is that it gives you a few more helper methods to configure your client. Sample code:

            Client client = ClientBuilder.newClient();
            ... or...
            Client client = ClientBuilder.newBuilder().build();
            WebTarget target = client.target("http://foo.com/resource");
            Response response = target.request().get();
            String value = response.readEntity(String.class);
            response.close();  // You should close connections!

            ResteasyClient client = new ResteasyClientBuilder().build();
            ResteasyWebTarget target = client.target("http://foo.com/resource");

Update pom.xml File

Add a resteasy-client dependency in your pom.xml:

<dependency>
   <groupId>org.jboss.resteasy</groupId>
   <artifactId>resteasy-client</artifactId>
   <version>3.9.3.Final</version>
</dependency>

JAX-RS RESTEasy APIs

I will be re-using the codebase written for the RESTEasy CRUD example tutorial.

package net.javaguides.resteasy.resource;

import java.util.List;

import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import net.javaguides.resteasy.model.User;
import net.javaguides.resteasy.service.UserService;

/**
 * CRUD Rest APIs for User Resource
 * @author Ramesh Fadatare
 *
 */

@Path("users")
public class UserResource {

    private UserService userService = new UserService();

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Response getUsers() {

        List < User > users = userService.findAll();

        if (!users.isEmpty()) {
            return Response.ok(users).build();
        } else {
            return Response.status(Response.Status.NOT_FOUND).build();
        }
    }

    @Path("/{id}")
    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Response getUserById(@PathParam("id") Long id) {

        User user = userService.fetchBy(id);

        if (user.getId() != null) {
            return Response.ok(user).build();
        } else {
            return Response.status(Response.Status.NOT_FOUND).build();
        }
    }

    @POST
    @Produces(MediaType.APPLICATION_JSON)
    @Consumes(MediaType.APPLICATION_JSON)
    public Response createUser(User user) {
        boolean result = userService.create(user);
        if (result) {
            return Response.ok().status(Response.Status.CREATED).build();
        } else {
            return Response.notModified().build();
        }
    }


    @PUT
    @Path("/{id}")
    @Consumes(MediaType.APPLICATION_JSON)
    public Response updateUser(@PathParam("id") long id, User user) {
        boolean result = userService.update(user);

        if (result) {
            return Response.ok().status(Response.Status.NO_CONTENT).build();
        } else {
            return Response.notModified().build();
        }
    }


    @Path("/{id}")
    @DELETE
    @Produces(MediaType.APPLICATION_JSON)
    public Response deleteUser(@PathParam("id") Long id) {
        boolean result = userService.delete(id);

        if (result) {
            return Response.ok().status(Response.Status.NO_CONTENT).build();
        } else {
            return Response.notModified().build();
        }
    }
}

RESTEasy Client for GET, POST, PUT and DELETE RESTFul APIs

Let's create a JUnit test cases to GET, POST, PUT and DELETE Rest web services with RESTEasy:

package net.javaguides.resteasy;

import javax.ws.rs.client.Entity;
import javax.ws.rs.core.Response;

import org.jboss.resteasy.client.jaxrs.ResteasyClient;
import org.jboss.resteasy.client.jaxrs.ResteasyClientBuilder;
import org.jboss.resteasy.client.jaxrs.ResteasyWebTarget;
import org.junit.Test;

import net.javaguides.resteasy.model.User;

public class UserResourceTest {

    private static final String FULL_PATH = "http://localhost:8080/resteasy-crud-example-tutorial/restapi/users";

    @Test
    public void testListAllUsers() {

        final ResteasyClient client = new ResteasyClientBuilder().build();
        final ResteasyWebTarget target = client
            .target(FULL_PATH);
        String response = target.request().get(String.class);
        System.out.println(response);
    }

    @Test
    public void testGetUser() {

        final ResteasyClient client = new ResteasyClientBuilder().build();
        final ResteasyWebTarget target = client
            .target(FULL_PATH + "/100");
        Response response = target.request().get();
        User user = response.readEntity(User.class);
        System.out.println(user.toString());
        response.close();
    }

    @Test
    public void testCreateUser() {
        ResteasyClient client = new ResteasyClientBuilder().build();
        ResteasyWebTarget target = client.target(FULL_PATH);
        Response response = target.request()
            .post(Entity.entity(new User(100 L, "Amir", "amir@gmail.com"), "application/json"));
        System.out.println(response.getStatus());
        response.close();
    }

    @Test
    public void testUpdateUser() {
        User user = new User();
        user.setName("Ram");
        user.setEmail("ram@gmail.com");
        ResteasyClient client = new ResteasyClientBuilder().build();
        ResteasyWebTarget target = client.target(FULL_PATH + "/100");
        Response response = target.request()
            .put(Entity.entity(user, "application/json"));
        System.out.println(response.getStatus());
        response.close();
    }

    @Test
    public void testDeleteUser() {
        ResteasyClient client = new ResteasyClientBuilder().build();
        ResteasyWebTarget target = client.target(FULL_PATH + "/101");
        Response response = target.request()
            .delete();
        System.out.println(response.getStatus());
        response.close();

        final ResteasyWebTarget target1 = client
            .target(FULL_PATH);
        String response1 = target1.request().get(String.class);
        System.out.println(response1);
    }
}