Jersey JAX-RS Client API Examples

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1. Overview

The Jersey JAX-RS Client API, which is a fluent Java-based API for communication with RESTful Web services. The JAX-RS client API can be utilized to consume any Web service exposed on top of an HTTP protocol. Follow below standard steps to write Jersey JAX RS Client API

• Creating and configuring a Client instance
• Targeting a web resource
• Identifying resource on WebTarget
• Invoking an HTTP request
• Complete Example

Let's write Jersey JAX RS Client for below Rest API's

HTTP GET - Collection/List of Users Example
HTTP GET - Get single User Rest API
HTTP POST - Create User Rest API
HTTP PUT - Update User Rest API
HTTP DELETE - Delete User Rest API

Let's write Rest API and it's the corresponding client for consume same rest API.

2. Jersey REST Client HTTP GET Collection/List of Users Example

Jersey Rest API code

@GET
@Produces(MediaType.APPLICATION_JSON)
public List<User> fetchAll() {
 return userService.fetchAll();
}

Client Code for Above Rest API This RESTful client code will access above API and print the response in the console.

private static void getUsers() {
 Client client = ClientBuilder.newClient();

 String entity = client.target("http://localhost:8080/jersey-crud-example/api").path("users")
   .request(MediaType.APPLICATION_JSON).header("some-header", "true").get(String.class);

 System.out.println(entity);
}

Output:

[{"email":"demo@gmail.com","id":100,"name":"A"},{"email":"demo1@gmail.com","id":101,"name":"B"},{"email":"demo2@gmail.com","id":102,"name":"C"}]

3. Jersey REST Client HTTP GET Single User Example

Jersey Rest API code

@GET
@Path("user/{id}")
@Produces(MediaType.APPLICATION_JSON)
public Response get(@PathParam("id") int id) {
 return Response.ok().entity(new User(100, "me", "me@gmail.com")).build();
}

Client Code This RESTful client code will access above API and print the response in the console.

private void getUserClientAPI() {
 Client client = ClientBuilder.newClient();

 String entity = client.target("http://localhost:8080/jersey-crud-example/api").path("users").path("user/100")
   .request(MediaType.APPLICATION_JSON).header("some-header", "true").get(String.class);

 System.out.println(entity);
}

Output:

{"email":"me@gmail.com","id":100,"name":"me"}

4. Jersey REST Client HTTP POST User API Example

Rest API

@POST
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
public Response create(User user) {
 // create notification
 userService.create(user);
 return Response.status(Status.CREATED).build();
}

Client Code

private static void createUserClientAPI() {
 Client client = ClientBuilder.newClient();
 WebTarget webTarget = client.target("http://localhost:8080/jersey-crud-example/api").path("users");

 User user = new User();
 user.setId(1);
 user.setName("Ramesh");

 Invocation.Builder invocationBuilder = webTarget.request(MediaType.APPLICATION_JSON);
 Response response = invocationBuilder.post(Entity.entity(user, MediaType.APPLICATION_JSON));

 System.out.println(response.getStatus());
 System.out.println(response.readEntity(String.class));
}

Output:

201

5. Jersey REST Client HTTP PUT User API Example

Rest API

@PUT
@Path("/user/{id}")
@Consumes(MediaType.APPLICATION_JSON)
public Response update(@PathParam("id") long id, User user) {
 userService.update(user);
 return Response.noContent().build();
}

Client Code

private static void updateUserClientAPI() {
 Client client = ClientBuilder.newClient();
 WebTarget webTarget = client.target("http://localhost:8080/jersey-crud-example/api").path("users")
   .path("user/1");

 User user = new User();
 user.setId(1);
 user.setName("Ramesh");

 Invocation.Builder invocationBuilder = webTarget.request(MediaType.APPLICATION_JSON);
 Response response = invocationBuilder.put(Entity.entity(user, MediaType.APPLICATION_JSON));

 String userJson = response.readEntity(String.class);

 System.out.println(response.getStatus());
 System.out.println(userJson);
}

6. Jersey REST Client HTTP DELETE User API Example

Rest API

@DELETE
@Path("/user/{id}")
public Response delete(@PathParam("id") long id) {
 userService.delete(id);
 return Response.status(202).entity("User deleted successfully !!").build();
}

Client Code

private static void deleteUser() {

 Client client = ClientBuilder.newClient();
 WebTarget webTarget = client.target("http://localhost:8080/jersey-crud-example/api").path("users")
   .path("user/100");

 User user = new User();
 user.setId(1);
 user.setName("Ramesh");

 Invocation.Builder invocationBuilder = webTarget.request();
 Response response = invocationBuilder.delete();

 System.out.println(response.getStatus());
 System.out.println(response.readEntity(String.class));
}

7. Conclusion

In this post, we have developed Jersey JAX-RS Client API for below API'S:

HTTP GET - Collection/List of Users Example
HTTP GET - Get single User Rest API
HTTP POST - Create User Rest API
HTTP PUT - Update User Rest API
HTTP DELETE - Delete User Rest API

You can learn more on the complete Jersey Rest Developer Guide
All the code of this article is available over on Github. This is a Maven-based project, so it should be easy to import and run as it is.

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