OkHttp Example REST Client

Jumping off the lightweight Java REST server we created in the last article, this tutorial lets us get programmatic access to our API in Java using OkHttp.

Bill O'Neil

May. 13, 17 · Tutorial

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Previously we created a Lightweight Java REST server using Undertow. It was only tested with cURL which is an exceptional tool for testing and debugging, however, we love Java! Let's get some programmatic access to our API in Java using OkHttp. We will be working with query parameters, HTTP verbs (GET, POST, PUT, DELETE), status codes, as well as serializing and deserializing JSON with Jackson.

OkHttp's HttpUrl and Request

Two fundamental parts of making a request with an OkHttpClient are the HttpUrl and the Request.Builder . HttpUrl is a convenient way to build URLs in Java. It supports a simple parse(String host) method for parsing a String or you can build the URL manually. It allows easily adding query parameters, path parameters are less intuitive but still easy enough (Look into Retrofit for better REST API support). The Request.Builder is responsible for most other aspects of the request including HTTP verb, headers, cookies, media types, etc

RestClient

RestClient will be our class responsible for interacting with the REST service. Its constructor is straightforward. Pass in an OkHttpClient and a hostname for the API.

private final String host;
private final OkHttpClient client;
public RestClient(String host, OkHttpClient client) {
    super();
    this.host = host;
    this.client = client;
}

View on GitHub.

Creating a User

According to our API we need to POST JSON to /users . Notice how we care about that status codes of the response. We know the API returns a 201 on successful creation so let's look for that. We prefer to return null instead of throwing an exception on a failure to create user due to a 400 status code. This means the user already exists.

public User createUser(User inputUser) {
    HttpUrl route = HttpUrl.parse(host + "/users");
    Request request = new Request.Builder()
        .url(route)
        .post(RequestBodies.jsonObj(inputUser))
        .build();
    return Unchecked.supplier(() -> {
        try (Response response = client.newCall(request).execute()) {
            if (response.code() == StatusCodes.CREATED) {
                User user = Json.serializer().fromInputStream(response.body().byteStream(), User.typeRef());
                return user;
            }

            if (response.code() == StatusCodes.BAD_REQUEST) {
                return null;
            }
            throw HttpClient.unknownException(response);
        }
    }).get();
}

View on GitHub.

Updating a User

For an update we need to send a PUT request to /users with the updated User object. On a 404 (not found) we return null instead of throwing an exception.

public User updateUser(User inputUser) {
    HttpUrl route = HttpUrl.parse(host + "/users");
    Request request = new Request.Builder()
            .url(route)
            .put(RequestBodies.jsonObj(inputUser))
            .build();
    return Unchecked.supplier(() -> {
        try (Response response = client.newCall(request).execute()) {
            if (response.isSuccessful()) {
                User user = Json.serializer().fromInputStream(response.body().byteStream(), User.typeRef());
                return user;
            }

            if (response.code() == StatusCodes.NOT_FOUND) {
                return null;
            }
            throw HttpClient.unknownException(response);
        }
    }).get();
}

View on GitHub.

Listing Users

Listing users requires sending a GET request to /users . Since this is a simple example it will just return all users with no filtering or paginations options available. response.isSuccessful() is a convenience method that checks if the response is any 20x status code.

public List<User> listUsers() {
    HttpUrl route = HttpUrl.parse(host + "/users");
    Request request = new Request.Builder().url(route).get().build();
    return Unchecked.supplier(() -> {
        try (Response response = client.newCall(request).execute()) {
            if (response.isSuccessful()) {
                List<User> users = Json.serializer().fromInputStream(response.body().byteStream(), User.listTypeRef());
                return users;
            }
            throw HttpClient.unknownException(response);
        }
    }).get();
}

View on GitHub.

Get User by Email

Since we are using email as our primary key in this example we can fetch users by sending a GET request to /users/{email} . Once again we handle 404 s by returning null.

public User getUserByEmail(String email) {
    HttpUrl route = HttpUrl.parse(host + "/users")
                           .newBuilder()
                           .addPathSegment(email)
                           .build();
    Request request = new Request.Builder().url(route).get().build();
    return Unchecked.supplier(() -> {
        try (Response response = client.newCall(request).execute()) {
            // The user exists
            if (response.isSuccessful()) {
                User user = Json.serializer().fromInputStream(response.body().byteStream(), User.typeRef());
                return user;
            }

            /*
             *  404 Not Found - Either return null or throw your own exception.
             *  We prefer nulls.
             */
            if (response.code() == StatusCodes.NOT_FOUND) {
                return null;
            }
            throw HttpClient.unknownException(response);
        }
    }).get();
}

View on GitHub.

Delete User by Email

Deleting a user can be accomplished by sending a DELETE request to /users/{email}.

public boolean deleteUserByEmail(String email) {
    HttpUrl route = HttpUrl.parse(host + "/users")
                           .newBuilder()
                           .addPathSegment(email)
                           .build();
    Request request = new Request.Builder().url(route).delete().build();
    return Unchecked.booleanSupplier(() -> {
        try (Response response = client.newCall(request).execute()) {
            if (response.code() == StatusCodes.NO_CONTENT) {
                return true;
            }

            // Maybe you would throw an exception here? We don't feel the need to.
            if (response.code() == StatusCodes.NOT_FOUND) {
                return false;
            }
            throw HttpClient.unknownException(response);
        }
    }).getAsBoolean();
}

View on GitHub.

Example Usage

If you want to test this locally make sure you also start up the example REST service.

public static void main(String[] args) {
    RestClient client = new RestClient("http://localhost:8080", HttpClient.globalClient());

    log.debug("**** Creating Users ****");
    User user1 = new User("user1@test.com", Sets.newHashSet(Role.USER), LocalDate.now());
    log.debug(Json.serializer().toString(client.createUser(user1)));
    User user2 = new User("user2@test.com", Sets.newHashSet(Role.ADMIN), LocalDate.now());
    log.debug(Json.serializer().toString(client.createUser(user2)));

    log.debug("\n\n");
    log.debug("**** Updating User ****");
    User user2Updated = new User("user2@test.com", Sets.newHashSet(Role.ADMIN, Role.USER), LocalDate.now());
    log.debug(Json.serializer().toString(client.updateUser(user2Updated)));

    log.debug("\n\n");
    log.debug("**** Listing Users ****");
    List<User> users = client.listUsers();
    log.debug(Json.serializer().toString(users));

    log.debug("\n\n");
    log.debug("**** Get Users ****");
    log.debug(Json.serializer().toString(client.getUserByEmail("user1@test.com")));
    log.debug(Json.serializer().toString(client.getUserByEmail("user2@test.com")));

    log.debug("\n\n");
    log.debug("**** Delete Users ****");
    client.deleteUserByEmail("user1@test.com");

    log.debug("\n\n");
    log.debug("**** Get Missing User ****");
    log.debug(Json.serializer().toString(client.getUserByEmail("user1@test.com")));

    log.debug("\n\n");
    log.debug("**** Exception ****");
    log.debug(Json.serializer().toString(client.createUser(null)));
}

View on GitHub.

Server Log

2017-03-21 11:28:35.975 [main] DEBUG c.s.common.undertow.SimpleServer - ListenerInfo{protcol='http', address=/0:0:0:0:0:0:0:0:8080, sslContext=null}
2017-03-21 11:33:15.388 [XNIO-1 task-1] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "POST /users HTTP/1.1" 201 96 "-" "okhttp/3.6.0"
2017-03-21 11:33:15.466 [XNIO-1 task-2] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "POST /users HTTP/1.1" 201 97 "-" "okhttp/3.6.0"
2017-03-21 11:33:15.478 [XNIO-1 task-3] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "PUT /users HTTP/1.1" 200 105 "-" "okhttp/3.6.0"
2017-03-21 11:33:15.505 [XNIO-1 task-4] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "GET /users HTTP/1.1" 200 117 "-" "okhttp/3.6.0"
2017-03-21 11:33:15.520 [XNIO-1 task-5] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "GET /users/user1@test.com HTTP/1.1" 200 96 "-" "okhttp/3.6.0"
2017-03-21 11:33:15.527 [XNIO-1 task-6] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "GET /users/user2@test.com HTTP/1.1" 200 105 "-" "okhttp/3.6.0"
2017-03-21 11:33:15.542 [XNIO-1 task-7] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "DELETE /users/user1@test.com HTTP/1.1" 204 - "-" "okhttp/3.6.0"
2017-03-21 11:33:15.550 [XNIO-1 task-8] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "GET /users/user1@test.com HTTP/1.1" 404 85 "-" "okhttp/3.6.0"
2017-03-21 11:33:15.559 [XNIO-1 task-9] ERROR c.s.c.u.handlers.CustomHandlers - exception thrown at /users
java.lang.NullPointerException: null
  at com.stubbornjava.examples.undertow.rest.UserRoutes.createUser(UserRoutes.java:17)
  at com.stubbornjava.examples.undertow.rest.RestServer$$Lambda$5/1990160809.handleRequest(Unknown Source)
  at com.stubbornjava.common.undertow.handlers.TimingHttpHandler.handleRequest(TimingHttpHandler.java:27)
  at io.undertow.server.RoutingHandler.handleRequest(RoutingHandler.java:93)
  at com.stubbornjava.examples.undertow.rest.RestServer.lambda$0(RestServer.java:38)
  at com.stubbornjava.examples.undertow.rest.RestServer$$Lambda$11/76432244.handleRequest(Unknown Source)
  at com.stubbornjava.common.undertow.handlers.CustomHandlers.lambda$1(CustomHandlers.java:102)
  at com.stubbornjava.common.undertow.handlers.CustomHandlers$$Lambda$12/1030228826.handleRequest(Unknown Source)
  at io.undertow.server.handlers.ExceptionHandler.handleRequest(ExceptionHandler.java:29)
  at com.stubbornjava.common.undertow.handlers.StatusCodeHandler.handleRequest(StatusCodeHandler.java:27)
  at io.undertow.server.handlers.accesslog.AccessLogHandler.handleRequest(AccessLogHandler.java:138)
  at io.undertow.server.handlers.encoding.EncodingHandler.handleRequest(EncodingHandler.java:72)
  at io.undertow.server.Connectors.executeRootHandler(Connectors.java:210)
  at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:809)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at java.lang.Thread.run(Thread.java:745)
2017-03-21 11:33:15.561 [XNIO-1 task-9] INFO  com.stubbornjava.accesslog - 127.0.0.1 - - [21/Mar/2017:11:33:15 -0400] "POST /users HTTP/1.1" 500 77 "-" "okhttp/3.6.0"

Output

Since our OkHttpClient has been configured with a Logging Interceptor we get very detailed output. You would want this level of logging turned off in production.

2017-03-21 11:33:14.584 [main] DEBUG c.s.e.undertow.rest.RestClient - **** Creating Users ****
2017-03-21 11:33:14.925 [main] DEBUG com.stubbornjava.common.HttpClient - --> POST http://localhost:8080/users http/1.1
2017-03-21 11:33:14.925 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json; charset=utf-8
2017-03-21 11:33:14.925 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 70
2017-03-21 11:33:14.925 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:14.925 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:14.925 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:14.925 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:14.927 [main] DEBUG com.stubbornjava.common.HttpClient -
2017-03-21 11:33:14.927 [main] DEBUG com.stubbornjava.common.HttpClient - {"email":"user1@test.com","roles":["USER"],"dateCreated":"2017-03-21"}
2017-03-21 11:33:14.927 [main] DEBUG com.stubbornjava.common.HttpClient - --> END POST (70-byte body)
2017-03-21 11:33:15.391 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 201 Created http://localhost:8080/users (463ms)
2017-03-21 11:33:15.391 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Encoding: gzip
2017-03-21 11:33:15.391 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: keep-alive
2017-03-21 11:33:15.391 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json
2017-03-21 11:33:15.391 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 96
2017-03-21 11:33:15.391 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.391 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP (encoded body omitted)
2017-03-21 11:33:15.430 [main] DEBUG c.s.e.undertow.rest.RestClient - {"email":"user1@test.com","roles":["USER"],"dateCreated":"2017-03-21"}
2017-03-21 11:33:15.435 [main] DEBUG com.stubbornjava.common.HttpClient - --> POST http://localhost:8080/users http/1.1
2017-03-21 11:33:15.435 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json; charset=utf-8
2017-03-21 11:33:15.435 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 71
2017-03-21 11:33:15.435 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:15.435 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:15.435 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:15.435 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:15.436 [main] DEBUG com.stubbornjava.common.HttpClient -
2017-03-21 11:33:15.436 [main] DEBUG com.stubbornjava.common.HttpClient - {"email":"user2@test.com","roles":["ADMIN"],"dateCreated":"2017-03-21"}
2017-03-21 11:33:15.437 [main] DEBUG com.stubbornjava.common.HttpClient - --> END POST (71-byte body)
2017-03-21 11:33:15.469 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 201 Created http://localhost:8080/users (31ms)
2017-03-21 11:33:15.469 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Encoding: gzip
2017-03-21 11:33:15.469 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: keep-alive
2017-03-21 11:33:15.469 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json
2017-03-21 11:33:15.469 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 97
2017-03-21 11:33:15.470 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.470 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP (encoded body omitted)
2017-03-21 11:33:15.471 [main] DEBUG c.s.e.undertow.rest.RestClient - {"email":"user2@test.com","roles":["ADMIN"],"dateCreated":"2017-03-21"}
2017-03-21 11:33:15.471 [main] DEBUG c.s.e.undertow.rest.RestClient -


2017-03-21 11:33:15.472 [main] DEBUG c.s.e.undertow.rest.RestClient - **** Updating User ****
2017-03-21 11:33:15.474 [main] DEBUG com.stubbornjava.common.HttpClient - --> PUT http://localhost:8080/users http/1.1
2017-03-21 11:33:15.474 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json; charset=utf-8
2017-03-21 11:33:15.475 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 78
2017-03-21 11:33:15.475 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:15.475 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:15.475 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:15.475 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:15.475 [main] DEBUG com.stubbornjava.common.HttpClient -
2017-03-21 11:33:15.475 [main] DEBUG com.stubbornjava.common.HttpClient - {"email":"user2@test.com","roles":["USER","ADMIN"],"dateCreated":"2017-03-21"}
2017-03-21 11:33:15.475 [main] DEBUG com.stubbornjava.common.HttpClient - --> END PUT (78-byte body)
2017-03-21 11:33:15.481 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 200 OK http://localhost:8080/users (6ms)
2017-03-21 11:33:15.482 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Encoding: gzip
2017-03-21 11:33:15.482 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: keep-alive
2017-03-21 11:33:15.482 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json
2017-03-21 11:33:15.482 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 105
2017-03-21 11:33:15.482 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.482 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP (encoded body omitted)
2017-03-21 11:33:15.482 [main] DEBUG c.s.e.undertow.rest.RestClient - {"email":"user2@test.com","roles":["USER","ADMIN"],"dateCreated":"2017-03-21"}
2017-03-21 11:33:15.482 [main] DEBUG c.s.e.undertow.rest.RestClient -


2017-03-21 11:33:15.483 [main] DEBUG c.s.e.undertow.rest.RestClient - **** Listing Users ****
2017-03-21 11:33:15.485 [main] DEBUG com.stubbornjava.common.HttpClient - --> GET http://localhost:8080/users http/1.1
2017-03-21 11:33:15.485 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:15.485 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:15.485 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:15.486 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:15.486 [main] DEBUG com.stubbornjava.common.HttpClient - --> END GET
2017-03-21 11:33:15.510 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 200 OK http://localhost:8080/users (23ms)
2017-03-21 11:33:15.511 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Encoding: gzip
2017-03-21 11:33:15.511 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: keep-alive
2017-03-21 11:33:15.511 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json
2017-03-21 11:33:15.511 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 117
2017-03-21 11:33:15.511 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.511 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP (encoded body omitted)
2017-03-21 11:33:15.514 [main] DEBUG c.s.e.undertow.rest.RestClient - [{"email":"user1@test.com","roles":["USER"],"dateCreated":"2017-03-21"},{"email":"user2@test.com","roles":["USER","ADMIN"],"dateCreated":"2017-03-21"}]
2017-03-21 11:33:15.515 [main] DEBUG c.s.e.undertow.rest.RestClient -


2017-03-21 11:33:15.515 [main] DEBUG c.s.e.undertow.rest.RestClient - **** Get Users ****
2017-03-21 11:33:15.515 [main] DEBUG com.stubbornjava.common.HttpClient - --> GET http://localhost:8080/users/user1@test.com http/1.1
2017-03-21 11:33:15.516 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:15.516 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:15.516 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:15.516 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:15.516 [main] DEBUG com.stubbornjava.common.HttpClient - --> END GET
2017-03-21 11:33:15.521 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 200 OK http://localhost:8080/users/user1@test.com (4ms)
2017-03-21 11:33:15.521 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Encoding: gzip
2017-03-21 11:33:15.522 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: keep-alive
2017-03-21 11:33:15.522 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json
2017-03-21 11:33:15.522 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 96
2017-03-21 11:33:15.522 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.522 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP (encoded body omitted)
2017-03-21 11:33:15.523 [main] DEBUG c.s.e.undertow.rest.RestClient - {"email":"user1@test.com","roles":["USER"],"dateCreated":"2017-03-21"}
2017-03-21 11:33:15.524 [main] DEBUG com.stubbornjava.common.HttpClient - --> GET http://localhost:8080/users/user2@test.com http/1.1
2017-03-21 11:33:15.524 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:15.524 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:15.524 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:15.524 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:15.524 [main] DEBUG com.stubbornjava.common.HttpClient - --> END GET
2017-03-21 11:33:15.527 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 200 OK http://localhost:8080/users/user2@test.com (3ms)
2017-03-21 11:33:15.528 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Encoding: gzip
2017-03-21 11:33:15.528 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: keep-alive
2017-03-21 11:33:15.528 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json
2017-03-21 11:33:15.528 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 105
2017-03-21 11:33:15.528 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.528 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP (encoded body omitted)
2017-03-21 11:33:15.529 [main] DEBUG c.s.e.undertow.rest.RestClient - {"email":"user2@test.com","roles":["USER","ADMIN"],"dateCreated":"2017-03-21"}
2017-03-21 11:33:15.529 [main] DEBUG c.s.e.undertow.rest.RestClient -


2017-03-21 11:33:15.529 [main] DEBUG c.s.e.undertow.rest.RestClient - **** Delete Users ****
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient - --> DELETE http://localhost:8080/users/user1@test.com http/1.1
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 0
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient -
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient -
2017-03-21 11:33:15.534 [main] DEBUG com.stubbornjava.common.HttpClient - --> END DELETE (0-byte body)
2017-03-21 11:33:15.539 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 204 No Content http://localhost:8080/users/user1@test.com (4ms)
2017-03-21 11:33:15.539 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.539 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP
2017-03-21 11:33:15.539 [main] DEBUG c.s.e.undertow.rest.RestClient -


2017-03-21 11:33:15.539 [main] DEBUG c.s.e.undertow.rest.RestClient - **** Get Missing User ****
2017-03-21 11:33:15.540 [main] DEBUG com.stubbornjava.common.HttpClient - --> GET http://localhost:8080/users/user1@test.com http/1.1
2017-03-21 11:33:15.540 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:15.540 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:15.540 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:15.541 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:15.541 [main] DEBUG com.stubbornjava.common.HttpClient - --> END GET
2017-03-21 11:33:15.550 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 404 Not Found http://localhost:8080/users/user1@test.com (9ms)
2017-03-21 11:33:15.551 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Encoding: gzip
2017-03-21 11:33:15.551 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: keep-alive
2017-03-21 11:33:15.551 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json
2017-03-21 11:33:15.552 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 85
2017-03-21 11:33:15.552 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.552 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP (encoded body omitted)
2017-03-21 11:33:15.552 [main] DEBUG c.s.e.undertow.rest.RestClient - null
2017-03-21 11:33:15.552 [main] DEBUG c.s.e.undertow.rest.RestClient -


2017-03-21 11:33:15.552 [main] DEBUG c.s.e.undertow.rest.RestClient - **** Exception ****
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - --> POST http://localhost:8080/users http/1.1
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json; charset=utf-8
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 4
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - Host: localhost:8080
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: Keep-Alive
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - Accept-Encoding: gzip
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - User-Agent: okhttp/3.6.0
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient -
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - null
2017-03-21 11:33:15.554 [main] DEBUG com.stubbornjava.common.HttpClient - --> END POST (4-byte body)
2017-03-21 11:33:15.561 [main] DEBUG com.stubbornjava.common.HttpClient - <-- 500 Internal Server Error http://localhost:8080/users (7ms)
2017-03-21 11:33:15.562 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Encoding: gzip
2017-03-21 11:33:15.563 [main] DEBUG com.stubbornjava.common.HttpClient - Connection: keep-alive
2017-03-21 11:33:15.563 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Type: application/json
2017-03-21 11:33:15.563 [main] DEBUG com.stubbornjava.common.HttpClient - Content-Length: 77
2017-03-21 11:33:15.563 [main] DEBUG com.stubbornjava.common.HttpClient - Date: Tue, 21 Mar 2017 15:33:15 GMT
2017-03-21 11:33:15.563 [main] DEBUG com.stubbornjava.common.HttpClient - <-- END HTTP (encoded body omitted)
Exception in thread "main" java.lang.RuntimeException: code: 500, body: {
  "statusCode" : 500,
  "message" : "Internal Server Error"
}
  at com.stubbornjava.common.HttpClient.unknownException(HttpClient.java:69)
  at com.stubbornjava.examples.undertow.rest.RestClient.lambda$3(RestClient.java:110)
  at com.stubbornjava.examples.undertow.rest.RestClient$$Lambda$30/1990160809.get(Unknown Source)
  at org.jooq.lambda.Unchecked.lambda$supplier$37(Unchecked.java:1647)
  at org.jooq.lambda.Unchecked$$Lambda$33/1007880005.get(Unknown Source)
  at com.stubbornjava.examples.undertow.rest.RestClient.createUser(RestClient.java:112)
  at com.stubbornjava.examples.undertow.rest.RestClient.main(RestClient.java:170)

jOOλ - Unchecked

We make use of jOOλ's convenient Unchecked for ignoring IOExceptions in this code. Probably not the best idea, but it is an Example.

REST Web Protocols

Published at DZone with permission of Bill O'Neil. See the original article here.

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Comments

OkHttp Example REST Client

Jumping off the lightweight Java REST server we created in the last article, this tutorial lets us get programmatic access to our API in Java using OkHttp.

OkHttp's HttpUrl and Request

RestClient

Creating a User

Updating a User

Listing Users

Get User by Email

Delete User by Email

Example Usage

Server Log

Output

jOOλ - Unchecked

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