Web client

RESThub Web client module aims to give you an easy way to request other REST webservices. It is based on AsyncHttpClient and provides a client API wrapper and OAuth2 support.

In order to limit conflicts it has no dependency on Spring, but only on:

AsyncHttpClient 1.8.13 documentation and Javadoc
Jackson 2.4.2 (documentation)

Configuration

In order to use it in your project, add the following snippet to your pom.xml:

<dependency>
    <groupId>org.resthub</groupId>
    <artifactId>resthub-web-client</artifactId>
    <version>2.2.0</version>
</dependency>

Usage

You can use resthub web client in a synchronous or asynchronous way. The synchronous API is easy to use, but blocks the current Thread until the remote server sends the full Response.

// One-liner version
Sample s = httpClient.url("http//...").jsonPost(new Sample("toto")).resource(Sample.class);

// List<T> and Page<T> use TypeReference due to Java type erasure issue
List<Sample> p = httpClient.url("http//...").jsonGet().resource(new TypeReference<List<Sample>>() {});
Page<Sample> p = httpClient.url("http//...").jsonGet().resource(new TypeReference<Page<Sample>>() {});

Asynchronous API is quite the same, every HTTP request returns a Future <Response> object. Just call get() on this object in order to make the call synchronous. The Future.get() method can throw Exceptions, so the method call should be surrounded by a try/catch or let the exceptions bubble up.

// 4 lines example
Client httpClient = new Client();
Future<Response> fr = httpClient.url("http//...").asyncJsonPost(new Sample("toto"));
// do some computation while we're waiting for the response...

// calling .get() makes the code synchronous again!
Sample s = httpClient.url("http//...").asyncJsonPost(new Sample("toto")).get().resource(Sample.class);

Because the remote web server sometimes responds 4xx (client error) and 5xx (server error) HTTP status codes, RESThub HTTP Client wraps those error statuses and throws specific runtime exceptions.

OAuth 2.0 integration

Here is an example of a simple OAuth2 support

String username = "test";
String password = "t&5t";
String clientId = "app1";
String clientSecret = "";
String accessTokenUrl = "http://.../oauth/token";

Client httpClient = new Client().setOAuth2(username, password, accessTokenUrl, clientId, clientSecret);
String result = httpClient.url("http://.../api/sample").get().getBody();

You can also use a specific OAuth2 configuration. For example, you can override the HTTP Header used to send the OAuth token.

OAuth2Config.Builder builder = new OAuth2Config.Builder();
builder.setAccessTokenEndpoint("http://.../oauth/token")
       .setUsername("test").setPassword("t&5t")
       .setClientId("app1").setClientSecret("")
       .setOAuth2Scheme("OAuth"); // override default OAuth HTTP Header name

Client httpClient = new Client().setOAuth2Builder(builder);
String result = httpClient.url("http://.../api/sample").get().getBody();