Custom OAuth API with SpringSocial. Google OAuth2.

GoogleApi.java

public interface Google extends ApiBinding {

  String API_URL_BASE = "https://www.googleapis.com/oauth2/v2/";

  UserOperations userOperations();
}

public interface UserOperations {

  GoogleProfile getUserProfile();
}

public class GoogleProfile implements Serializable {
  private final String id;
  private String name;
  private String givenName;
  private String familyName;
  private String gender;
  private Locale locale;
  private String link;
  private String pictureUrl;

  public GoogleProfile(final String id) {
    this.id = id;
  }

  public String getId() {
    return id;
  }

  public String getName() {
    return name;
  }

  public String getGivenName() {
    return givenName;
  }

  public String getFamilyName() {
    return familyName;
  }

  public String getGender() {
    return gender;
  }

  public Locale getLocale() {
    return locale;
  }

  public String getLink() {
    return link;
  }

  public String getPictureUrl() {
    return pictureUrl;
  }
}

GoogleBindings.java

public class GoogleModule extends SimpleModule {
  public GoogleModule() {
    super("GoogleModule", new Version(1, 0, 0, "alpha-1"));
  }

  @Override
  public void setupModule(final SetupContext context) {
    context.setMixInAnnotations(GoogleProfile.class, GoogleProfileMixin.class);
  }
}


@JsonIgnoreProperties(ignoreUnknown = true)
abstract class GoogleProfileMixin {

  @JsonCreator
  GoogleProfileMixin(
      @JsonProperty("id") String id) {
  }

  @JsonProperty("name")
  private String name;

  @JsonProperty("given_name")
  private String givenName;

  @JsonProperty("family_name")
  private String familyName;

  @JsonProperty("gender")
  private String gender;

  @JsonProperty("locale")
  private Locale locale;

  @JsonProperty("link")
  private String link;

  @JsonProperty("picture")
  private String pictureUrl;
}

GoogleImpl.java

public class GoogleTemplate extends AbstractOAuth2ApiBinding implements Google {
  private UserOperations userOperations;

  public GoogleTemplate() {
    initialize();
  }

  public GoogleTemplate(final String accessToken) {
    super(accessToken);
    initialize();
  }

  public UserOperations userOperations() {
    return userOperations;
  }

  @Override
  protected MappingJacksonHttpMessageConverter getJsonMessageConverter() {
    final MappingJacksonHttpMessageConverter converter = super.getJsonMessageConverter();
    final ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.registerModule(new GoogleModule());
    converter.setObjectMapper(objectMapper);
    return converter;
  }

  private void initialize() {
    userOperations = new UserTemplate(getRestTemplate(), isAuthorized());
  }
}


public class UserTemplate implements UserOperations {
  private static final LinkedMultiValueMap<String, String> EMPTY_PARAMETERS = new LinkedMultiValueMap<String, String>();

  private final RestTemplate template;
  private final boolean authorized;

  public UserTemplate(final RestTemplate template, final boolean authorized) {
    this.template = template;
    this.authorized = authorized;
  }

  public GoogleProfile getUserProfile() {
    requireAuthorization();
    return template.getForObject(buildUri("userinfo"), GoogleProfile.class);
  }

  protected void requireAuthorization() {
    if (!authorized) {
      throw new MissingAuthorizationException();
    }
  }

  protected URI buildUri(final String path) {
    return buildUri(path, EMPTY_PARAMETERS);
  }

  protected URI buildUri(final String path, final String parameterName, final String parameterValue) {
    final MultiValueMap<String, String> parameters = new LinkedMultiValueMap<String, String>();
    parameters.set(parameterName, parameterValue);
    return buildUri(path, parameters);
  }

  protected URI buildUri(final String path, final MultiValueMap<String, String> parameters) {
    return URIBuilder.fromUri(Google.API_URL_BASE + path).queryParams(parameters).build();
  }
}

GoogleServices.java

public class GoogleServiceProvider extends AbstractOAuth2ServiceProvider<Google> {

  public GoogleServiceProvider(final String clientId, final String clientSecret) {
    super(new GoogleOAuth2Template(clientId, clientSecret));
  }

  @Override
  public Google getApi(final String accessToken) {
    return new GoogleTemplate(accessToken);
  }
}


public class GoogleOAuth2Template extends OAuth2Template {
  private static final String AUTHORIZE_URL = "https://accounts.google.com/o/oauth2/auth";
  private static final String ACCESS_TOKEN_URL = "https://accounts.google.com/o/oauth2/token";

  public GoogleOAuth2Template(final String clientId, final String clientSecret) {
    super(clientId, clientSecret, AUTHORIZE_URL, ACCESS_TOKEN_URL);
  }
}