keycloak offline token with Java

Question

I am using authentication of users in Java 8 against Keycloak, with the Keycloak adapter API for Java.

In this case, the class KeycloakBuilder (keycloak-admin-client-6.0.0.jar) builds a Keycloak instance to perform authentication operations.

how can I request an offline token rather than a normal Bearer token using this API?

Have not found parameter or way to request it. I need tokens with 1 month expiration time, which cannot get unless change the "SSO Session Max" field, but I don´t want this to affect other Clients or users in the same Realm / client.

Answer 1

I post a possible solution using keycloak-authz-client library instead.

As stated by @Philipp , it is also necessary that the user you log in with has the role offline_access.

public String login(String username, String password) {
    String authServerUrl = "http://localhost:18080/auth"; // Your keycloak auth endpoint
    String realm = "realm"; // Realm
    String clientId = "client"; // Client
    Map<String, Object> clientCredentials = new LinkedHashMap<String, Object>();
    clientCredentials.put("secret", "clientSecret"); // Client secret (Access Type: Confidential)
    
    Configuration configuration = new Configuration(
        authServerUrl,
        realm,
        clientId,
        clientCredentials,
        null
    );
    
    AuthzClient authzClient = AuthzClient.create(configuration);
    
    AuthorizationRequest request = new AuthorizationRequest();
    request.setScope("offline_access");
    
    AuthorizationResponse response = authzClient.authorization(username, password).authorize(request);
    
    return response.getRefreshToken(); // response.getToken() returns the bearer token
}