Programmatically authenticate user with Keycloak in java

Question

I have been looking through the Keycloak documentation but cannot see how to do this. With Java, I'd like to take a valid userid and password and then generate a token. How can I do this?

Answer 1

--EDIT 2018-08-31--

You can use the Authorization Client Java API. Once you have created an AuthzClient object, you can pass the username and password to the AuthzClient#authorization(username, password) or AuthzClient#obtainAccessToken(username, password) method to authenticate the user and get the access token (and/or ID token in the first case):

// create a new instance based on the configuration defined in keycloak-authz.json
AuthzClient authzClient = AuthzClient.create();

// send the authorization request to the server in order to
// obtain an access token granted to the user
AccessTokenResponse response = authzClient.obtainAccessToken("alice", "alice");

On a side note, if possible, you'd rather reuse one of the Keycloak Java Adapters to cover more features, such as other authentication methods (the user is typically redirected to Keycloack WUI where you can enforce very flexible authentication and authorization policies).