It is very often that current user's username is required in UCM service. Username of the user executing the service can be retrieved using below code :
import java.util.Properties;
import intradoc.shared.UserData;
import intradoc.server.Service;
private String getCurrentUsername(Service service) {
UserData userData = service.getUserData();
Properties properties = userData.getProperties();
String userName = userData.getProperty("dName");
return userName;
}
Enjoy