JOAuth is a free and open-source Java library that implements the OAuth 1 (final) and OAuth 2 (draft 10-draft 16, draft 22).
JOAuth provides a controller for handling the OAuth communication flow between the client and service provider.
Being developed using Java, JOAuth is a cross-platform library which can be used on any operating system that comes with Java support (e.g. Mac OS X, Windows, Linux).
Detailed instructions on how to install and use the JOAuth utility on your Mac are available HERE.