How do I bridge activity on a Google Apps email address to a Java program on Windows?

I need a Java program running on Windows to react to incoming email on a specific Google Apps email address.

I am not against using any sort of middleman program or language to accomplish this as easily and reliably as possible.

What are my best options?开发者_开发百科

Integrate with Google directly.

http://code.google.com/apis/gmail/oauth/

...or you can fetch email from the Gmail account using IMAP or POP3.