how to achieve single sign on in java for google apps

I am new to java also at Google Apps, I am using Ecl开发者_开发知识库ipse.

I want to create a simple app that perform SSO in java with google.

i have done the demo app that will host over google app engine, it is working fine using google plugin how can i do it with my app running on my server.

thanks

Look at GAE: Configuring Your App's Authentication article. After configuring it you can check user using The Users Java API invoking:

UserService userService = UserServiceFactory.getUserService();
User user = userService.getCurrentUser();

This is the simplest way. There are many other. Like using OpenID described here: http://code.google.com/p/gwt-gae-book/wiki/Authentication

You can also create your own auth servlet filter wchich redirects users to userService.createLoginURL URL if needed.