OAuth2
Spring Security OAuth2 library provides support for both the authorization code grant type (for web apps) and the implicit grant type (for single-page apps). You can also use Spring Security to protect your resources, and to configure your application as an OAuth2 resource server. The OAuth2 authentication process can be complex and time-consuming, but the Spring Security OAuth2 library makes it easy to get started by providing a set of convenient configuration classes and annotations.
Learn more about Oauth2 from the following resources: