This project is a minimal but functional OAuth2 Authorization Server (token issuer) and Resource Server (protected API). (You could split the two roles across two applications if you preferred.) It uses Spring Boot to provide an embedded servlet container and for defaulting a load of configuration, so you should be up and running with it very quickly.

You need Java (1.8 or better) and Maven (3.0.5 or better):

$ mvn clean install
$ mvn spring-boot:run
...
<app starts and listens on port 8080>

Here are some curl commands to use to get started:

$ curl -H "Accept: application/json" my-trusted-client@localhost:8080/oauth/token -d "grant_type=password&username=user&password=password"

$ curl -H "Authorization: Bearer $TOKEN" localhost:8080/
Hello World