This great primer for Contexts and Dependency Injection covers the need for it and a simple implementation in a Java EE environment that focuses on injecting properties.
In the first of this two-part article, we look at the roles involved in authentication a request via OAuth, the protocol flow, and how authorization is granted to a user.
Here's an introduction to logging with Log4j. If you aren't familiar with it already, take a look at what it offers and how to configure it for your Java projects.