Back in 2009, I already a made a blogpost about some handy code which you can use in your ADF Web Application. You can say this blogspot is part 2 and here I will show you the code, I use most in my own managed Beans.
I start with FacesContext class, with this class you can use to find a JSF Component, change the Locale, get the ELContext, Add a message to your view and get the ExternalContext
The ExternalContext class, with this you can retrieve all the java init & context (web.xml) parameters, the Request & Session parameters and your web application url.
AdfFacesContext class, you can use this class for Partial Page Rendering ( PPR), get the PageFlowScope and ViewScope variables
ADFContext class, with this you can get all the memory scopes variables even the application scope variables, ELContext and the SecurityContext.
SecurityContext class, retrieve the current user and its roles.
BindingContext, BindingContainer and DCBindingContainer class. These classes are well known when you want to retrieve the ADF pagedef objects.
The last class is ControllerContext, which you can use to retrieve the exceptions