One of the great improvement in Java EE 5 and beyond it is the introduction of CDI (Context and Dependency Injection). CDI is used for injecting dependencies among a lot of other things like events, interceptors, … and can be used in POJOs.
In some cases instead of injecting other objects (as a dependency injection), you want to inject a value from a properties file into a class that needs to be configured externally.
I have written an example in Tomitribe community zone: https://github.com/tomitribe/community/tree/master/injecting-properties
We keep learning,
Sora ni akogarete sora wo kakete yuku, Ano ko no inochi wa hikoukigumo (The Wind Rises - Joe Hisaishi, Yumi Arai)