Does Grails use Spring Dependency Injection by default

An additional question: What is service layer in Grails app?开发者_StackOverflow

Thanks

Yes, Grails uses Spring Dependency Injection by default. Grails is in fact Spring at the core of it all.

Your second question, "what is a service layer" is best described as singleton instances of classes that serve as a layer of abstraction and encapsulation of business logic.