How to separate interface from implementation in Grails services?

Question

I was wondering if it\'s possible to create a service interface on Grails and I can\'t find a proper way of doing it. This explanation isn\'t satisfactory, since it seems to mix

Answer 1

The best solution I found for this is using Spring bean aliases. Basically you need to:

1) Create an interface in src/groovy ( MyService.groovy )

2) Inject your service wherever you need it:

class MyController {
    MyService myService
}

3) Create your regular services implementing that interface ( ImplOneService.groovy, ImplTwoService.groovy )

4) Add an entry to resources.groovy where you define which implementation to use (eventually, testing for environment, or anything else you need):

beans = {
    if (...development, useFTP, etc...) {
        springConfig.addAlias 'myService', 'ImplOneService'
    } else {
        springConfig.addAlias 'myService', 'ImplTwoService'
    }
}

Complete sources here

My comments: Using interfaces in groovy really seems like some kind of "I want to stick with some java stuff I'm more comfortable with". In this case, strong-typing. But it's exactly the nice part of groovy saying "No worries, you can keep the java way if you want".