StackHolder - Jakub Kubrynski

After my last article there were some questions about how Java configuration work in details, and we can extend it to suite our needs. So I'll try to answer those question in this post :) Heart of Spring java configuration mechanism are  @Configuration classes. That's the place where we can define all properties of our Spring context. Assuming that we lean our application on annotations (which should be true if we want to use java config) we create beans using  @Component annotation (with derivatives like  @Repository , @Service and @Controller ). Varying annotations apply for different layers: @Component generic for any compoenents @Repository persistence layer @Service service layer @Controller presentation layer

Few years ago majority of us were used to write XML config files everywhere, to setup even simple Java EE application. Today using Java or Groovy to configure projects is becoming preferred way - you just need to take a look at Gradle or functionalities introduced in further versions of the Spring Framework to gen up on this. Now I'll deal with configuring Spring contexts for web application. Java EE provides ServletContainerInitializer interface, which allows libraries to be notified of a web application startup. Since Spring 3.1 we have SpringServletContainerInitializer class which handles WebApplicationInitializer by instantiating all found classes implementing this interface, sorting them basing on @Order annotation (non-annotated classes gets the highest possible order, so they are processed at the end) and invoking onStartup() method.

I'm currently working on a project where we use Spring Framework 4.0 and Spock for testing. Unit testing in Spock is really great, but there are some lacks in integration testing - especially in mocking Spring beans. Our requirement is to start up Spring context but with particular bean replaced with mock. The easiest part we had do implement is just regular Spring test specification: @ContextConfiguration( classes = [GatewayConfig, PaymentServiceConfig]) class PaymentServiceSpecIT extends Specification { final String CLIENT_ID = "54321" @Inject PaymentService paymentService def "Should return auth token"() { when: def token = paymentService.getAuthToken(CLIENT_ID) then: token } }