Spring fun

Example for blog post: http://zoltanaltfatter.com/2016/10/22/spring-application-context-from-multi-modules/

The project contains two client modules (client-with-java-config, client-with-xml-config) which both depend on the legacy-module which uses Spring XML config.

The legacy-module defines a GreetingService with an implementation (DutchGreetingService) and also a client of this GreetingService which is GreetingServiceClient

Now in the two client modules we depend on the legacy-module and use the GreetingServiceClient but we would like to override the GreetingService with its own implementation.

Client with XML Config

In the client-with-xml-config module we construct the application context like this:

ApplicationContext applicationContext = new ClassPathXmlApplicationContext(
                "classpath*:/META-INF/spring/module-context.xml",
                "classpath:/client-context.xml"
);

The ordering of the resources matter. In the above scenario the DutchGreetingService from legacy-module will be overridden by the HungarianGreetingSerivce since both have the same id greetingService.

Client with Java Config

In the client-with-java-config module the default is the HungarianGreetingService which is always overridden by the DutchGreetingService from legacy-module. We cannot control the ordering of the resources when the combined application context is created.

@SpringBootApplication
@ImportResource(value = "classpath*:/META-INF/spring/module-context.xml")