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This blog post fleshes out a previous, much briefer post on adding Spring Framework to the JavaFX and Kotlin mix. I took my original multi-controller application and converted all the JavaFX controllers into Spring Beans.  All the beans are initialised in a configuration class, and allowed me to refactor the controllers to use constructor based injection.

Spring Controller Initialisation

All the controllers are created by Spring in a configuration class. Also the EventBus is also a bean and injected into all the controllers.

@Configuration
open class ApplicationConfig {
   @Bean
   open fun applicationController(fileListController: FileListController,
                                  filePropertiesController: FilePropertiesController,
                                  fileDataController: FileDataController): ApplicationController {
      return ApplicationController(fileListController, fileDataController, filePropertiesController)
   }

   @Bean
   open fun eventBus(): EventBus {
      return EventBus()
   }

   @Bean
   open fun fileDataController(eventBus: EventBus): FileDataController {
      return FileDataController(eventBus)
   }

   @Bean
   open fun fileListController(eventBus: EventBus): FileListController {
      return FileListController(eventBus)
   }

   @Bean
   open fun filePropertiesController(eventBus: EventBus): FilePropertiesController {
      return FilePropertiesController(eventBus)
   }
}

So the Application Controller is now much simpler, taking all the other controllers as constructor arguments.

class ApplicationController(private val fileListController: FileListController, private val fileDataController: FileDataController, private val filePropertiesController: FilePropertiesController) {
...
}

Application Startup

Application startup now needs to create a Spring Application Context and inject the application controller into the FXML Loader.

class Main : Application() {
   private val context: AnnotationConfigApplicationContext = AnnotationConfigApplicationContext(ApplicationConfig::class.java)

   @Throws(Exception::class)
   override fun start(primaryStage: Stage) {
      val controller = context.getBean("applicationController") as ApplicationController
      val loader = FXMLLoader(javaClass.getResource("/springkotlin.fxml"))
      loader.setController(controller)
      ...
   }
}

And that’s it! The full source code is here.