Launching JavaFX 2 with Spring Boot

Question

I am trying to create new application with JavaFX 2 and Spring Boot, but so far my simple app (like hello world) isn't running because of "root is null" in MainPaneController.

MainPaneController class:

public class MainPaneController implements Initializable {

    public static final String VIEW = "/fxml/Scene.fxml";

    @FXML
    private Node root;

    @FXML
    private Label label;

    @PostConstruct
    public void init() {
    }

    public Node getRoot() {
        return root;
    }

    @FXML
    private void handleButtonAction(ActionEvent event) {
        System.out.println("You clicked me!");
        label.setText("Hello World!");
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
    }

}

Main class FxBootApplication:

@SpringBootApplication
public class FxBootApplication extends Application {

    private static String[] args;

    @Override
    public void start(final Stage stage) throws Exception {
        //Parent root = FXMLLoader.load(getClass().getResource("/fxml/Scene.fxml"));
        // Bootstrap Spring context here.
        ApplicationContext context = SpringApplication.run(FxBootApplication.class, args);

        MainPaneController mainPaneController = context.getBean(MainPaneController.class);

        Scene scene = new Scene((Parent) mainPaneController.getRoot()); // error here

        //Scene scene = new Scene(root);
        //scene.getStylesheets().add("/styles/Styles.css");
        stage.setTitle("JavaFX and Maven");
        stage.setScene(scene);
        stage.show();
    }

    /**
     * The main() method is ignored in correctly deployed JavaFX application.
     * main() serves only as fallback in case the application can not be
     * launched through deployment artifacts, e.g., in IDEs with limited FX
     * support. NetBeans ignores main().
     *
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        FxBootApplication.args = args;
        launch(args);
    }

}

ApplicationConfiguration class:

@Configuration
public class ApplicationConfiguration {

    @Bean
    public MainPaneController mainPaneController() throws IOException {
        MainPaneController mpc = (MainPaneController) loadController(MainPaneController.VIEW);
        return mpc;
    }

    public <T> T loadController(String url) throws IOException {
        try (InputStream fxmlStream = getClass().getResourceAsStream(url)) {
            FXMLLoader loader = new FXMLLoader(getClass().getResource(url));
            //FXMLLoader.load(url);
            loader.load(fxmlStream);
            return loader.getController();
        }
    }

}

Error is while I am trying to get root for Scene by controller.getRoot();

I followed the solution proposed here -> JavaFX fxml - How to use Spring DI with nested custom controls? but eventually is not working for me at all. Should I somehow initialize this root before?

Did you try to add @Import(ApplicationConfiguration.class) to FxBootApplication — Orest, Jan 28 '16 at 12:03
I will try this one, but I think that problem might be with loading this controller. It should get the root initialized, but it does not, do not know why yet. — Infinito, Jan 28 '16 at 12:32

dzim · Answer 1 · 2017-02-22T09:41:12.250

Unfortunately I don't find the link to the solution, that works for me, anymore... But: I have the code, which I tested to some extend.

First you need your Application class:

package eu.dzim.yatafx;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

import eu.dzim.yatafx.model.app.ApplicationModel;
import eu.dzim.yatafx.spring.service.FXMLLoaderService;
import eu.dzim.yatafx.util.Utils;
import eu.dzim.yatafx.util.res.StringResource;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

@Configuration
@EnableAutoConfiguration
@ComponentScan
public class YataFXApplication extends Application implements CommandLineRunner {

    private static final Logger LOG = LogManager.getLogger(FileSyncFXApplication.class);

    @Override
    public void run(String... args) {
        // something to call prior to the real application starts?
    }

    private static String[] savedArgs;

    // locally stored Spring Boot application context
    private ConfigurableApplicationContext applicationContext;

    // we need to override the FX init process for Spring Boot
    @Override
    public void init() throws Exception {

        // set Thread name
        Thread.currentThread().setName("main");

        // LOG.debug("Init JavaFX application");
        applicationContext = SpringApplication.run(getClass(), savedArgs);
        applicationContext.getAutowireCapableBeanFactory().autowireBean(this);
    }

    // ... and close our context on stop of the FX part
    @Override
    public void stop() throws Exception {
        // LOG.debug("Stop JavaFX application");
        super.stop();
        applicationContext.close();
    }

    protected static void launchApp(Class<? extends FileSyncFXApplication> appClass, String[] args) {
        FileSyncFXApplication.savedArgs = args;
        Application.launch(appClass, args);
    }

    @Autowired
    private FXMLLoaderService mFXMLLoaderService;

    @Autowired
    private ApplicationModel mApplicationModel;

    @Override
    public void start(Stage primaryStage) {

        // set Thread name
        Thread.currentThread().setName("main-ui");

        try {
            FXMLLoader loader = mFXMLLoaderService.getLoader(Utils.getFXMLResource("Root"), StringResource.getResourceBundle());

            Pane root = loader.load();

            Scene scene = new Scene(root, 1200, 800);
            scene.getStylesheets().add("/eu/dzim/filesyncfx/ui/application.css");

            primaryStage.setScene(scene);
            primaryStage.setOnCloseRequest(windowEvent -> {

                LOG.debug("tear down JavaFX application");
                // mApplicationModel.setLoggedIn(!mLoginService.logout());

                // orderly shut down FX
                Platform.exit();

                // But: there might still be a daemon thread left over from OkHttp (some async dispatcher)
                // so assume everything is fine and call System.exit(0)
                System.exit(0);
            });

            primaryStage.show();

        } catch (Exception e) {
            LOG.error(e.getMessage(), e);
        }
    }

    public static void main(String[] args) throws Exception {

        // SpringApplication.run(SampleSimpleApplication.class, args);

        savedArgs = args;
        Application.launch(FileSyncFXApplication.class, args);
    }
}

I used org.springframework.boot:spring-boot-starter-parent:1.3.3.RELEASE as the base.

Note the FXMLLoaderService interface I autowired here:

package eu.dzim.yatafx.spring.service;

import java.net.URL;
import java.util.ResourceBundle;

import javafx.fxml.FXMLLoader;

public interface FXMLLoaderService {

    FXMLLoader getLoader();

    FXMLLoader getLoader(URL location);

    FXMLLoader getLoader(URL location, ResourceBundle resourceBundle);
}

The implementation looks like this:

package eu.dzim.yatafx.spring.service.impl;

import java.net.URL;
import java.util.ResourceBundle;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

import eu.dzim.yatafx.spring.service.FXMLLoaderService;
import javafx.fxml.FXMLLoader;
import javafx.util.Callback;

@Component
@Scope("singleton")
public class FXMLLoaderServiceImpl implements FXMLLoaderService {

    private static final Logger LOG = LogManager.getLogger(FXMLLoaderServiceImpl.class);

    @Autowired
    private ConfigurableApplicationContext context;

    @PostConstruct
    private void postConstruct() {
        LOG.debug("PostConstruct: set up " + getClass().getName());
    }

    @Override
    public FXMLLoader getLoader() {
        FXMLLoader loader = new FXMLLoader();
        loader.setControllerFactory(new Callback<Class<?>, Object>() {
            @Override
            public Object call(Class<?> param) {
                return context.getBean(param);
            }
        });
        return loader;
    }

    @Override
    public FXMLLoader getLoader(URL location) {
        FXMLLoader loader = new FXMLLoader(location);
        loader.setControllerFactory(new Callback<Class<?>, Object>() {
            @Override
            public Object call(Class<?> param) {
                return context.getBean(param);
            }
        });
        return loader;
    }

    @Override
    public FXMLLoader getLoader(URL location, ResourceBundle resourceBundle) {
        FXMLLoader loader = new FXMLLoader(location, resourceBundle);
        loader.setControllerFactory(new Callback<Class<?>, Object>() {
            @Override
            public Object call(Class<?> param) {
                return context.getBean(param);
            }
        });
        return loader;
    }

    @PreDestroy
    private void preDestroy() {
        LOG.debug("PreDestroy: tear down " + getClass().getName());
    }
}

The usage is already displayed in the Application class: Just @Autowire the service and create the sub-views from there. Since I rely almost exclusivly on FXML, this one is importand to me, since I want to use all that nice DI stuff in my Controllers.

Best example is the global Application, wich holds some JavaFX properties I attach to in the controller classes.

While the shown application is more a stub (the application and the FXML service), I had a fun project where I used this approach in concurrency to a parallel developed Web application, that was RESTing on a "Micro"service I developed at work.

Hope the code is enough an example to get it to work on your side. Please just ask, if you have more questions.

Cheers, Daniel

Edit: I think the mistake in your code is simply the part in the FXML service. I have this injected ConfigurableApplicationContext which I use to create the controller from. You would need a ControllerFactory for this.

There are some third party samples to assist with JavaFX and Spring Boot integration:

This one was useful for me: `applicationContext.getAutowireCapableBeanFactory().autowireB‌ean(this);` Tutorials I used that were showing how to combine SpringBootApplication, @Autowired fields and JavaFX were missing this step. Thanks! — alwi, Jan 05 '17 at 12:59
As far as I know, this method is useful to inject members __afterwards__ - when the class is already created. On the contrary `context.getBean(class)` creates the bean and injects the members in one line of code. But in the end, it only matters, that you have some means, to get the job done. Right? :-) — dzim, Jan 06 '17 at 07:44
@jewelsea - thanks for your three links. I especially liked the third one. And I've added my own example-repo, just for the sake of it... — dzim, Feb 22 '17 at 09:43

Launching JavaFX 2 with Spring Boot

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