FXML切り替えによる画面遷移

MementoWeaver開発記(3)
JavaFXでの画面遷移の実現方法について、JavaFX SamplesのFXML-LoginDemoを手本としてみる。
サンプルのソースはこんな感じ(重要な箇所のみを一部抜粋)。

まずはアプリケーションクラス(Main)側。

package demo;
// snip!

public class Main extends Application {
    // snip!
    @Override
    public void start(Stage primaryStage) {
        try {
            stage = primaryStage;
            stage.setTitle("FXML Login Sample");
            stage.setMinWidth(MINIMUM_WINDOW_WIDTH);
            stage.setMinHeight(MINIMUM_WINDOW_HEIGHT);
            gotoLogin();
            primaryStage.show();
        } catch (Exception ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    // snip!

    private void gotoProfile() {
        try {
            ProfileController profile = (ProfileController) replaceSceneContent("Profile.fxml");
            profile.setApp(this);
        } catch (Exception ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    private void gotoLogin() {
        try {
            LoginController login = (LoginController) replaceSceneContent("Login.fxml");
            login.setApp(this);
        } catch (Exception ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    private Initializable replaceSceneContent(String fxml) throws Exception {
        FXMLLoader loader = new FXMLLoader();
        InputStream in = Main.class.getResourceAsStream(fxml);
        loader.setBuilderFactory(new JavaFXBuilderFactory());
        loader.setLocation(Main.class.getResource(fxml));
        AnchorPane page;
        try {
            page = (AnchorPane) loader.load(in);
        } finally {
            in.close();
        } 
        Scene scene = new Scene(page, 800, 600);
        stage.setScene(scene);
        stage.sizeToScene();
        return (Initializable) loader.getController();
    }
}

次は、コントローラクラス(LoginController)側

/*
 * Copyright (c) 2008, 2012 Oracle and/or its affiliates.
 * All rights reserved. Use is subject to license terms.
 *
 * This file is available and licensed under the following license:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the distribution.
 *  - Neither the name of Oracle Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package demo;

// snip!
public class LoginController extends AnchorPane implements Initializable {

    // snip!
    public void setApp(Main application){
        this.application = application;
    }
    
    @Override
    public void initialize(URL location, ResourceBundle resources) {
        errorMessage.setText("");
        userId.setPromptText("demo");
        password.setPromptText("demo");
        
    }
    
    public void processLogin(ActionEvent event) {
        if (application == null){
            // We are running in isolated FXML, possibly in Scene Builder.
            // NO-OP.
            errorMessage.setText("Hello " + userId.getText());
        } else {
            if (!application.userLogging(userId.getText(), password.getText())){
                errorMessage.setText("Username/Password is incorrect");
            }
        }
    }
}

要するにすごくざっくりと言うと、こんな流れか。

MainはLogin.fxmlをロードしてシーンコンテンツを置き換える(replaceSceneContent)
Mainは置き換えたシーンのコントローラクラス(この場合はLoginController)をLoaderから得る
Mainはコントローラクラス(この場合はLoginController)に自身を登録する
LoginControllerは自身のイベントハンドリングの中で、登録されたMainオブジェクトを使用する(Mainオブジェクトをアプリケーション内の共有オブジェクトのコンテナとして使っている)。

コントローラクラス側でAnchorPaneをextendsしていたり、Initializableをimplementsしている理由はまだ理解できていないが、細かいことは後で考える(笑)。

ひとまずMainMenu→InstallMaterialの画面遷移が実装できたのでGitHubにcommitしておく。