如何在控制器类中的 JavaFX 应用程序中交换屏幕？

如果一个JavaFX项目中有3个文件； FXML 文件、FXML 控制器和应用程序类；控制器如何响应按钮单击（效果非常好）并更改该单击上的屏幕（通常是通过stage.setScreen()）？我没有参考阶段（它被传递给应用程序类的start(Stage)).

应用样本：

public class JavaFXApplication4 extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("Sample.fxml"));

        Scene scene = new Scene(root);

        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) {
        launch(args);
    }
}

FXML 示例：

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" prefHeight="200.0" prefWidth="320.0"  xmlns:fx="http://javafx.com/fxml" fx:controller="javafxapplication4.SampleController">
  <children>
  <Button id="button" fx:id="nextScreen" layoutX="126.0" layoutY="90.0" onAction="#handleButtonAction" text="Next Screen" />
  <Label fx:id="label" layoutX="126.0" layoutY="120.0" minHeight="16.0" minWidth="69.0" />
  </children>
</AnchorPane>

控制器示例：

public class SampleController implements Initializable {

    @FXML
    private Label label;

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

        // Here I want to swap the screen!
    }

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

@FXML
private void handleButtonAction(ActionEvent event) {
    System.out.println("You clicked me!");
    label.setText("Hello World!");
    //Here I want to swap the screen!

    Stage stageTheEventSourceNodeBelongs = (Stage) ((Node)event.getSource()).getScene().getWindow();
    // OR
    Stage stageTheLabelBelongs = (Stage) label.getScene().getWindow();
    // these two of them return the same stage
    // Swap screen
    stage.setScene(new Scene(new Pane()));
}