javafx keyboard event shortcut key

问题:

I want to add keyboard shortcut key in javafx.

i have scene and want to implement the keyboard shortcut

my code is as follows

getApplication().getScene().setOnKeyPressed(new EventHandler<KeyEvent>() {

        public void handle(KeyEvent ke) {
            if (ke.getCode() == KeyCode.ESCAPE) {
                System.out.println("Key Pressed: " + ke.getCode());
            }
        }
    });

回答1:

Events travel from the scene to the focused node (event capturing) and then back to the scene (event bubbling). Event filter are triggered during event capturing, while onKeyPressed and event handler are triggered during event bubbling. Some controls (for example TextField) consume the event, so it never comes back to the scene, i.e. event bubbling is canceled and onKeyPressed for the scene doesn't work.

To get all key pressed events use addEventFilter method:

scene.addEventFilter(KeyEvent.KEY_PRESSED, new EventHandler<KeyEvent>() {
    public void handle(KeyEvent ke) {
        if (ke.getCode() == KeyCode.ESCAPE) {
            System.out.println("Key Pressed: " + ke.getCode());
            ke.consume(); // <-- stops passing the event to next node
        }
    }
});

If you want to capture key combinations use the KeyCodeCombination class:

scene.addEventFilter(KeyEvent.KEY_PRESSED, new EventHandler<KeyEvent>() {
    final KeyCombination keyComb = new KeyCodeCombination(KeyCode.ESCAPE,
                                                          KeyCombination.CONTROL_DOWN);
    public void handle(KeyEvent ke) {
        if (keyComb.match(ke)) {
            System.out.println("Key Pressed: " + keyComb);
            ke.consume(); // <-- stops passing the event to next node
        }
    }
});

There is also the possibility to add shortcuts to the menu by setting an accelerator (see [2]).

References

• [1] http://docs.oracle.com/javafx/2/events/processing.htm
• [2] https://blog.idrsolutions.com/2014/04/tutorial-how-to-setup-key-combinations-in-javafx/

回答2:

I am not sure what you are doing with getApplication, but just to show that KeyEventHandler on Scene works, here's a demo for you.

import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class MyApp extends Application {
    public void start(Stage stage) {

        VBox root = new VBox();
        root.setAlignment(Pos.CENTER);
        Label heading = new Label("Press Key");
        Label keyPressed = new Label();
        root.getChildren().addAll(heading, keyPressed);
        Scene scene = new Scene(root, 400, 300);

        scene.setOnKeyPressed(new EventHandler<KeyEvent>() {
            public void handle(KeyEvent ke) {
                keyPressed.setText("Key Pressed: " + ke.getCode());
            }
        });

        stage.setTitle("My JavaFX Application");
        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}