我有这个 JavaFX 代码，它打印按下了哪个键。
package keyboardexample;
import java.util.Iterator;
import java.util.List;
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.SimpleBooleanProperty;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public final class KeyboardExample extends Application {
@Override
public void start(final Stage stage) {
final Keyboard keyboard = new Keyboard(new Key(KeyCode.A),
new Key(KeyCode.S),
new Key(KeyCode.D),
new Key(KeyCode.F));
final Scene scene = new Scene(new Group(keyboard.createNode()));
stage.setScene(scene);
stage.setTitle("Keyboard Example");
stage.show();
}
public static void main(final String[] args) {
launch(args);
}
private static final class Key {
private final KeyCode keyCode;
private final BooleanProperty pressedProperty;
public Key(final KeyCode keyCode) {
this.keyCode = keyCode;
this.pressedProperty = new SimpleBooleanProperty(this, "pressed");
}
public KeyCode getKeyCode() {
return keyCode;
}
public boolean isPressed() {
return pressedProperty.get();
}
public void setPressed(final boolean value) {
pressedProperty.set(value);
}
public Node createNode() {
final StackPane keyNode = new StackPane();
keyNode.setFocusTraversable(true);
installEventHandler(keyNode);
final Rectangle keyBackground = new Rectangle(50, 50);
keyBackground.fillProperty().bind(
Bindings.when(pressedProperty)
.then(Color.RED)
.otherwise(Bindings.when(keyNode.focusedProperty())
.then(Color.LIGHTGRAY)
.otherwise(Color.WHITE)));
keyBackground.setStroke(Color.BLACK);
keyBackground.setStrokeWidth(2);
keyBackground.setArcWidth(12);
keyBackground.setArcHeight(12);
final Text keyLabel = new Text(keyCode.getName());
keyLabel.setFont(Font.font("Arial", FontWeight.BOLD, 20));
keyNode.getChildren().addAll(keyBackground, keyLabel);
return keyNode;
}
private void installEventHandler(final Node keyNode) {
// handler for enter key press / release events, other keys are
// handled by the parent (keyboard) node handler
final EventHandler<KeyEvent> keyEventHandler =
new EventHandler<KeyEvent>() {
public void handle(final KeyEvent keyEvent) {
if (keyEvent.getCode() == KeyCode.ENTER) {
setPressed(keyEvent.getEventType()
== KeyEvent.KEY_PRESSED);
keyEvent.consume();
}
}
};
keyNode.setOnKeyPressed(keyEventHandler);
keyNode.setOnKeyReleased(keyEventHandler);
}
}
private static final class Keyboard {
private final Key[] keys;
public Keyboard(final Key... keys) {
this.keys = keys.clone();
}
public Node createNode() {
final HBox keyboardNode = new HBox(6);
keyboardNode.setPadding(new Insets(6));
final List<Node> keyboardNodeChildren = keyboardNode.getChildren();
for (final Key key : keys) {
keyboardNodeChildren.add(key.createNode());
}
installEventHandler(keyboardNode);
return keyboardNode;
}
private void installEventHandler(final Parent keyboardNode) {
// handler for key pressed / released events not handled by
// key nodes
final EventHandler<KeyEvent> keyEventHandler =
new EventHandler<KeyEvent>() {
public void handle(final KeyEvent keyEvent) {
final Key key = lookupKey(keyEvent.getCode());
if (key != null) {
key.setPressed(keyEvent.getEventType()
== KeyEvent.KEY_PRESSED);
keyEvent.consume();
}
}
};
keyboardNode.setOnKeyPressed(keyEventHandler);
keyboardNode.setOnKeyReleased(keyEventHandler);
keyboardNode.addEventHandler(KeyEvent.KEY_PRESSED,
new EventHandler<KeyEvent>() {
public void handle(
final KeyEvent keyEvent) {
handleFocusTraversal(
keyboardNode,
keyEvent);
}
});
}
private Key lookupKey(final KeyCode keyCode) {
for (final Key key : keys) {
if (key.getKeyCode() == keyCode) {
return key;
}
}
return null;
}
private static void handleFocusTraversal(final Parent traversalGroup,
final KeyEvent keyEvent) {
final Node nextFocusedNode;
switch (keyEvent.getCode()) {
case LEFT:
nextFocusedNode =
getPreviousNode(traversalGroup,
(Node) keyEvent.getTarget());
keyEvent.consume();
break;
case RIGHT:
nextFocusedNode =
getNextNode(traversalGroup,
(Node) keyEvent.getTarget());
keyEvent.consume();
break;
default:
return;
}
if (nextFocusedNode != null) {
nextFocusedNode.requestFocus();
}
}
private static Node getNextNode(final Parent parent,
final Node node) {
final Iterator<Node> childIterator =
parent.getChildrenUnmodifiable().iterator();
while (childIterator.hasNext()) {
if (childIterator.next() == node) {
return childIterator.hasNext() ? childIterator.next()
: null;
}
}
return null;
}
private static Node getPreviousNode(final Parent parent,
final Node node) {
final Iterator<Node> childIterator =
parent.getChildrenUnmodifiable().iterator();
Node lastNode = null;
while (childIterator.hasNext()) {
final Node currentNode = childIterator.next();
if (currentNode == node) {
return lastNode;
}
lastNode = currentNode;
}
return null;
}
}
}
你能告诉我如何打印按下了哪些组合键吗？例如这样的：CTL + L、Alt + J、K 等。