如何让玩家在2D JavaFX游戏中自由移动？

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.stage.Stage;
import javafx.util.Duration;
import javafx.animation.TranslateTransition;

public class Game extends Application {
    private static final int PLAYER_SIZE = 50;
    private static final int PLAYER_SPEED = 5;
    
    private ImageView playerView;
    private TranslateTransition translateTransition;
    
    @Override
    public void start(Stage primaryStage) {
        Group root = new Group();
        Scene scene = new Scene(root, 800, 600);
        
        // 创建角色图像
        Image playerImage = new Image("player.png");
        playerView = new ImageView(playerImage);
        playerView.setFitWidth(PLAYER_SIZE);
        playerView.setFitHeight(PLAYER_SIZE);
        playerView.setX(scene.getWidth() / 2 - PLAYER_SIZE / 2);
        playerView.setY(scene.getHeight() / 2 - PLAYER_SIZE / 2);
        
        // 创建角色移动动画
        translateTransition = new TranslateTransition(Duration.millis(100), playerView);
        translateTransition.setCycleCount(1);
        
        root.getChildren().add(playerView);
        
        // 添加键盘事件监听器
        scene.setOnKeyPressed(this::handleKeyPressed);
        scene.setOnKeyReleased(this::handleKeyReleased);
        
        primaryStage.setScene(scene);
        primaryStage.setTitle("2D JavaFX Game");
        primaryStage.show();
    }
    
    private void handleKeyPressed(KeyEvent event) {
        KeyCode keyCode = event.getCode();
        
        // 根据按下的键盘按键来控制角色移动
        switch (keyCode) {
            case UP:
                moveUp();
                break;
            case DOWN:
                moveDown();
                break;
            case LEFT:
                moveLeft();
                break;
            case RIGHT:
                moveRight();
                break;
        }
    }
    
    private void handleKeyReleased(KeyEvent event) {
        KeyCode keyCode = event.getCode();
        
        // 松开键盘按键停止移动
        switch (keyCode) {
            case UP:
            case DOWN:
                stopVerticalMove();
                break;
            case LEFT:
            case RIGHT:
                stopHorizontalMove();
                break;
        }
    }
    
    private void moveUp() {
        translateTransition.stop();
        translateTransition.setToY(playerView.getY() - PLAYER_SPEED);
        translateTransition.play();
    }
    
    private void moveDown() {
        translateTransition.stop();
        translateTransition.setToY(playerView.getY() + PLAYER_SPEED);
        translateTransition.play();
    }
    
    private void moveLeft() {
        translateTransition.stop();
        translateTransition.setToX(playerView.getX() - PLAYER_SPEED);
        translateTransition.play();
    }
    
    private void moveRight() {
        translateTransition.stop();
        translateTransition.setToX(playerView.getX() + PLAYER_SPEED);
        translateTransition.play();
    }
    
    private void stopVerticalMove() {
        translateTransition.stop();
        translateTransition.setToY(playerView.getY());
        translateTransition.play();
    }
    
    private void stopHorizontalMove() {
        translateTransition.stop();
        translateTransition.setToX(playerView.getX());
        translateTransition.play();
    }
    
    public static void main(String[] args) {
        launch(args);
    }
}