7

我正在用 java 制作一个非常简单的乒乓球游戏，我正在使用 KeyListener 来做这个。我想要它，所以当用户按下键盘上的左右键时，乒乓球块会朝那个方向移动。这是一个足够简单的任务，但我发现当用户按住键时，块移动一次，停止一小段时间，然后继续移动直到用户释放键。我注意到当您尝试按住计算机上的字母键时会发生这种情况。如果我尝试按住“a”键，计算机将执行以下操作：

[暂停] aaaaaaaaaaaaaaa

有什么办法可以禁用这种口吃，因为它妨碍了我的小游戏流畅的游戏玩法。快速修复将不胜感激。

4

3 回答 3

9

我最初有一个关于 Key Bindings 的答案，但经过一些测试后，我发现他们仍然有同样的口吃问题。

不要依赖操作系统的重复率。每个平台都可能不同，用户也可以自定义它。

而是使用计时器来安排事件。您在 keyPressed 上启动 Timer，在 keyReleased 上停止 Timer。

import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.util.Map;
import java.util.HashMap;
import javax.imageio.ImageIO;
import javax.swing.*;

public class KeyboardAnimation implements ActionListener
{
    private final static String PRESSED = "pressed ";
    private final static String RELEASED = "released ";
    private final static Point RELEASED_POINT = new Point(0, 0);

    private JComponent component;
    private Timer timer;
    private Map<String, Point> pressedKeys = new HashMap<String, Point>();

    public KeyboardAnimation(JComponent component, int delay)
    {
        this.component = component;

        timer = new Timer(delay, this);
        timer.setInitialDelay( 0 );
    }

    public void addAction(String keyStroke, int deltaX, int deltaY)
    {
//      InputMap inputMap = component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
        InputMap inputMap = component.getInputMap();
        ActionMap actionMap = component.getActionMap();

        String pressedKey = PRESSED + keyStroke;
        KeyStroke pressedKeyStroke = KeyStroke.getKeyStroke( pressedKey );
        Action pressedAction = new AnimationAction(keyStroke, new Point(deltaX, deltaY));
        inputMap.put(pressedKeyStroke, pressedKey);
        actionMap.put(pressedKey, pressedAction);

        String releasedKey = RELEASED + keyStroke;
        KeyStroke releasedKeyStroke = KeyStroke.getKeyStroke( releasedKey );
        Action releasedAction = new AnimationAction(keyStroke, RELEASED_POINT);
        inputMap.put(releasedKeyStroke, releasedKey);
        actionMap.put(releasedKey, releasedAction);
    }

    private void handleKeyEvent(String keyStroke, Point moveDelta)
    {
        //  Keep track of which keys are pressed

        if (RELEASED_POINT == moveDelta)
            pressedKeys.remove( keyStroke );
        else
            pressedKeys.put(keyStroke, moveDelta);

        //  Start the Timer when the first key is pressed

        if (pressedKeys.size() == 1)
        {
            timer.start();
        }

        //  Stop the Timer when all keys have been released

        if (pressedKeys.size() == 0)
        {
            timer.stop();
        }
    }

    //  Invoked when the Timer fires

    public void actionPerformed(ActionEvent e)
    {
        moveComponent();
    }

    //  Move the component to its new location

    private void moveComponent()
    {
        int componentWidth = component.getSize().width;
        int componentHeight = component.getSize().height;

        Dimension parentSize = component.getParent().getSize();
        int parentWidth  = parentSize.width;
        int parentHeight = parentSize.height;

        //  Calculate new move

        int deltaX = 0;
        int deltaY = 0;

        for (Point delta : pressedKeys.values())
        {
            deltaX += delta.x;
            deltaY += delta.y;
        }


        //  Determine next X position

        int nextX = Math.max(component.getLocation().x + deltaX, 0);

        if ( nextX + componentWidth > parentWidth)
        {
            nextX = parentWidth - componentWidth;
        }

        //  Determine next Y position

        int nextY = Math.max(component.getLocation().y + deltaY, 0);

        if ( nextY + componentHeight > parentHeight)
        {
            nextY = parentHeight - componentHeight;
        }

        //  Move the component

        component.setLocation(nextX, nextY);
    }

    private class AnimationAction extends AbstractAction implements ActionListener
    {
        private Point moveDelta;

        public AnimationAction(String keyStroke, Point moveDelta)
        {
            super(PRESSED + keyStroke);
            putValue(ACTION_COMMAND_KEY, keyStroke);

            this.moveDelta = moveDelta;
        }

        public void actionPerformed(ActionEvent e)
        {
            handleKeyEvent((String)getValue(ACTION_COMMAND_KEY), moveDelta);
        }
    }

    public static void main(String[] args)
    {
        JPanel contentPane = new JPanel();
        contentPane.setLayout( null );

        Icon dukeIcon = null;

        try
        {
            dukeIcon = new ImageIcon( "dukewavered.gif" );
//          dukeIcon = new ImageIcon( ImageIO.read( new URL("http://duke.kenai.com/iconSized/duke4.gif") ) );
        }
        catch(Exception e)
        {
            System.out.println(e);
        }

        JLabel duke = new JLabel( dukeIcon );
        duke.setSize( duke.getPreferredSize() );
        duke.setLocation(100, 100);
        contentPane.add( duke );

        KeyboardAnimation navigation = new KeyboardAnimation(duke, 24);
        navigation.addAction("LEFT", -3,  0);
        navigation.addAction("RIGHT", 3,  0);
        navigation.addAction("UP",    0, -3);
        navigation.addAction("DOWN",  0,  3);

        navigation.addAction("A", -5,  0);
        navigation.addAction("S",  5,  0);
        navigation.addAction("Z",  0, -5);
        navigation.addAction("X",  0,  5);
        navigation.addAction("V",  5,  5);

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
//      frame.getContentPane().add(new JTextField(), BorderLayout.SOUTH);
        frame.getContentPane().add(contentPane);
        frame.setSize(600, 600);
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
    }

}

此代码在 Windows 上进行了测试，其中事件的顺序为 keyPressed、keyPressed、keyPressed...keyReleased。

但是，我认为在 Mac（或 Unix）上，事件的顺序是 keyPressed、keyReleased、keyPressed、keyReleased ......所以我不确定这段代码是否会比你当前的代码更好。

于 2013-05-02T02:12:37.580 回答
5
  1. 您应该使用键绑定，因为它们解决了大多数与焦点相关的问题，并且通常更灵活......
  2. 您需要定义一个标志来指示何时按下某个键。按下时，您不应执行任何其他任务...

举些例子...

用简单的例子更新

在大多数游戏中，您应该对“状态变化”做出反应，而不是对实际的关键事件做出反应。这意味着实际改变状态的事件可以是可变的（想想自定义键）

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class SinglePressKeyBinding {

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

    public SinglePressKeyBinding() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JLabel message;

        private boolean spacedOut = false;

        public TestPane() {
            message = new JLabel("Waiting");
            setLayout(new GridBagLayout());
            add(message);

            InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
            ActionMap am = getActionMap();

            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, false), "space-pressed");
            im.put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, true), "space-released");

            am.put("space-pressed", new AbstractAction() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    if (spacedOut) {
                        message.setText("I'm ignoring you");
                    } else {
                        spacedOut = true;
                        message.setText("Spaced out");
                    }
                }
            });
            am.put("space-released", new AbstractAction() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    spacedOut = false;
                    message.setText("Back to earth");
                }
            });

        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }
}
于 2013-05-02T01:34:57.070 回答
1

一个好主意是为要跟踪的键设置布尔值，然后在 keypressed 事件上激活其中一个布尔值，并在释放键时停用它。它将消除按键的滞后并允许多次按键！

于 2013-08-24T17:06:15.863 回答