通过关键竞标进行JLabel移动

与大多数事情一样，开始看看教程“
如何使用键绑定”，几乎所有答案都将基于这些内容。

您可以做这样简单的事情…

import com.sun.glass.events.KeyEvent;import java.awt.Dimension;import java.awt.EventQueue;import java.awt.event.ActionEvent;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 Test {    public static void main(String[] args) {        new Test();    }    public Test() {        EventQueue.invokeLater(new Runnable() { @Override public void run() {     try {         UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());     } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {         ex.printStackTrace();     }     Jframe frame = new Jframe("Testing");     frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);     frame.add(new TestPane());     frame.pack();     frame.setLocationRelativeTo(null);     frame.setVisible(true); }        });    }    public interface Movable {        public void changeLocation(int xDelta, int yDelta);    }    public class TestPane extends JPanel implements Movable {        private JLabel player;        public TestPane() { setLayout(null); player = new JLabel("X"); player.setSize(player.getPreferredSize()); add(player); setupKeyBindings();        }        @Override        public Dimension getPreferredSize() { return new Dimension(200, 200);        }        protected void setupKeyBindings() { InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW); ActionMap am = getActionMap(); im.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0), "up"); im.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0), "down"); im.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0), "left"); im.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0), "right"); int xDelta = player.getWidth(); int yDelta = player.getHeight(); am.put("up", new MoveAction(this, 0, -yDelta)); am.put("down", new MoveAction(this, 0, yDelta)); am.put("left", new MoveAction(this, -xDelta, 0)); am.put("right", new MoveAction(this, xDelta, 0));        }        @Override        public void changeLocation(int xDelta, int yDelta) { int xPos = player.getX() + xDelta; int yPos = player.getY() + yDelta; if (xPos + player.getWidth() > getWidth()) {     xPos = getWidth() - player.getWidth(); } else if (xPos < 0) {     xPos = 0; } if (yPos + player.getHeight() > getHeight()) {     yPos = getHeight() - player.getHeight(); } else if (xPos < 0) {     yPos = 0; } player.setLocation(xPos, yPos);        }    }    public class MoveAction extends AbstractAction{        private Movable movable;        private int xDelta;        private int yDelta;        public MoveAction(Movable movable, int xDelta, int yDelta) { this.movable = movable; this.xDelta = xDelta; this.yDelta = yDelta;        }        @Override        public void actionPerformed(ActionEvent e) { movable.changeLocation(xDelta, yDelta);        }    }}

正如我反复告诉您或您的同班同学一样，您不应该以这种方式使用组件。相反，您应该遵循自定义的绘画路线，从长远来看，它将为您提供更大的灵活性和更少的问题。

import com.sun.glass.events.KeyEvent;import java.awt.Color;import java.awt.Dimension;import java.awt.EventQueue;import java.awt.FontMetrics;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.Rectangle;import java.awt.event.ActionEvent;import javax.swing.AbstractAction;import javax.swing.ActionMap;import javax.swing.InputMap;import javax.swing.Jframe;import javax.swing.JPanel;import javax.swing.KeyStroke;import javax.swing.UIManager;import javax.swing.UnsupportedLookAndFeelException;public class Test {    public static void main(String[] args) {        new Test();    }    public Test() {        EventQueue.invokeLater(new Runnable() { @Override public void run() {     try {         UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());     } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {         ex.printStackTrace();     }     Jframe frame = new Jframe("Testing");     frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);     frame.add(new TestPane());     frame.pack();     frame.setLocationRelativeTo(null);     frame.setVisible(true); }        });    }    public interface Movable {        public void changeLocation(int xDelta, int yDelta);    }    public class TestPane extends JPanel implements Movable {        private Rectangle player;        public TestPane() { String text = "X"; FontMetrics fm = getFontMetrics(getFont()); int width = fm.stringWidth(text); int height = fm.getHeight(); player = new Rectangle(0, 0, width, height); setupKeyBindings();        }        @Override        public Dimension getPreferredSize() { return new Dimension(200, 200);        }        protected void setupKeyBindings() { InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW); ActionMap am = getActionMap(); im.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0), "up"); im.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0), "down"); im.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0), "left"); im.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0), "right"); int xDelta = player.width; int yDelta = player.height; am.put("up", new MoveAction(this, 0, -yDelta)); am.put("down", new MoveAction(this, 0, yDelta)); am.put("left", new MoveAction(this, -xDelta, 0)); am.put("right", new MoveAction(this, xDelta, 0));        }        @Override        public void changeLocation(int xDelta, int yDelta) { int xPos = player.x + xDelta; int yPos = player.y + yDelta; if (xPos + player.width > getWidth()) {     xPos = getWidth() - player.width; } else if (xPos < 0) {     xPos = 0; } if (yPos + player.height > getHeight()) {     yPos = getHeight() - player.height; } else if (xPos < 0) {     yPos = 0; } player.setLocation(xPos, yPos); repaint();        }        @Override        protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); g2d.setColor(Color.RED); g2d.draw(player); FontMetrics fm = g2d.getFontMetrics(); g2d.drawString("X", player.x, player.y + fm.getAscent()); g2d.dispose();        }    }    public class MoveAction extends AbstractAction {        private Movable movable;        private int xDelta;        private int yDelta;        public MoveAction(Movable movable, int xDelta, int yDelta) { this.movable = movable; this.xDelta = xDelta; this.yDelta = yDelta;        }        @Override        public void actionPerformed(ActionEvent e) { movable.changeLocation(xDelta, yDelta);        }    }}

您还应该适当地使用布局管理器。这些可以保护您的头发和时间。

有关更多详细信息，请参见在容器中布置组件