我强烈建议你看看KeyBindings，他们更习惯这种情况，更关心焦点相关的问题。这篇关于Motion Using the Keyboard的帖子，可能一定会让您感兴趣，关注的主题:-)
编辑 ：
这是一个来自帮助的小程序：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class KeyBindingExample
{
private DrawingBoard contentPane;
/*
* There variables will simply
* decide how much the square
* will move with click key press,
* in this case I have set this to
* 1 (inside the constructor).
* brakes will simply tell whether
* the square will move or not in
* a given direction.
*/
private int speed;
private int brakes;
public KeyBindingExample() {
speed = 5;
brakes = 0;
}
private void displayGUI()
{
JFrame frame = new JFrame("Swing Worker Example");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
contentPane = new DrawingBoard(10, 10, Color.BLUE.darker());
addBindingsToBoard();
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private void addBindingsToBoard() {
/*
* Since, when UP Arrow is pressed, that means, the square
* can move vertically upwards, hence, the square will move
* along Y-Axis that too in the negative direction of the
* same, though along X-Axis the square will move nowhere,
* hence, we passing 0 and -1, since we want to add the
* current location (say square is at present at 50, 50),
* now after UP Arrow key event, square will be at (50, 49);
*/
putBindingsFor(contentPane, KeyStroke.getKeyStroke("UP"),
"UP Arrow Key", brakes, -speed);
/*
* When RIGHT Arrow is pressed, the square is suppose to
* move horizontally, along the X-Axis, in the positive
* direction towards the RIGHT. Hence +1 change along X-Axis
* and no change along Y-Axis, i.e. from (50, 49), the square
* will now move to (51, 49), that's why we passing (+1, 0)
*/
putBindingsFor(contentPane, KeyStroke.getKeyStroke("RIGHT"),
"RIGHT Arrow Key", speed, brakes);
/*
* When DOWN Arrow is pressed, the square is suppose to
* move vertically, along the Y-Axis, in the positive
* direction towards the BOTTOM. Hence no change along X-Axis
* and +1 change along Y-Axis, i.e. from (51, 49), the square
* will now move to (51, 50), that's why we passing (0, +1)
*/
putBindingsFor(contentPane, KeyStroke.getKeyStroke("DOWN"),
"DOWN Arrow Key", brakes, +speed);
/*
* When LEFT Arrow is pressed, the square is suppose to
* move horizontally, along the X-Axis, in the negative
* direction towards the LEFT side. Hence -1 change along X-Axis
* and no change along Y-Axis, i.e. from (51, 50), the square
* will now move to (50, 50), that's why we passing (-1, 0).
* The square will atlast come to it's initial position.
*/
putBindingsFor(contentPane, KeyStroke.getKeyStroke("LEFT"),
"LEFT Arrow Key", -speed, brakes);
}
private void putBindingsFor(JComponent comp,
KeyStroke keyStroke, String value, final int moveX, final int moveY) {
comp.getInputMap().put(keyStroke, value);
comp.getActionMap().put(value, new AbstractAction() {
@Override
public void actionPerformed(ActionEvent ae) {
contentPane.setValues(moveX, moveY);
}
});
}
public static void main(String[] args)
{
Runnable runnable = new Runnable()
{
@Override
public void run()
{
new KeyBindingExample().displayGUI();
}
};
EventQueue.invokeLater(runnable);
}
}
class DrawingBoard extends JPanel {
private int x;
private int y;
private int width;
private int height;
private Color rectColor;
public DrawingBoard(int x, int y, Color rColor) {
setOpaque(true);
this.x = x;
this.y = y;
rectColor = rColor;
width = height = 10;
}
public void setValues(int deltaX, int deltaY) {
System.out.format("Firstly X : %d\tY : %d%n", x, y);
repaint(x, y, width, height);
/*
* Whatever values are passed from above, i.e.
* say on Left ARROW, we passing (-1, 0),
* therefore deltaX will be -1 and deltaY will
* be 0. Now whatever the current value of X is
* we are simply adding deltaX to that value
* and the same goes for deltaY as well.
* Now since the value for x and y is updated
* after these two statements below, we checking
* that whether these two updated values lies
* within the bounds of our board or not.
* If they are, then we simply calling repaint,
* to draw the square at this new location, else
* we simply bring back the previous values of
* x and y to their previous state.
*/
x += deltaX;
y += deltaY;
if ((x + width) <= getWidth() && (y + height) <= getHeight()
&& x >= 0 && y >= 0) {
System.out.format("Later X : %d\tY : %d%n", x, y);
repaint(x, y, width, height);
}
else {
x -= deltaX;
y -= deltaY;
System.out.format("Later X : %d\tY : %d%n", x, y);
repaint(x, y, width, height);
}
}
/*
* Make this a customary habbit of overridding
* this method whenever you have to override
* any JComponent, instead of calling
* setPreferredSize(...).
*/
@Override
public Dimension getPreferredSize() {
return (new Dimension(100, 100));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(rectColor);
g.fillRect(x, y, width, height);
}
}