这个例子]非常好用…
public class TestClock { public static void main(String[] args) { new TestClock(); } public TestClock() { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException ex) { } catch (InstantiationException ex) { } catch (IllegalAccessException ex) { } catch (UnsupportedLookAndFeelException ex) { } Jframe frame = new Jframe(); frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); frame.setLayout(new BorderLayout()); frame.add(new ClockPane()); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } }); } protected class ClockPane extends JPanel { public ClockPane() { Timer timer = new Timer(1000, new ActionListener() { @Override public void actionPerformed(ActionEvent e) { repaint(); } }); timer.setRepeats(true); timer.setCoalesce(false); timer.start(); } @Override public Dimension getPreferredSize() { return new Dimension(200, 200); } protected Point getPointTo(float angle) { int x = Math.round(getWidth() / 2); int y = Math.round(getHeight() / 2); double rads = Math.toRadians(angle); // This is an arbitrary amount, you will need to correct for this // I'm working of a width of 200 pixels, so that makes the radius // 100... int radius = 100; // Calculate the outter point of the line int xPosy = Math.round((float) (x + Math.cos(rads) * radius)); int yPosy = Math.round((float) (y - Math.sin(rads) * radius)); return new Point(xPosy, yPosy); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); g2d.setColor(Color.RED); Calendar cal = Calendar.getInstance(); int seconds = cal.get(Calendar.SECOND); float angle = -(360f * (seconds / 60f)); angle += 90; // Correct for 0 being out to the right instead of up Point p = getPointTo(angle); int x = getWidth() / 2; int y = getHeight() / 2; g2d.drawLine(x, y, p.x, p.y); FontMetrics fm = g2d.getFontMetrics(); String text = Integer.toString(seconds); g2d.drawString(text, getWidth() - fm.stringWidth(text), getHeight() - fm.getHeight() + fm.getAscent()); g2d.dispose(); } }}
