clock.java

这是JFrame的一些例子(chapter4)。可以参考一下。想要做GUI的人不妨看一看

/**
	Clock
*/
package clock;

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import java.io.*;
import java.util.*;

import javax.swing.*;
import javax.swing.border.*;

public class Clock 
	extends    JButton
	implements Customizer, Externalizable, Runnable
{

	protected PropertyChangeSupport m_helper;
	protected boolean  m_digital = false;
	protected Calendar m_calendar;
	protected Dimension m_preffSize;

	public Clock()
	{
		m_calendar = Calendar.getInstance();
		m_helper = new PropertyChangeSupport(this);

		Border br1 = new EtchedBorder(EtchedBorder.RAISED, 
			Color.white, new Color(128, 0, 0));
		Border br2 = new MatteBorder(4, 4, 4, 4, Color.red);
		setBorder(new CompoundBorder(br1, br2));

		setBackground(Color.white);
		setForeground(Color.black);

		(new Thread(this)).start();
	}

	public void writeExternal(ObjectOutput out)   
		throws IOException
	{
		out.writeBoolean(m_digital);
		out.writeObject(getBackground());
		out.writeObject(getForeground());
		out.writeObject(getPreferredSize());
	}

	public void readExternal(ObjectInput in)
		throws IOException, ClassNotFoundException
	{
		setDigital(in.readBoolean());
		setBackground((Color)in.readObject());
		setForeground((Color)in.readObject());
		setPreferredSize((Dimension)in.readObject());
	}

	public Dimension getPreferredSize()
	{
		if (m_preffSize != null)
			return m_preffSize;
		else
			return new Dimension(50, 50);
	}
	
	public void setPreferredSize(Dimension preffSize)
	{
		m_preffSize = preffSize;
	}

	public Dimension getMinimumSize()
	{
		return getPreferredSize();
	}

	public Dimension getMaximumSize()
	{
		return getPreferredSize();
	}

	public void setDigital(boolean digital)
	{
		m_helper.firePropertyChange("digital",
			new Boolean(m_digital), 
			new Boolean(digital));
		m_digital = digital;
		repaint();
	}

	public boolean getDigital()
	{
		return m_digital;
	}

	public void addPropertyChangeListener(
		PropertyChangeListener lst)
	{
		if (m_helper != null)
			m_helper.addPropertyChangeListener(lst);
	}

	public void removePropertyChangeListener(
		PropertyChangeListener lst)
	{
		if (m_helper != null)
			m_helper.removePropertyChangeListener(lst);
	}

	public void setObject(Object bean) {}

	public void paintComponent(Graphics g)
	{
                super.paintComponent(g);
                Color colorRetainer = g.getColor();

		g.setColor(getBackground());
		g.fillRect(0, 0, getWidth(), getHeight());
		getBorder().paintBorder(this, g, 0, 0, getWidth(), getHeight());

		m_calendar.setTime(new Date());	// get current time
		int hrs = m_calendar.get(Calendar.HOUR_OF_DAY);
		int min = m_calendar.get(Calendar.MINUTE);

		g.setColor(getForeground());
		if (m_digital)
		{
			String time = ""+hrs+":"+min;
			g.setFont(getFont());
			FontMetrics fm = g.getFontMetrics();
			int y = (getHeight() + fm.getAscent())/2;
			int x = (getWidth() - fm.stringWidth(time))/2;
			g.drawString(time, x, y);
		}
		else
		{
			int x = getWidth()/2;
			int y = getHeight()/2;
			int rh = getHeight()/4;
			int rm = getHeight()/3;

			double ah = ((double)hrs+min/60.0)/6.0*Math.PI;
			double am = min/30.0*Math.PI;

			g.drawLine(x, y, (int)(x+rh*Math.sin(ah)), 
				(int)(y-rh*Math.cos(ah)));
			g.drawLine(x, y, (int)(x+rm*Math.sin(am)), 
				(int)(y-rm*Math.cos(am)));
		}

                g.setColor(colorRetainer);
	}

	public void run()
	{
		while (true)
		{
			repaint();
			try
			{
				Thread.sleep(30*1000);
			}
			catch(InterruptedException ex) { break; }
		}
	}
}