利用panel放背景圖

JPanel panel = new JPanel()

{
protected void paintComponent(Graphics g)
{

// g.drawImage(ic.getImage(), 0, 0, null);

// Scale image to size of component
Dimension d = getSize();
g.drawImage(ic.getImage(), 0, 0, d.width, d.height, null);

// Fix the image position in the scroll pane

// Point p = scrollPane.getViewport().getViewPosition();
// g.drawImage(icon.getImage(), p.x, p.y, null);

super.paintComponent(g);
}
};
panel.setOpaque( false );
panel.setPreferredSize( new Dimension(400, 400) );
getContentPane().add( panel);

JButton button = new JButton( "Hello" );
panel.add( button );
panel.setBounds(getBounds());