quelque choise comme ca!!
public void saveFrameAsJepg(JFrame frame, File jpeg) {
BufferedImage image = new BufferedImage(frame.getWidth(),
frame.getHeight(),
BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = image.createGraphics();
frame.paint(g2);
g2.dispose();
try {
ImageIO.write(image, "JPEG", jpeg);
} catch (Exception e) { }
}