XHTMLPanel panel = new XHTMLPanel();
       
        try {
            panel.setDocument(new File("c:\\file.html"));
        } catch (Exception e) {
            e.printStackTrace(); 
        }       
        JFrame frame = new JFrame();       
        frame.getContentPane().add(panel);
        frame.pack();
        frame.setSize(1500, 1200);
        BufferedImage image=new BufferedImage(frame.getWidth(),frame.getHeight(),BufferedImage.TYPE_INT_ARGB);
        Graphics2D graphics2D=image.createGraphics();
        frame.paint(graphics2D);
        try {
            ImageIO.write(image,"jpg",new File("c:\\image_test.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        frame.setVisible(false);
        frame.dispose();

frame.setVisible(true);