Path to background in servlet

Question

//the below line is the element of my HTML form which renders the image sent by the servlet written further below.

  <img style="margin-left:91px; margin-top:-6px;" class="image" src="http://www.abcd.com/captchaServlet"> 

I generate a captcha code using the following code in java.

public class captchaServlet extends HttpServlet {


  protected void processRequest(HttpServletRequest request, 
                                HttpServletResponse response) 
                 throws ServletException, IOException {

    int width = 150;
    int height = 50;
    int charsToPrint = 6;

     String elegibleChars = "ABCDEFGHJKLMPQRSTUVWXYabcdefhjkmnpqrstuvwxy1234567890";

     char[] chars = elegibleChars.toCharArray();
StringBuffer finalString = new StringBuffer();

   for ( int i = 0; i < charsToPrint; i++ ) {
     double randomValue = Math.random();
     int randomIndex = (int) Math.round(randomValue * (chars.length - 1));
     char characterToShow = chars[randomIndex];
     finalString.append(characterToShow);
   }
   System.out.println(finalString);

    BufferedImage bufferedImage = new BufferedImage(width, height, 
                  BufferedImage.TYPE_INT_RGB);

    Graphics2D g2d = bufferedImage.createGraphics();

    Font font = new Font("Georgia", Font.BOLD, 18);
    g2d.setFont(font);

    RenderingHints rh = new RenderingHints(
           RenderingHints.KEY_ANTIALIASING,
           RenderingHints.VALUE_ANTIALIAS_ON);

    rh.put(RenderingHints.KEY_RENDERING, 
           RenderingHints.VALUE_RENDER_QUALITY);

    g2d.setRenderingHints(rh);

    GradientPaint gp = new GradientPaint(0, 0, 
    Color.BLUE, 0, height/2, Color.black, true);

    g2d.setPaint(gp);
    g2d.fillRect(0, 0, width, height);

    g2d.setColor(new Color(255, 255, 0));

    Random r = new Random();
    int index = Math.abs(r.nextInt()) % 5;
    char[] data=new String(finalString).toCharArray();
    String captcha = String.copyValueOf(data);
    int x = 0; 
    int y = 0;

    for (int i=0; i<data.length; i++) {
        x += 10 + (Math.abs(r.nextInt()) % 15);
        y = 20 + Math.abs(r.nextInt()) % 20;
        g2d.drawChars(data, i, 1, x, y);
    }

    g2d.dispose();

    response.setContentType("image/png");
    OutputStream os = response.getOutputStream();
    ImageIO.write(bufferedImage, "png", os);
    os.close();
  } 


  protected void doGet(HttpServletRequest request, 
                       HttpServletResponse response)
                           throws ServletException, IOException {
      processRequest(request, response);
  } 


  protected void doPost(HttpServletRequest request, 
                        HttpServletResponse response)
                            throws ServletException, IOException {
      processRequest(request, response);
  }
}

But in the above code background is also generated using the setPaint menthod I am guessing. I want the background to be some image from my local machine whoz URL i should be able to mention like

URL url=this.getClass().getResource("Desktop/images.jpg");
BufferedImage bufferedImage = ImageIO.read(url);

I am just writing the above two lines for making the reader understand better what the issue is. Dont want to use the exact same commands. All I want is the the background of the captcha code generated should be an image of my choice.

Answer 1

Instead of calling

g2d.setPaint(gp);
g2d.fillRect(0, 0, width, height);

You probably need to call something like:

g2d.drawImage(bufferedImage, 0, 0, null);