import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public class ImageProducerServlet extends HttpServlet
{
  private static final String CONTENT_TYPE = "image/jpeg";

  public void init(ServletConfig config) throws ServletException
  {
    super.init(config);
  }

  public void doGet(HttpServletRequest request, HttpServletResponse response)
                                                throws ServletException, IOException
  {
    response.setContentType(CONTENT_TYPE);
    OutputStream out = response.getOutputStream();
    (new ImageCreator()).writeImageStream(out);
    out.close();
  }
}

import java.awt.image.*;
import java.awt.*;
import com.sun.image.codec.jpeg.*;
import java.io.*;

public class ImageCreator 
{
  public void writeImageStream(OutputStream out) throws IOException
  {
    BufferedImage bi = new BufferedImage(80,40,BufferedImage.TYPE_INT_RGB);
    Graphics g = bi.getGraphics();
    g.setColor(Color.white);
    g.fillRect(1,1,78,38);
    g.setColor(Color.black);

    Font f = new Font("Arial", Font.PLAIN, 12);
    g.setFont(f);
    g.drawString("String", 20,30);
    JPEGImageEncoder jie = JPEGCodec.createJPEGEncoder(out);
    jie.encode(bi);
  }
}