Image seems not loading in servlet running in tomcat 4 ... (win xp)

Question

This servlet basically takes a images file do some scaling then send out as outputstream.
BUT the image dun since to load ... i keep getting a -1 for the width n height of the image .... seems that image cant load in tomcat....
Is it something wrong wif my code or is there a bug in tomcat....
Can someone help thanks
This is the servlet code:
import javax.servlet.http.*;
import javax.servlet.*;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.*;
import java.net.*;
import java.awt.*;
import java.awt.image.*;
public class ImageOperater extends HttpServlet
public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException
{ System.out.println("Start of post");
OutputStream out = null;
try{
out = res.getOutputStream();
catch(Exception e)
e.printStackTrace();
System.out.println("Start of imageprocessing");
//image processing
Image img = Toolkit.getDefaultToolkit().getImage("images/peppers.png");
ImageFilter imf = new CropImageFilter(0,0,200,200);
ImageProducer ip = new FilteredImageSource(img.getSource(),imf);
img = Toolkit.getDefaultToolkit().createImage(ip);
img =img.getScaledInstance(500,-1,Image.SCALE_AREA_AVERAGING);
//image processing finish
//check if the image is fully loaded
System.out.println("Start of image loading");
MediaTracker mediaTracker = new MediaTracker(new Container());
mediaTracker.addImage(img, 0);
try{
mediaTracker.waitForID(0);
System.out.println(mediaTracker.checkAll());
System.out.println("thread sleep");
Thread.sleep(1000);
catch(Exception e)
e.printStackTrace();
try{
mediaTracker.waitForID(0);
System.out.println(mediaTracker.checkAll());
System.out.println("thread sleep");
Thread.sleep(1000);
catch(Exception e)
e.printStackTrace();
//image fully loaded
System.out.println("Start of buffered image ");
System.out.println("width"+img.getWidth(null)+" Height "+img.getHeight(null));
//preparing the buffered image to be send
BufferedImage bimg = new BufferedImage(img.getWidth(null),img.getHeight(null),BufferedImage.TYPE_INT_RGB);
Graphics gr = bimg.getGraphics();
gr.drawImage(img, 0, 0, null);
gr.dispose();
//finished preparing
//ig = Toolkit.getDefaultToolkit().createImage(bimg.getSource());
System.out.println("Start of sending");
//send out to client
try{
ImageIO.write((RenderedImage)bimg,"png",new File("c:\\test.png"));
ImageIO.write((RenderedImage)bimg,"png",out);
catch(Exception e)
e.printStackTrace();
try{
out.flush();
out.close();
catch(Exception e)
e.printStackTrace();
System.out.println("post ended");
but if the same code is put into an applet it works ... thw getWidth() and getHeight() returns the correct value:
Image img = Toolkit.getDefaultToolkit().getImage("images/peppers.png");
ImageFilter imf = new CropImageFilter(0,0,200,200);
ImageProducer ip = new FilteredImageSource(img.getSource(),imf);
img = Toolkit.getDefaultToolkit().createImage(ip);
img =img.getScaledInstance(500,-1,Image.SCALE_AREA_AVERAGING);
//image processing finish
//check if the image is fully loaded
System.out.println("Start of image loading");
MediaTracker mediaTracker = new MediaTracker(new Container());
mediaTracker.addImage(img, 0);
try{
mediaTracker.waitForID(0);
System.out.println(mediaTracker.checkAll());
System.out.println("thread sleep");
Thread.sleep(1000);
catch(Exception e)
e.printStackTrace();
try{
mediaTracker.waitForID(0);
System.out.println(mediaTracker.checkAll());
System.out.println("thread sleep");
Thread.sleep(1000);
catch(Exception e)
e.printStackTrace();
//image fully loaded
System.out.println("Start of buffered image ");
System.out.println("width"+img.getWidth(null)+" Height "+img.getHeight(null));
//preparing the buffered image to be send
BufferedImage bimg = new BufferedImage(img.getWidth(null),img.getHeight(null),BufferedImage.TYPE_INT_RGB);
Graphics gr = bimg.getGraphics();
gr.drawImage(img, 0, 0, null);
gr.dispose();
//finished preparing
//ig = Toolkit.getDefaultToolkit().createImage(bimg.getSource());
System.out.println("Start of sending");
//send out to client
try{
ImageIO.write((RenderedImage)bimg,"png",new File("c:\\test.png"));

Answer 1

hi ganttan
first you have to make sure your server is running xwindow. in most cases a linux/apache server does not run it by default. then there is a much simpler approach of scaling images with a servlet:
Iterator readers = ImageIO.getImageReadersByFormatName("gif");
ImageReader reader = (ImageReader)readers.next();
ImageInputStream iis = ImageIO.createImageInputStream(new File(path));
reader.setInput(iis, true);
ImageReadParam param = reader.getDefaultReadParam();
param.setSourceRenderSize(new Dimension(width, height));
BufferedImage thumbnail = reader.read(0, param);
ImageIO.write(thumbnail, "gif", response.getOutputStream());
however this does not work for jpeg images. use setSourceSampling() instead of setSourceRenderSize() in this case but unfortunately it's limited and you can not scale to any size.