Servlets and image processing with GNU/Linux
Lionel Peron
This servlet can display an image if it run under MS NT server. But it does
not work under GNU/Linux RedHat 6.0 server.
Does anybody knows about this problem ?
Is it possible to a servlet to read a jpeg image into a frame, modify it,
and then return an encoded jpg stream as response with Linux.
Regards.
Lionel.
Code :
import javax.swing.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class JpegDisplay extends HttpServlet {
File file = new File("/home/mon_image.jpg");
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
ServletOutputStream out = res.getOutputStream();
ImageIcon imgIcon = new ImageIcon(this.getFileToByteArray(file));
res.setContentType("image/jpeg");
out.write(this.getFileToByteArray(file));
}
private byte[] getFileToByteArray(File pFile)
{
byte[] tmpBuffer = null;
if (pFile!=null)
{
FileInputStream fileStream = null;
try{
fileStream = new FileInputStream( pFile );
} catch (java.io.FileNotFoundException e) {
System.err.println("WARNING : File not found");
}
tmpBuffer = new byte[ (int)pFile.length() ];
try{
fileStream.read(tmpBuffer);
}catch (java.io.IOException e) {
tmpBuffer = null;
System.err.println("WARNING : Impossible to translate file
in byte[]");
}
}
return tmpBuffer;
}
}
error sous linux :
java.lang.NoClassDefFoundError: sun/awt/motif/MToolkit at
org.apache.jserv.JServConnection.processRequest(JServConnection.java:327)
at org.apache.jserv.JServConnection.run(JServConnection.java:197)
at java.lang.Thread.run(Thread.java:479)
Jon Skeet
> Hello,
> This servlet can display an image if it run under MS NT server. But it does
> not work under GNU/Linux RedHat 6.0 server.
> Does anybody knows about this problem ?
> Is it possible to a servlet to read a jpeg image into a frame, modify it,
> and then return an encoded jpg stream as response with Linux.
I suspect this is due to the servlet not having an X-server to connect
to. If you can set the DISPLAY environment variable in the shell that the
servlet runs in, you should be able to run an X server (such as Xvfb) for
Java to "talk to". This whole problem is being fixed in JDK 1.4, btw.
--
Jon Skeet - sk...@pobox.com
http://www.pobox.com/~skeet/
Lionel Peron
And sorry : This problem was solved by Richard Hallier in January (see
after)
It works fine ! Thanks to Richard too ;-)
However, I can't understand why there is no reaction by Sun : A servlet
running better with Microsoft than Linux ! My god !
----------------------------------------------------------------------
Subject: Re: Problems with images in servlets (classes not found)
From: "=C1sta Herd=EDs Hall" <a...@hi.is>
Date: Wed, 26 Jan 2000 10:59:21 -0000
I just wanted to let you know that I have gotten this to work, finally,
thanks to your answers. What I ended up doing was as follows:
1. Add the line wrapper.env=3DDISPLAY=3Dlocalhost:0 to my jserv.properti=
es file
2. Gave permission to connect to the Xserver from localhost: xhost +
localhost
3. started the Xserver with DISPLAY 0 as an ordinary user.
4. started JServ manually with DISPLAY 0, using the following script:
#!/bin/sh
properties=3D/usr/local/jserv/etc/jserv.properties
log=3D/usr/local/jserv/logs/jserv_manual.log
CLASSPATH=3D$CLASSPATH:/usr/local/JSDK2.0/lib/jsdk.jar
CLASSPATH=3D$CLASSPATH:/usr/local/jserv/libexec/ApacheJServ.jar
java org.apache.jserv.JServ $properties $1 2>> $log
Thank you very much for your help. I will add your answers to the faq as=
it
might save someone some time.
=C1sta
----- Original Message -----
From: Richard Hallier <in...@fivia.com>
To: Java Apache Users <java-apa...@list.working-dogs.com>
Sent: Monday, January 24, 2000 6:48 PM
Subject: RE: Problems with images in servlets (classes not found)
Jon Skeet <sk...@pobox.com> a écrit dans le message :
MPG.142a8f7e69ace51298a682@news...
> lpe...@connectsuite.com wrote:
> > Hello,
> > This servlet can display an image if it run under MS NT server. But it
does
> > not work under GNU/Linux RedHat 6.0 server.
> > Does anybody knows about this problem ?
> > Is it possible to a servlet to read a jpeg image into a frame, modify
it,
> > and then return an encoded jpg stream as response with Linux.
>
Jon Skeet
> Thanks to your answer Jon,
> And sorry : This problem was solved by Richard Hallier in January (see
> after)
> It works fine ! Thanks to Richard too ;-)
> However, I can't understand why there is no reaction by Sun : A servlet
> running better with Microsoft than Linux ! My god !
There are plenty of reactions from Sun, one of which is "headless Java"
for 1.4, where you don't need an X server to do such things...
Lionel Peron
I've spent a lot of time to fix the problem and we are waiting for Merlin
(1.4) with attention ...
Another way is http://www.eteks.com/pja/en/
Why not...
Jon Skeet <sk...@pobox.com> a écrit dans le message :
MPG.142af5e7fd99dab198a684@news...
Jon Skeet
> I was talking about the lack of communication from Sun (for me of course).
Well, I think having a nicely searchable bug file which gives a
workaround is a fair amount of communication...
Juergen Kreileder
Jon> lpe...@connectsuite.com wrote:
>> I was talking about the lack of communication from Sun (for me
>> of course).
Jon> Well, I think having a nicely searchable bug file which gives
Jon> a workaround is a fair amount of communication...
Also, searching the usenet archives should show numerous answers to
this question.
BTW, there is a second solution for problem: The 'Pure Java AWT
Toolkit' (http://www.eteks.com/pja/en/)
Juergen
--
Juergen Kreileder, Blackdown Java-Linux Team
http://www.blackdown.org/java-linux.html
JVM'01: http://www.usenix.org/events/jvm01/
Lionel Peron
Have you ever be irritated.
I'm using JDK 1.2.2. I try 1.3 beta. I'm waiting now 1.4 ... and hope
Jon Skeet <sk...@pobox.com> a écrit dans le message :
MPG.142c0ae72948cf4c98a696@news...
> lpe...@connectsuite.com wrote:
> > I was talking about the lack of communication from Sun (for me of
course).
>
> Well, I think having a nicely searchable bug file which gives a
> workaround is a fair amount of communication...
>
Jon Skeet
> I agree, but from whom?
Well, Sun hosts it and have replied to it. Given that all the information
is there on their site, it would seem silly to require them to do *more*
to communicate about it, wouldn't it?
I agree it's an irritating problem though.