Problem: codebase, jar and image reloading problem please help!

Question

Hi Java Gurus,
I have written an applet that extends JApplet for viewing webcam. In order to reduce the download time I put my classes into a doorcam.jar file. The following is my <applet> tag in my html file.
<applet code="CameraApplet.class"
archive="doorcam.jar"
     codebase = "webcam/classes"
     width="375" height="475">
<param name="imagePath" value="http://judge/webcam/images">
<param name="webCamImage" value="door.jpg">
<param name="COMPort" value="COM2">
<param name="frameRate" value="10"> <!-- could not exceed more than 10-->
<param name="host" value="judge">
</applet>
The fist problem is that my class file does not get loaded from the jar file if i provide the "codebase" attribute as above. Instead the browser load every single class file from the webserver. This has some problem too. Coz the browser sometimes just thorough NullPointerException or ClassNotFoundException. After much of debugging I found out that the problem is the IE browser which seldom fails to load classes or image file from the server. If i referesh the browser the applet and all its classes loaded successfully and runs smoothly. This behaviour never occurs when running with "appletviewer".
I wanted all my classes to be loaded from my jar file. After much of trial and error I found out that if i remove "codebase" attribute the browser loads the classes from my jar file and applet loads very fast. This is where the second problem comes in. The browser does not reload my webcam image file so that the webcam become alive with live images, like before.
If I run on "appletviewer" everything works fine my web cam is displayed properly. But in IE browser the image does not get reloaded when I refresh my image to give live to my webcam display. The refresh method is given below.
private void refresh(final URL url) {
Image webCamImage =getImage(url);
webCamImage.flush(); // flush out the previous image
webCamImage = getImage(url); // get a new image
webCamImageIcon.setImage(webCamImage); webCamImageIcon.paintIcon(webCamLabel, webCamLabel.getGraphics(), 15, 15);
When I add the "codebase" attribute back, the image gets reloaded for every refresh() and everything works fine. But the classes are also loaded from the server. And occasionally also suffers Class loading and image loading problem. As I presented earlier, when I do refreshing in the browser everything gets loaded and the applet function correctly with web cam displaying very well.
The problem is so strange that I could not find any way to solve it.
It would be a great help to me if somebody provide me some work around to the problem.
I tested on Windows 2000, Windows XP, IE 5.5, IE 6 with J2SDK 1.4.0.
Thank you all very much in advance.
best regards,
Judge

Answer 1

Thank you so much for the suggestions. I did tried the way u suggested. The problem still the same.
I think its the problem between IE browser and Java Plug-in.
I which SUN would find these incompatibilities and solve these problems.
I even tried using java SDK and plug-in 1.4.1 it even worst. It can't even load an applet. And it does not show any loading messages nor any error messages. It just show a cross sign on the upper left coner.
I would be so glad, if Sun would try to eliminate the inconsistancies such as caching, loading, initializing etc between browser and its Java plug-In. For example, applets behave well in appletviewer and behave unpredictably in browser environment.
I have seen so many people in the forums with all sorts of problems because of this.
Right now I m desperately looking for work around to my problem.
If somebody would provide me with the solution to my problem it would be a great help to me.
thank you all so much.
best regards,
Judge