A possible way is to just unpack everything in the same folder, then to repack the whole with the jar tool.

What's the jar tool.. is this part of Processing or the Java component.  Could you provide a link or some instruction?  Thanks

This is what my directory looks like now...
Program.exe
jogl dlls
lib folder
-> library jar files and app jar
data folder
-> images folder
---> images
-> bin folder
---> shaders & textures
-> layout folder
---> exe called in program

jar.exe (or equivalent for others systems) is a command line tool available in the JDK.
Alternatively, you can create a simple .zip file and rename it.
But you need a manifest file in it.

I just found a tool, untested, that might help: http://www.ibm.com/developerworks/java/library/j-onejar/

Not sure if my idea is as simple as it seems...
BTW, you can keep several jar files, you just declare them in the JNLP file.

I have a related question.

I have a sketch that contains about 15 2.5 mb hi resolution images.  It takes a long time for the images to download before the app starts running.

Is is possible to package a sketch so that it can start playing before it has downloaded all the jar files?  The Sketch takes a long time to play through so I can easily write it so that it doesn't try to load most of the images until five minutes after the sketch has started playing through the first couple of images.

I'm looking at the onejar app - that looks interesting.  What I'm working on now is perhaps what I should have done a while ago.  I ran into problems loading certain files from the data directory when exporting, so now I'm trying to fix that so the entire data file can be embedded in the jar. 

Some lessons learned for embedding data into the jar during export.
Don't use "File" - it doesn't work for accessing files inside the jar.  Use loadBytes, loadStrings or createInput.  Don't use dataPath() inside loadBytes, loadStrings, or createInput - it is already defaulted to the Data folder and will break access to the jar.

Example

Bad:

1. File f = new File(dataPath("images" + File.separator + "ring.png"))
2. TextureData textureData = TextureIO.newTextureData(f, true, null);

Good:

1. TextureData textureData = TextureIO.newTextureData(createInput("images/ring.png"), true, "png");

Note: Updated based on the File.separator discovery listed below.

I think I'm stuck on the native libraries that are exported with OpenGL, as I can get it to work fine in P2D and P3D.  Does anyone have an example or instructions on how to bundle the windows dlls for JNLP deployment?

This is what I tried to do...

JNLP looks like this...

1. <?xml version="1.0" encoding="UTF-8"?>
2. <jnlp spec="1.0+" codebase="http://172.16.216.128/jnlp/randomlines/" href="test.jnlp">
3.     <information>
4.         <title>Processing Test</title>
5.         <vendor>guru</vendor>
6.         <icon href="Icon64.png" width="64" height="64"/>
7.         <icon kind="shortcut" href="Icon16.png" width="16" height="16"/>
8.         <icon kind="shortcut" href="Icon32.png" width="32" height="32"/>
9.         <icon kind="shortcut" href="Icon64.png" width="64" height="64"/>
10.         <icon href="Splash.png" kind="splash" />
11.         <desktop/>
12.         <offline-allowed/>
13.         <shortcut online="false">
14.               <desktop/>
15.         </shortcut>
16.     </information>
17.     <resources>
18.         <j2se version="1.5+" href="http://java.sun.com/products/autodl/j2se"/>
19.         <jar href="lib/randomlines.jar" main="true" />
20.         <jar href="lib/core.jar" main="true" />
21.         <jar href="lib/gluegen-rt.jar" main="true" />
22.         <jar href="lib/jogl.jar" main="true" />
23.         <jar href="lib/opengl.jar" main="true" />
24.         <jar href="lib/PeasyCam.jar" main="true" />
25.         <jar href="windows32.jar" main="false" />
26.     </resources>
27.     <application-desc
28.          name="ProcessinTestApp"
29.          main-class="randomlines"
30.          width="300"
31.          height="300">
32.      </application-desc>
33.      <update check="always" policy="prompt-update"/>
34. </jnlp>

Made some progress... this line
        <jar href="windows32.jar" main="false" />
should have been
        <nativelib href="windows32.jar" />
Added
    <security>
        <all-permissions/>
    </security>

Also, needed to sign ALL the jar files.

Folks.. I'm still completely stuck on this...

Progress...
The problem was File.separator.  I guess it doesn't like it as part of the string. 

Bad

1. byte[] ba = loadBytes("images" + File.separator + "icon.png");

Good

1. byte[] ba = loadBytes("images/icon.png");

Just wanted to say that I am reading this thread with interest and hope you'll keep adding to it when you find more problems and/or solutions.

Will do Andreas.. I do have more things to add and maybe it can all be turned into a wiki page.  Monday I'll add some info on creating and accessing separate jar files that hold additional files and where to put them in your Processing sketch.  Things that I've set to "lazy" download, containing images and sound files.  I'll also repost my latest JNLP.

Ok.. Some additional info learned.  So, if you want to package some of your images or sounds in a separate JAR file for lazy download or perhaps some other reason.  Here is what you do...
Example: Images Folder.  Zip the images folder (not just the contents, but the contents and the folder itself - zip the folder).  Rename .zip to .jar.

Should look like this:

images.jar
--> images
------> image1.png
------> image2.png

Place the images.jar in your "code" directory.

Then in your sketch, call it like this:

1. InputStream is = getJarStream("images/image1.png");

Couple Helpers

1. InputStream getJarStream(String file) {
2.   return getClass().getClassLoader().getResourceAsStream(file);
3. }
4. 
   
5. String getJarFile(String file) {
6.   URL ul;
7.   ul = getClass().getClassLoader().getResource(file);
8.   return ul.toString();
9. }

Passing a variable to your sketch from the JNLP file.  I found that this works pretty good.

JNLP FILE

1. <resources>
2. <property name="key" value="something"/>
3. </resources>

Processing

1. String prop = System.getProperty("key");
2. println(prop);