Manifest and classpath frustration

Question

I have a very simple standalone application. It is not an applet - it's a simple command line program that parses an XML stream and stores the results in a database. This app depends on a ton of external jar files. I would like to be able to build and run this thing - on different platforms - without having to mess with a bat or sh script. From perusing the web, it seems like I should be able to do this with a custom manifest file ... but I can't seem to get it to work. I keep getting a class not found error. In a nutshell, my jar looks like this
lib
com
META-INF
Insid the lib directory are around a dozen jar files
Inside the com directory are all my class files
Inside META-INF is the manifest file.
My manifest file looks like this:
Main-Class: com.mainClass.RunMe
Class-Path: lib/jarOne.jar
**lib/jarTwo.jar
**lib/jarThree.jar
Note that the *'s indicate spaces and I do have a blank line at the end of file.
When I try to execute using:
java -jar myJar.jar
I continually get class not found errors. If I run in verbose mode, I can see that my classes aren't getting loaded.
Can I do what I'm trying to do? Any pointers would be greatly appreciated as I'm running out of ideas and patience.
THanks

Answer 1

This isn't always legal. You can't "legally" assume you can extract any commercial jar file and bundle it with your app. If everything is open-source then there should be no problem. But for commercial apps, this wont work, at least legally.
There are two solutions that work best. One is to use an installer that provides an executable launcher (.exe on windows, .sit on mac, etc). This will provide a setup.exe (or setup.sit or setup.sh or something for each platform), that will then install your app like a commercial application. This will take care of unzipping everything you want in the right directories. There are a couple of free/open-source installers, VAInstall is one that I can think of that aren't too shabby. At work we use Install4J which is pretty good.
The other way is to use a custom classloader. First, your initial "main" class is nothing but a stub loader. It simply creates an instance of this URLClassloader subclass. You use it to find and run your "real" main() method within the classpath. URLClassLoader has a protected addURL(), but the constructor allows you to pass an array of URL objects, each that can be a directory of .class files or specific .jar/.zip files that become the classpath for the classloader instance. With this info, you can use a custom loader to add each of your .jar files located on disk as part of the classpath. The problem is, if they are on-disk, this isn't helping. What your custom loader needs to do is override loadClass(), getResource() and so forth, and provide a way to find classes from embeded jar/zip libraries inside the main jar file. This way, each time any class uses a class in an embeded jar/zip, your custom classloader looks inside the embeded jar/zip files for it as well. It's not prettty, but it works well.
One final thought, a plugin engine based application framework is a way to go. My own project, www.platonos.org (sorry, as of this posting the site is not up yet, but the project at sourceforge is available and CVS contains the code) can solve these issues. In our plugin engine, which is about 70K, each plugin has it's own classloader and classpath, and our PluginClassLoader not only handles embeded jar/zip files, but resources as well within them. Also, a plugin first searches its classpath before going to the parent to find classes, with the exception of java classes which are delegated to the bootstrap loader which is what loads rt.jar.