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How can I creating executable JAR with SWT that runs on all platforms?

Answer 1

A:

Maybe http://one-jar.sourceforge.net/ (Maven plugin at http://code.google.com/p/onejar-maven-plugin/) could help in that direction...

Marcel 2010-01-10 14:35:09

Answer 2

+1 A:

IIUC, you'd still have the problem of specifying the platform-specific JNI library. You might be able to leverage Java Web Start for this, but I haven't tried. Alternatively, some projects build custom installers for supported platforms. For example, Deploying SWT Applications on Mac OS X describes how to construct an SWT Mac application bundle. The approach is used in this example. I've also seen this JarBundler Ant Task used.

Addendum: the article Deploying an SWT application on Java Webstart includes some useful references.

trashgod 2010-01-10 16:40:04

I have now tried with an URLClassLoader but there are two problems: If the JAR isn't in the ClassPath in the MANIFEST.MF, then loading the DLLs will fail. This means I have to add *all* SWT JARs to the classpath at the same time. This leads to the problem that the 32bit and 64bit DLLs are visible and loading of either will fail. *sigh* In the end, I'll add all JARs to the class path but copy only a single SWT JAR into the lib directory. This way, only a single JAR will load.

Aaron Digulla 2010-01-10 22:22:17

I can see the technical appeal, but I can also see the maintenance difficulties. Facing a similar problem, I added a link to a SO article mentioning JWS.

trashgod 2010-01-10 23:18:52

Answer 3

A:

It will be easier to use different shell scripts for different platforms and specify platform-specific jar in the script.

tulskiy 2010-01-10 20:12:55

I could write shell scripts but I was really hoping to avoid that. My current solution (add all SWT JARs to the classpath but copy only the correct one into the lib directory) works. Now, I only need to write an installer :)

Aaron Digulla 2010-01-10 22:23:23

Answer 4

+4 A:

For my current job I needed to supply an executable jar that could load jars inside itself and execute a second main(). Basically a bootstrap main() and an application main().

Step 1. in the manifest "main-class" you put your bootstrap class

Step 2. When your bootstrap class runs it unjar's its own jar and all jars inside it to a temp directory. Use something like the line below to get your own jar.

Main.class.getProtectionDomain().getCodeSource().getLocation().toURI()

Step 3. Your bootstrap class detects the OS via the "os.name" property and loads the appropriate jars from the temp directory with this

private static void loadJarIntoClassloader( URL u ) throws Exception
{
    URLClassLoader sysLoader = (URLClassLoader) ClassLoader.getSystemClassLoader();

    Class<URLClassLoader> sysclass = URLClassLoader.class;
    Method method = sysclass.getDeclaredMethod("addURL", URL.class);
    method.setAccessible(true);
    method.invoke(sysLoader, new Object[]{u});
}

Step 4. Now you should be able to run your application by calling the application main().

NOTE: This little hack depends on your JVM using URLClassLoader as its SystemClassLoader, which is true for Sun JVMs, not for sure on others.

This way you can deliver a single jar only, and it will unpack itself and run with the correct jars.

karoberts 2010-01-11 05:00:00

If you want to be independent of the type of the classloader, just use the factory `newInstance(urls, parentClassLoader)` method to wrap it and then install the new classloader with `Thread.currentThread().setContextClassLoader ()`.

Aaron Digulla 2010-01-11 08:19:20

+1 Interesting idea to create the classpath in one main and then call another.

Aaron Digulla 2010-01-11 08:20:20

@Aaron thanks for the tip, I'll have to try that

karoberts 2010-01-11 18:23:12

Answer 5

+1 A:

Look at this, there is a code sample: Create cross platform java swt application

Matías 2010-07-23 13:30:37

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How can I creating executable JAR with SWT that runs on all platforms?

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