packaging native libraries

Danno Ferrin danno.ferrin at
Fri Apr 19 09:23:56 PDT 2013

My bad.  Looks like the code I was running at work has a fallback path for
when the loadLibrary fails.  Looks like it worked so seamlessly I had
assumed it was working.  That's the drawback of a good QA team I suppose.

On Fri, Apr 19, 2013 at 10:01 AM, Johan Vos <johan at> wrote:

> It doesn't work for me, on Windows, Linux or MacOs. Do you load the DLL
> using System.loadLibrary() rather than System.load()? I printed the value
> of java.library.path, and it was empty (as I would expect). In that case,
> System.loadLibrary() should always fail, I think.
> I checked how e.g. the Glass library is loaded in JavaFX, and
> does exactly what I would expect:
>  // Look for the library in the same directory as the jar file
>         // containing this class.
>         // If that fails, then try System.loadLibrary as a last resort.
> Loading the class from the jarfile is done using System.load(libFileName);
> There is a clever but dirty trick to circumvent the java.library.path
> issue, as pointed to me by Jose Pereda Llamas:
> That should work, but there is no guarantee this will work forever, as it
> relies on internal logic for "resetting" the java.library.path.
> - Johan
> 2013/4/19 Danno Ferrin <danno.ferrin at>
>> It worked for me last week.  I passed in the DLLs along with the jars as
>> a list of files, and the DLLs wound up in the /app dir for windows
>> alongside all the other jars, and the DLLs loaded just fine.
>> YYMV, I was doing this with my Gradle plugin, not the command line, or
>> ant, or  maven (I got 5 months to formalize this for my javaone talk).
>>  Also, I only did it with DLLs, not dynlibs or SOs.  I have no mac or linux
>> binaries to test it against anyway.
>> So basically, treat the library as a jar when packaging.
>> Also, I don't know about the javax.whatever namespace.  If we need a
>> rename I would be more in favor of something more like
>> .packager.  The javax namespace implies to me we
>> would want to use it in a typical runtime, not as a build time tool.  It
>> also implies more stability than native packaging processes will ever be
>> able to offer, what with each native platform coming up with new packaging
>> options at random intervals.  (First it's exe, then it's jar, or app, then
>> dmg, now it's mac store, oh wait, .debs are out of fashion, now they need
>> to be .mobapp... etc etc.)
>> On Fri, Apr 19, 2013 at 1:16 AM, Johan Vos <johan at> wrote:
>>> Hi,
>>> The javafxpackager is a great tool. I think it would actually make sense
>>> to
>>> move some of the code (from src/com/sun/javafx/tools/packager) to the
>>> javax. namespace and make it a public API, rather than having a single
>>> script.
>>> But I have an issue: I need to bundle an external Java library, that also
>>> comes with a native library. Bundling itself is not a problem with the
>>> javafxpackager, and loading the native library is also achievable, by
>>> unpacking the native lib, storing it in a temp file and loading it with
>>> System.load(String). However, if the library is also loaded using
>>> System.loadLibrary(String), the java.library.path is searched for the
>>> library.
>>> One solution is that external Java libraries should not attempt to load
>>> the
>>> native libraries themselves, rather rely on the developers to load the
>>> libraries. But since in most cases you don't control these external
>>> libraries, that will not work in all cases.
>>> However, with a growing tendency towards bundled native applications, I
>>> think the management of native dependencies is becoming more important.
>>> Ideas?
>>> - Johan
>> --
>> There is nothing that will hold me back.  I know who I am....
>> I remember wher I came from, and I feel stronger for knowing.
>>  Zane, Ninja of Ice.  Ninjago S01E07

There is nothing that will hold me back.  I know who I am....
I remember wher I came from, and I feel stronger for knowing.
Zane, Ninja of Ice.  Ninjago S01E07

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