I’m attempting to use a JNI provided by somebody else (CLIPS).
Basically I
need to require a jar and then include a Java class into my JRuby
environment. When my folder is setup like this it all works:
script.rb
CLIPSJNI.jar
libCLIPSJNI.jnilib
[script.rb]
include Java
require ‘CLIPSJNI.jar’
include_class ‘CLIPSJNI.Environment’
puts Environment
% jruby script.rb
Java::CLIPSJNI::Environment
However when I setup like this I get an error:
script.rb
lib/
CLIPSJNI.jar
libCLIPSJNI.jnilib
% jruby script.rb
(eval):1:in `include_class’: cannot link Java class
CLIPSJNI.Environment,
probable missing dependency: no
CLIPSJNI in java.library.path (NameError)
I can fix it by setting java.library.path from the command line:
% jruby -J-Djava.library.path=lib clips.rb
Java::CLIPSJNI::Environment
So how can I set java.library.path within my script so I don’t need the
command line flag? I’ve tried:
current = java.lang.System.getProperty(“java.library.path”)
java.lang.System.setProperty(“java.library.path”,
“#{current}:#{File.expand_path(‘lib’)}”);
And:
java.lang.System.load(File.expand_path(‘lib/libCLIPSJNI.jnilib’));
No luck so far. Any ideas? Thanks.
On Wed, 04 Nov 2009 18:43:21 +0200, Simon C.
[email protected] wrote:
So how can I set java.library.path within my script so I don’t need the
command line flag?
I don’t think you can. Like many other system properties (e.g.
java.class.path), the jvm copies the value at startup and ignores any
changes thereafter. There’s nothing jruby can do about it.
No luck so far. Any ideas? Thanks.
These things come to mind:
Add the folder containing the native library to PATH (if on windows)
or
to LD_LIBRARY_PATH (e.g. linux, solaris) before launching your script.
Make a short shell script to launch your script.
As a variation of this, you could make your ruby script spawn a copy
of
itself in a new process if it notices java.library.path does not contain
the folder you want (setting java.library.path correctly for the new
process, naturally). Note that there are some subtleties about launching
a
new jruby process from jruby (IIRC there’s an optimization that prevents
a
new process from being created and instead runs the script in the same
process) - others more knowledgeable can comment more on this.
::Antti::
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