Re: Linking .jar.so

[Benjamin de Dardel <benjamin dot dedardel at gmail dot com>]

Hi David,

Thanks for your response : I can compile my tests now.
But I have some errors in the execution.
I don't know what is missing ?

>> the first one, without -findirect-dispatch option :
- cpp
org::apache::tools::ant::Main * pMain = new org::apache::tools::ant::Main();

$ gcj -shared -fjni -fPIC -Wl,-Bsymbolic /opt/ant/lib/ant-launcher.jar 
-o ant-launcher.jar.so
$ gcj -shared --classpath=/opt/ant/lib/ant-launcher.jar -fjni -fPIC 
-Wl,-Bsymbolic /opt/ant/lib/ant.jar -o ant.jar.so
...
$ ./test.bin
Unhandled Java exception:
java.lang.NoClassDefFoundError: org.apache.tools.ant.Main
  at java.lang.Class.initializeClass(natClass.cc:727)
Caused by: java.lang.NullPointerException
  at java.lang.Class.initializeClass(natClass.cc:717)

>> the second one, by instrospection :
- cpp
String *className = JvNewStringLatin1("org.apache.tools.ant.Main");
Class::forName( className );

$ gcj -shared -findirect-dispatch -fjni -fPIC -Wl,-Bsymbolic 
/opt/ant/lib/ant.jar -o ant.jar.so
$ gcj -shared -findirect-dispatch -fjni -fPIC -Wl,-Bsymbolic 
/opt/ant/lib/ant-launcher.jar -o ant-launcher.jar.so
...
$ ./test.bin
Hello from C++
Unhandled Java exception:
java.lang.ClassNotFoundException: org::apache::tools::ant::Main
  at java.lang.Class.forName(natClass.cc:101)
  at java.lang.Class.forName(natClass.cc:125)

David Daney a écrit :
> Benjamin de Dardel wrote:
> > Hi all,
> >
> > I'm trying to convert .jar to .so and then linking it with a .cpp 
> > program.
> > Here are the steps I did.  I fail to link .o and .so ! May be you 
> > have an idea to solve this problem ?
> >
> > Thanks,
> > Benjamin
> >
> >  >> ERROR
> > $ gcj -o essai3.bin essai3.o -L . -lgcj -lstdc++ ant.jar.so 
> > ant-launcher.jar.so
> > test.o: In function `main':
> > test.cpp:22: undefined reference to `void 
> > org::apache::tools::ant::Main::main(JArray<java::lang::String*>*)'
> > collect2: ld returned 1 exit status
> >
> >  >> STEPS
> > $ gcj -shared -findirect-dispatch -fjni -fPIC -Wl,-Bsymbolic 
> > /opt/ant/lib/ant.jar -o ant.jar.so
> > $ gcj -shared -findirect-dispatch -fjni -fPIC -Wl,-Bsymbolic 
> > /opt/ant/lib/ant-launcher.jar -o ant-launcher.jar.so
> > $ gcjh -v -cni -classpath 
> > /opt/ant/lib/ant.jar:/opt/ant/lib/ant-launcher.jar:/usr/lib/jvm/java-6-sun/jre/lib/rt.jar 
> > org.apache.tools.ant.Main
> > $ g++ -c -g -O -I. test.cpp
> > $ gcj -o essai3.bin essai3.o -L . -lgcj -lstdc++ ant.jar.so 
> > ant-launcher.jar.so
> >
> >  >> Program : test.cpp
> > #include <gcj/cni.h>
> > #include <java/lang/System.h>
> > #include <java/io/PrintStream.h>
> > #include <java/lang/Throwable.h>
> >
> > #include <org/apache/tools/ant/Main.h>
> >
> > int main(int argc, char *argv[])
> > {
> >    using namespace java::lang;
> >
> >    try
> >    {
> >         JvCreateJavaVM(NULL);
> >         JvAttachCurrentThread(NULL, NULL);
> >
> >         String *message = JvNewStringLatin1("Hello from C++");
> >         JvInitClass(&System::class$);
> >         System::out->println(message);
> >              org::apache::tools::ant::Main::main(NULL);
> >        
>
> You cannot use  -findirect-dispatch with CNI like this.
>
> You might be able to use reflection to invoke main, or don't compile 
> the main class with -findirect-dispatch.
>
>
> >         JvDetachCurrentThread();
> >    }
> >    catch (Throwable *t)
> >    {
> >         System::err->println(JvNewStringLatin1("Unhandled Java 
> > exception:"));
> >         t->printStackTrace();
> >    }
> > }