Well the framework and API I am using are very large, so much so that it
would be unreasonable to rewrite them in Java. Sorry for the somewhat
unspecific question? Really I wanted to know why the class loader couldn't
find the jess.Rete class, when I have jess.jar on my classpath, and have it
in the directory where the c++ program executes.
Here is the c++ code where I create the JVM:
*#include <jni.h>*
*#include <cstdlib>*
*using namespace std;*
*int main() *
*{*
* JNIEnv *env;*
* JavaVM *jvm;*
* jint res;*
* jclass cls;*
* jmethodID mid;*
* jstring jstr;*
* jclass stringClass;*
* jobjectArray args;*
* *
* JavaVMInitArgs vm_args; /* JDK/JRE 6 VM initialization arguments */*
* JavaVMOption* options = new JavaVMOption[1];*
* options[0].optionString = (char*)&"-Djava.class.path=."; //the
current directory is where jess.jar is also*
* vm_args.version = JNI_VERSION_1_6;*
* vm_args.nOptions = 1;*
* vm_args.options = options;*
* vm_args.ignoreUnrecognized = false;*
*
*
* /* load and initialize a Java VM, return a JNI interface*
* * pointer in env */*
* JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);*
* cls = env->FindClass("TestJNIJessInvoke");*
* mid = env->GetStaticMethodID(cls, "main", **
"([Ljava/lang/String;)V");*
* jstr = env->NewStringUTF("");*
* stringClass = env->FindClass("java/lang/String");*
* args = env->NewObjectArray(1, stringClass, jstr);*
*
*
* env->CallStaticVoidMethod(cls, mid, args);*
* *
* if (env->ExceptionOccurred()) *
* {*
* env->ExceptionDescribe();*
* }*
* jvm->DestroyJavaVM();*
*}*
On Tue, Sep 27, 2011 at 11:58 AM, Dusan Sormaz <[email protected]> wrote:
> Hunter,
>
> This is not Jess specific question. JVM simply can not find Java class to
> load.
> Can you show snippet of the C++ code that starts jvm and tries to load
> TestJNIJessinvoke?
>
> As for overall design, is C++ requirement? Can you do it all in Java?
>
> Dusan Sormaz
>
>
> On 9/26/2011 8:51 PM, Hunter McMillen wrote:
>
> Hello everyone,
>
> I am working on a project where I am using a C++ framework and API to
> create a game agent. My agent has to be flexible so it can react to/predict
> events that occur inside the game environment, Jess has the kind
> of flexibility that I need for my agent to be good, but I am having trouble
> connecting to Jess from C++ and that is where I was hoping someone could
> help me out.
>
> *What I am doing right now*
> I have a C++ program that starts a Java Virtual Machine and searches for a
> Java class file name "TestJNIJessInvoke"
>
> Inside of "TestJNIJessInvoke.java" I define a simple function in Jess,
> and try to call that function then print the result
> import jess.*;
> public class TestJNIJessInvoke
> {
> public static void main(String[] args) throws JessException
> {
> Rete r = new Rete();
> r.executeCommand("(deffunction square (?n) (return (* ?n ?n)))");
> Value v = r.executeCommand("(square 3)");
>
> System.out.println(v.intValue(r.getGlobalContext()));
> }
> }
>
> But when I try to compile and link the C++ file with:
> *cl *
> * -I"C:\Program Files\Java\jdk1.7.0\include" *
> * -I"C:\Program Files\Java\jdk1.7.0\include\win32" *
> * TestJNIJessInvoke.cpp *
> * -link "C:\Program Files\Java\jdk1.7.0\lib\jvm.lib"*
> *
> *
> I get a class loader exception:
> *Exception in thread "main" java.lang.NoClassDefFoundError: jess/Rete*
> * at TestJNIJessInvoke.main(TestJNIJessInvoke.java:6)*
> *Caused by: java.lang.ClassNotFoundException: jess.Rete*
> * at java.net.URLClassLoader$1.run(URLClassLoader.java:366)*
> * at java.net.URLClassLoader$1.run(URLClassLoader.java:355)*
> * at java.security.AccessController.doPrivileged(Native Method)*
> * at java.net.URLClassLoader.findClass(URLClassLoader.java:354)*
> * at java.lang.ClassLoader.loadClass(ClassLoader.java:423)*
> * at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)*
> * at java.lang.ClassLoader.loadClass(ClassLoader.java:356)*
> * ... 1 more*
> *
> *
> Exception in thread "main" java.lang.NoClassDefFoundError: jess/Rete
> at TestJNIJessInvoke.main(TestJNIJessInvoke.java:6)
> Caused by: java.lang.ClassNotFoundException: jess.Rete
> at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
> at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
> ... 1 more
>
> *Questions*
>
> 1) Is there some other directory that I am supposed to be including that
> has the .class files for Jess? Right now all I am including is jess.jar
> 2) Is the general design I have a good idea? or is there a better way to
> facilitate communication between Jess and C++?
>
>
>
> Thanks,
> Hunter McMillen
>
>
> --
> ***************************************************
> * Dusan Sormaz, PhD, Associate Professor
> * Ohio University
> * Department of Industrial and Systems Engineering
> * 284 Stocker Center, Athens, OH 45701-2979
> * phone: (740) 593-1545
> * fax: (740) 593-0778
> * e-mail: [email protected]
> * url: http://oak.cats.ohiou.edu/~sormaz/
> ***************************************************
>
>
