Access to DLLs with JNI??

Question

Hi All,
I�ve just created a DLL in VC++ version 6
I�m using simulation packages to access functions within this DLL, this runs just fine.
My question is: -
How can I get my java application to access the DLL functions as well?
If I use JNI my simulation models don�t recognise the functions anymore.
Is there any other way of accessing my DLLs without using JNI?
Any solution would be much appreciated.
John.

Answer 1

No luck this time either:
Here is the code that I'm using
(1)
//hello.java
class HelloWorld
public native long displayHelloWorld();
static
System.loadLibrary("control_unit");
public static void main(String[] args)
long temp = 0;
temp = new HelloWorld().displayHelloWorld();
System.out.println("The returned value is "+temp);
(2)
// HelloWorldImp.c
#include "stdafx.h"
#include<stdlib.h>
#include<stdio.h>
#include<iostream.h>
#include "jni.h"
#include "HelloWorld.h"
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved )
return TRUE;
DWORD WINAPI returnValue()
return 8;
JNIEXPORT jlong JNICALL
Java_HelloWorld_returnValue(JNIEnv *env, jobject obj)
return (jlong)returnValue();
(3)
//Generated File
/* DO NOT EDIT THIS FILE - it is machine generated */
#include "jni.h"
/* Header for class HelloWorld */
#ifndef IncludedHelloWorld
#define IncludedHelloWorld
#ifdef __cplusplus
extern "C" {
#endif
* Class: HelloWorld
* Method: displayHelloWorld
* Signature: ()J
JNIEXPORT jlong JNICALL Java_HelloWorld_displayHelloWorld
(JNIEnv *, jobject);
#ifdef __cplusplus
#endif
#endif
(4)
//Commands used
javac hello.java
javah HelloWorld
cl -Ic:\jdk1.2.2\include -Ic:\jdk1.2.2\include\win32 -LD HelloWorldImp.c -Fecontrol_unit.dll
However I usually build the dll in VC++ ver 6 as this allows my dlls to work with my sim models
I only use the CL to get the JNI working
And when I try to run the java application I get the following: -
Exception in thread "main" java.lang.UnsatisfiedLinkError: displayHelloWorld
at HelloWorld.main(hello.java:13)
Which is "temp = new HelloWorld().displayHelloWorld();" in hello.java
Any reason as to why it's not working?
If you have any questions please let me know and I'll get back to you.
Am I building the dll in the wrong manner?
Thanks again,
John.