JNI: experience in creating DLLs with G++ (mingw32)?

Question

Hello.
I'm trying to create a DLL:
--------------/HelloWorld.cpp/------
#include <jni.h>
#include "HelloWorld.h"
#include <stdio.h>
JNIEXPORT void JNICALL
Java_HelloWorld_displayMessage(JNIEnv *env, jobject obj)
printf("Hello world!\n");
return;
I previously created 'HelloWorld.java'
class HelloWorld
public native void displayMessage();
static
System.loadLibrary("HelloWorldImp");
I created 'HelloWorld.class'.
I created the header file 'HelloWorld.h':
c:> javah -jni HelloWorld
But I do not have any idea to create the DLL.
I tried with:
c:> g++ -I"D:\j2sdk\include" -I"D:\j2sdk\include\win32" HelloWorld.cpp -shared -o HelloWorldImp.dll
But I get this error message when calling from 'Main.java':
Exception in thread "main" java.lang.UnsatisfiedLinkError: displayMessage
at HelloWorld.displayMessage(Native Method)
at Main.main(Main.java:6)
In order to get this message I created 'Main.java':
class Main
public static void main(String[] args)
HelloWorld hello = new HelloWorld();
hello.displayMessage();
Does anybody have any experience in creating DLLs with G++???
Thank you very much.

Answer 1

Or is it better GCC?