如何生成64位.dll哪个gcc编译器或其他。无法在AMD 64位平台上加载IA 32位.dll

Question

Hi I didn't find solution how to create 64 bit dll. And use it's native c++ methods. I use Java code metodynatywne.java :

class metodynatywne {

static {
  System.loadLibrary("metodynatywne");
 }
native public void sayHello();

public static void main (String argv[])
{
    new metodynatywne().sayHello();
}  }

then generated metodynatywne.h using javah -jni metodynatywne

I wrote metodynatywne.cpp code :

   #include <jni.h>
   #include <iostream>
   #include "metodynatywne.h"
   using namespace std;

   JNIEXPORT void JNICALL
   Java_metodynatywne_sayHello(JNIEnv * env, jobject self)
      {
cout << "Hello World!" << endl;
   }

I ussed gcc to create my dll with comands :

 c:\>c++ -I c:\java7\include -I c:\java7\include\win32 -c metodynatywne.cpp

and

   c:\>c++ -shared metodynatywne.o -o metodynatywne.dll

and what what I'm getting is error message:

c:\>java metodynatywne
Exception in thread "main" java.lang.UnsatisfiedLinkError: C:\Programowanie\UJ\Semestr2\ZPG\PerfCount\cwiczenie\metodynatywne.dll: Can't lo
 ad IA 32-bit .dll on a AMD 64-bit platform
    at java.lang.ClassLoader$NativeLibrary.load(Native Method)
    at java.lang.ClassLoader.loadLibrary1(Unknown Source)
    at java.lang.ClassLoader.loadLibrary0(Unknown Source)
    at java.lang.ClassLoader.loadLibrary(Unknown Source)
    at java.lang.Runtime.loadLibrary0(Unknown Source)
    at java.lang.System.loadLibrary(Unknown Source)
    at metodynatywne.<clinit>(metodynatywne.java:4)

I used Java 1.4 32 bit javac compiler and java7 x64 compiler both metods gave me the same error. How can I deal with that? Use another c++ compiler if yes how force this compiler to create usable by my java dll file. I working on Windows 7 64 bit.

How I can make from cpp file a 64 bit dll (with gcc) ? Or other comand line compiler ?

Thanks a lot for any comments and help provided.

Answer 1

You should recompile the DLL for 64-bit (you must download 64-bit build tools). Also you can switch to 32-bit JVM (just download 32-bit JVM).

Answer 2

这个编译器标志应该有帮助：c ++ --64 -DARCH_X86_64 = 1 file.cpp

Answer 3

Still no accepted answer on this one, so I'll bite... As Denis mentioned, you'll need to download a 64-bit compiler for generating your .dll. These days most people use MinGW-w64 for this on Windows ( http://www.mingw.org or direct download here http://sourceforge.net/projects/mingw-w64/files/latest/download?source=files ) which has a pretty nice installation package. Caution - If you don't use the installation package you'll need to install the whole toolchain on your own. Then you would use this 64-bit compiler executable (something like 'x86_64-w64-mingw32-g++') instead of the 32-bit gcc to generate your library.

As you noted above, you do need to be careful about the version of java you are using to be sure it matches the architecture of the C++ library you have compiled. This means both the Javah auto-generation of your JNI header and the Java runtime that you call it from.