Using JNA to access export native classes

[sattu]

Hi everyone,

Currently I am working on java project which uses methods and classes present inside a DLL. Suppose I have such a method inside the DLL(named MyDLL.dll):

Method inside my DLL code
extern "C" __declspec(dllexport) int myMethod();

corresponding JNA implementation
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Platform;

/** Simple example of native library declaration and usage. */
public class HelloWorld {
public interface CLibrary extends Library {
CLibrary INSTANCE = (CLibrary) Native.loadLibrary("MyDLL", CLibrary.class);
int myMethod();
}

public static void main(String[] args) {
String libPath = "path to MyDLL.dll";
System.setProperty("jna.library.path", libPath);
int RetVar = CLibrary.INSTANCE.myMethod();
} ////main function ends

} ////class ends

So, my doubt is that like the function present inside the DLL, I have also got a class inside the DLL which needs to be exported:

Class inside my DLL code
extern "C" __declspec(dllexport) Class myClass
{
//////code inside class
};

So, now the question is how I am gonna use this native class inside my java code like i did for the native method?

[sattu]

Or I have an alternative doubt to it:

if the method inside my DLL is declared as follows:
extern "C" __declspec(dllexport) int myMethod();

that means i just need to declare a native equivalent of 'myMethod' to use it in my java code like:

public native int myMethod();

Now i can call the function as follows: int var = myMethod();

//********************Now the NEW part***********************\\

Inside the DLL, now I also have a class along with the method as follows:

class MyClass
{
public:
int var;
};

extern "C" __declspec(dllexport) MyClass __cdecl myMethod()
{
MyClass obj;
obj.var = 45;
return obj;
}
///////////////////////////DLL code ends\\\\\\\\\\\\\\\\\\\\\\\\

I hope you all noticed that now my return type is an object of a class rather than a normal int.

So, now the bigger question is, how I am going to use this native function (myMethod) inside my JAVA code? Previously the return type was just an integer, so it was easy. But now what or rather how?


See, I have mentioned my 2 doubts. So, clarification of either of the doubt will do.

It's very urgent. So, i would really be grateful if someone can provide me with any kind of solutions or helpful links?


Thanks in advance,

With regards,
Satya Prakash.