How can java directly access DLL

Question

I have some DLLs that are either written in C or C++ ( no access to source code), I now need to access some objects from it. is there a quick way to do this? are there any libraries already developed to allow my java code to access the objects inside those DLLs directly?
This is to convert some powerbuild code to java and the powerbuilder code is like this":
OLEObject loo_test ;
loo_test.connectToNewObject("AMS5.Almi);
then it just uses loo_test to call the methods and get results
AMS5 is the application name (there is actually an ams5.exe in the directly), and then a whole bunch of DLLs. I do not know which DLL is the code actually using..
any help will be greatly appreciated!

Answer 1

Clearly, at minimum, you need to know which DLLs contain the methods you're interested in. If you look at the JNA example below, it loads a Windows system DLL then contains 'beep', describes how to call it, then calls it. You will need to do something similar:
* JNATest.java
* Created on 24 August 2007, 12:12
package com.sdl;
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Structure;
import com.sun.jna.ptr.LongByReference;
import com.sun.jna.win32.StdCallLibrary;
/** @author amalcolm */
public class JNATest
    // Windows XP kernel library
    interface Kernel32 extends StdCallLibrary
        void Beep(int frequency, int duration);          
    public static void main(String[] args)
           Kernel32 kernel32=(Kernel32)Native.loadLibrary("kernel32",Kernel32.class);
            for(int freq=10;freq<10000;freq*=2)
                kernel32.Beep(freq, 5);
}