JNA to call a DLL without source code from java

Question

I have to call a dll method and I don't have the source code from dll, I was reading about JNI and understood that you should have the source to input the JNI library in the code (.h).

My second shoot is JNA, but I am getting the same error, although you don't have to change anything in DLL.

I created two classes to test:

interface:

package icom;

import com.sun.jna.Library;

public interface IConectorT extends Library {
    int StartConector(byte[] conectorStatus, String icomPath);
}

DLL method call:

package icom;

import com.sun.jna.Native;

public class ConectorTJna {

    public static void main(String args[]) {

        IConectorT lib = (IConectorT) Native.loadLibrary("ConectorT", IConectorT.class);
        int teste = lib.StartConector(null, "C:\\ICOM");
        System.out.println("RESULT: " + teste);
    }
}

When I call the lib.StartConector method I get this:

Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'StartConector': The specified procedure could not be found. at com.sun.jna.Function.(Function.java:179) at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:350) at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:330) at com.sun.jna.Library$Handler.invoke(Library.java:203) at $Proxy0.StartConector(Unknown Source) at icom.ConectorTJna.main(ConectorTJna.java:10)

Is the DLL using the C-style function names or C++-style mangled function names? Worst still if it is a .NET DLL. Verify this using Microsoft Depends.exe tool. If it is C++-style, then you need to create a C-style wrapper DLL for it before you can use it with JNA. For more info, refer this ochafik.com/blog/?p=131 and en.wikipedia.org/wiki/Name_mangling — ee.
– ee., Commented Aug 14, 2012 at 1:08
Do you have at least a slight idea what functions are exported by the DLL? You can use MS dumpbin /exports to find out the names of functions, hence knowing what package name of the Java stub is expected. But you won't know the full signatures, i.e. what parameters and their types is expected. Nobody will tell you that. You seem to have a little clue, given that you are already attempting to call some StartConector with some params. — Pavel Zdenek
– Pavel Zdenek, Commented Aug 14, 2012 at 8:53

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

Did you specify path to the library, e.g. using system property?

Here are the details from "Getting Started with JNA" guide:

Make your target library available to your Java program. There are two ways to do this:

The preferred method is to set the jna.library.path system property to the path to your target library. This property is similar to java.library.path, but only applies to libraries loaded by JNA.

Change the appropriate library access environment variable before launching the VM. This is PATH on Windows, LD_LIBRARY_PATH on Linux, and DYLD_LIBRARY_PATH on OSX.

Taken from: https://github.com/twall/jna/blob/master/www/GettingStarted.md

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Aug 13, 2012 at 21:29

Michał Majcherski

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1 Comment

user207421 Over a year ago

The error occurs looking up the function, not loading the library.

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