Java use library . DLL

Question

I’m having trouble creating the java interface, because I can’t understand the header of the function in C.

Example Header function C:

CMOEP_API char * CALLCONV CMP_GetLastError( );

Now in java I have like this but I don’t know how to implement the methods:

public class DllFIles {


    public static void main(String[] args) {
     CMOEP lib = new CMOEP();
        System.out.println("ERRO: " +lib.CMP_GetLastError());

    }

}
class CMOEP{
    static {
        System.loadLibrary("CMOEP");
    }
    public native char[] CMP_GetLastError( );
    //    CMOEP_API char * CALLCONV CMP_GetLastError( );

    public CMOEP(){}
}

Any ideas/help?

Answer 1

You can use this Github project to make your life easier: https://github.com/twall/jna

Step by step:

1. Create a Maven Project
2. Create the source C
3. Create the Java interface
4. Create the Java class

Sources:

dependency on pom.xml

    <dependency>
        <groupId>net.java.dev.jna</groupId>
        <artifactId>jna</artifactId>
        <version>4.1.0</version>
    </dependency>

Code C

#include <stdio.h>

int soma(int num1, int num2){
  int resultado = num1 + num2;
  return resultado;
}

Java interface

package jna;

import com.sun.jna.Library;

public interface SomaJNA extends Library {
  public int soma(int num1, int num2);
}

Java class

package jna;

import com.sun.jna.Native;

public class FazSoma {
    public static void main(String[] args) {
        SomaJNA calculadora = (SomaJNA) Native.loadLibrary("somadorJNA",
                SomaJNA.class);

        int num1 = Integer.parseInt(args[0]);
        int num2 = Integer.parseInt(args[1]);

        int resultado = calculadora.soma(num1, num2);
        System.out.println("A soma é: " + resultado);
    }
}

As in Project Eclipse

That’s All !