Working with shared libraries in Java JNA

29 Sep 2023

Shared libraries, also known as dynamic-link libraries (DLL) in Windows or shared objects (SO) in Unix-like systems, are an essential component of many software applications. They provide reusable code and resources that can be used by multiple programs simultaneously.

In Java, working with shared libraries can be achieved using the Java Native Access (JNA) library. JNA provides a simple and convenient way to load and interact with shared libraries from Java applications.

Step 1: Add JNA Dependency

The first step is to add the JNA dependency to your Java project. You can do this by including the following Maven dependency in your pom.xml file:

<dependencies>
    <dependency>
        <groupId>net.java.dev.jna</groupId>
        <artifactId>jna</artifactId>
        <version>5.9.0</version>
    </dependency>
</dependencies>

If you are not using Maven, you can manually download the JNA library from the JNA GitHub repository and include it in your project.

Step 2: Load the Shared Library

To load a shared library using JNA, you need to define an interface that extends the Library interface provided by JNA. The interface should declare the methods that you want to call from the shared library.

Here’s an example:

import com.sun.jna.Library;
import com.sun.jna.Native;

public interface MyLibrary extends Library {
    MyLibrary INSTANCE = Native.load("mylibrary", MyLibrary.class);
    
    void myFunction();
}

In this example, we define an interface called MyLibrary that extends the Library interface. We use the Native.load method to load the shared library named “mylibrary” and bind it to an instance of the MyLibrary interface.

Step 3: Call Functions from the Shared Library

Once the shared library is loaded, you can call its functions through the interface defined in the previous step.

public class Main {
    public static void main(String[] args) {
        MyLibrary.INSTANCE.myFunction();
    }
}

In this example, we call the myFunction method from the loaded shared library.

Conclusion

Working with shared libraries in Java with the help of JNA provides a convenient way to leverage existing libraries and functionalities. By following the steps outlined in this article, you can seamlessly integrate shared libraries into your Java applications. Make sure to check out the official JNA documentation for more advanced usage and additional features.

#Java #JNA