Jna, Unload Dll from java class dynamically

Question

I have googled bit , but dint find way to unload dll using JNA ,from java Class. And as i am using dll to transfer data from usb device using this dll, i have to unload my dll from java class in order to re-use my usb device with same class without closing my whole program. here is how i load my dll using JNA

public interface UsbSensor extends Library {

        UsbSensor INSTANCE = (UsbSensor) Native.loadLibrary(
                (Platform.isWindows() ? "D:\\UsbDevice.dll" : "D:\\UsbDevice.dll"), UsbSensor.class);

        int SearchDevices();

        Pointer Startacquisition(String type);
}

and by

 UsbSensor sdll = UsbSensor.INSTANCE; 

Dll is loded. And here how i use my function

sdll.SearchDevices();
sdll.Startacquisition();

And now after using these function I must have to unload my dll in again load dll using above code. order reuse these function.

So how to unload dll dynamically Using JNA?

Answer 1

NativeLibrary.dispose() should do what you are looking for. NativeLibrary is a 1:1 representation of the native library you are using (and is used internally by Native.loadLibrary() anyway). So

1. null the reference returned by Native.loadLibrary() and
2. call NativeLibrary.dispose()

Answer 2

I had the same issue but using Native.dispose() did not help. The solution to my problem was this question and answer . It basically sets instance of the native library to null and calls the garbage collector.

Answer 3

你可以创建一个临时的类加载器，使用本机函数，null对类加载器的引用，它将与它加载的类/ dll一起符合GC的条件