Hi!

I would like to load a DLL and unload a loaded DLL (probably not loaded by our code) using JNIWrapper.

I found the functions in kernel32.dll and tried to invoke those in order to load and unload.

I don't really want to use the DLL later, I just want to load it when I want and get rid of it when I want.

But it isn't working.

Code looks like this:

  private static void loadCitrixHookDll( ) {
    Pointer.Void retVal = new Pointer.Void( );

    try {
      Function.call( "Kernel32.dll", "LoadLibraryA", retVal, new Str( "twnhook.dll" ) );
    } catch( NoSuchFunctionException exception ) {
      exception.printStackTrace( );
    }

    System.out.println( "RetVal: " + retVal );
  }

  private static void unloadCitrixHookDll( ) {
    Pointer.Void retVal = new Pointer.Void( );

    try {
      Function.call( "Kernel32.dll", "GetModuleHandleA", retVal,
        new Str( "twnhook.dll" ) );
    } catch( NoSuchFunctionException exception ) {
      exception.printStackTrace( );
    }

    System.out.println( "RetVal: " + retVal );
    Int value = new Int( );

    try {
      Function.call( "Kernel32.dll", "FreeLibrary", value, retVal );
    } catch( NoSuchFunctionException exception ) {
      exception.printStackTrace( );
    }
  }

I tried various variations (like using Library and Function). In the end, the only way I could load the library in the end is System.load() or the DefaultLibraryLoader.

But how to unload again and how to find the handle?

Probably a stupid question, but hey, I am a Java programmer. If it cannot be done using JNIWrapper then we will have to resort to using a native DLL and JNI.

But I would prefer to handle that using JNIWrapper.

So, please, what am I doing wrong, or is it impossible?

Sascha Herrmann