You’ll have to install a 32bit JVM and you will be able to run your code.
If you are going to distribute your application, you will want to build both 32bit and 64bit versions of your DLL. Then use the following technique to have the proper DLL loaded regardless of your customers arch. Append either a 32 or a 64 (MyJniDLL32.dll & MyJniDLL64.dll) to your generated output file.
String archDataModel = System.getProperty("sun.arch.data.model");
System.loadLibrary(libraryName+archDataModel);