How to handle .so libs in Java Bindings Library?

I'm trying to create a Java Bindings Library using a jar file with referenced .so lib. My binding project's tree looks like this:

Jars |=AboutJars.txt |=pdfviewer.jar libs |=armeabi |==librdpdf.so |=armeabi-v7a |==librdpdf.so |=x86 |==librdpdf.so |....

I set all libs' build actions to be EmbeddedNativeLibrary and jar to be EmbeddedJar. My application project can use all classes defined in the jar and can be built and deployed without error.

However, when it fails to execute the java code that makes a JNI call. "java.lang.UnsatisfiedLinkError: Native method not found:" as shows in console.

What can I do to make it work?

I'm using Xamarin.Android 4.8 on Visual Studio 2012.

Thank you