Are there any good resources on the web to learn about JNI?

Depending upon what you are looking for, try out some of the following:

• Roedy Green maintains a useful resource at http://mindprod.com/jni.html
• JavaWorld Tip 17: http://www.javaworld.com/javatips/jw-javatip17.html
• JNI Tutorial trail: http://java.sun.com/docs/books/tutorial/native1.1/index.html
• CodeGuru JNI Resources: http://codeguru.earthweb.com/java/JNI/index.shtml
• JavaWorld JNI Tutorial: http://www.javaworld.com/javaworld/jw-10-1999/jw-10-jni.html