JNI really consists of two parts -- the ability to implement Java methods using native code, and the "Invocation API,"
which allows a native application to embed the Java VM. We're going to focus on the first approach, so our programs will
start as Java programs which use native code to implement some methods.
Native methods can be static or non-static. Since our Hello World method will be very procedural, we'll
go ahead and make it static.
The general steps required to implement our example will be:
- Create a Java class with a
native method, and compile it,
- Use the
javah tool to generate a C header file for the class,
- Write the C code implementing the method, compile it, and link it into a DLL,
- Insert code into our Java program telling it to load the DLL,
- Enable our Java program to find the DLL,
- Execute our Java program,
- Read
Hello World in the console window.