At
the time of this writing, Microsoft does not support JNI, but provides
proprietary support to call non-Java code. This support is built into the
compiler, the Microsoft JVM, and external tools. The features described in this
section will work only if your program was compiled using the Microsoft Java
compiler and run on the Microsoft Java Virtual Machine. If you plan to
distribute your application on the Internet, or if your Intranet is built on
different platforms, this can be a serious issue.
The
Microsoft interface to Win32 code provides three ways to connect to Win32:
J/Direct:
A way to easily call Win32 DLL functions, with some limitations.
Raw
Native Interface (RNI)
:
You can call Win32 DLL functions, but you must then handle garbage collection.
Java/COM
integration
:
You can expose or call COM services directly from Java.
I’ll
cover all three techniques in the following sections.
At
the time of writing, these features were tested on the Microsoft SDK for Java
2.0 beta 2, which was downloaded (with a painful process they call
“Active Setup”) from the Microsoft Web site. The Java SDK is a set
of command-line tools, but the compilation engine can be easily plugged into
the Developer Studio environment, allowing you to use Visual J++ 1.1 to compile
Java 1.1 code.