Hi,

I don't know of any specific Eclipse plug-ins you can install to make things
easier, but once you have a C development environment and a Java SDK, you
can do JNI.

The process is generally:
1) Write your .java with the methods you want to delegate to external
libraries marked as "native".
2) From these .javas, run javah -jni MyClass.java -o MyClass.h to generate
the (C) header files for your native interface
3) Write the .c corresponding to the .h which actually makes the call to
the native library, and
4) Compile the cs into a .dll (or .so), linking in your native library, add
a loadLibrary in your java, and make sure the so is available at runtime to
the jvm, and you're done.

Cheers,
Dave.