Calling existing C functions with JNI

[sampalmer21]

I have a dll containing c functions which I cannot edit in any way. How do I call those functions using JNI without having to add the java generated header files/functions into the c file?

[JosAH]

I have a dll containing c functions which I cannot edit in any way. How do I call those functions using JNI without having to add the java generated header files/functions into the c file?

You never have to add anything to existing code. Let foo.h be the header file of
your existing code, containing:

[code=c]
#ifndef FOO_H
#define FOO_H
extern int foo();
#endif
[/code]

Generate a Java class like this:

[code=java]
public class FooWrapper {
static { // load the library
System.loadLibr ary("FooWrapper .dll");
}
native int fooWrapper();
}
[/code]

compile it and make the FooWrapper.h header file using the javah tool and the
compiled .class file. Next create your wrapper method:

[code=c]
#include <foo.h> /* the real function declaration */
#include <FooWrapper.h > /* the generated wrapper declaration */

/* definition of the wrapper */
jint fooWrapper( ...) {

/* your code here calling foo()
}
[/code]

Now compile your FooWrapper.c file, link your compiled c file to a .dll and voila.

kind regards,

Jos