How to compile dynamic library for a JNI application on linux?

Question

I\'m using Ubuntu 10.10

So that\'s what I did.

Hello.java:

class Hello {
        public native void sayHello();

           


        

Answer 1

Finally my code works. This is hello.java

public class hello {
  public native void sayHello(int length) ;
  public static void main (String args[]) {
    String str = "I am a good boy" ;
    hello h = new hello () ;
    h.sayHello (str.length() ) ;
  }
  static {
    System.loadLibrary ( "hello" ) ;
  }
}

You should compile it as :

$ javac hello.java 

To create .h file you should run this command:

$ javah -jni hello

This is hello.h:

JNIEXPORT void JNICALL Java_hello_sayHello
(JNIEnv *, jobject, jint);

Here is hello.c:

#include
#include
#include "hello.h" 

JNIEXPORT void JNICALL Java_hello_sayHello
  (JNIEnv *env, jobject object, jint len) {
  printf ( "\nLength is %d", len ); }

To compile this and to create a shared library we have to run this command :

$ gcc -I/usr/lib/jvm/java-6-openjdk/include -o libhello.so -shared hello.c

Then finally run this one :

$ java -Djava.library.path=. hello