linux 下 swig 将c代码包装成java

环境

ubuntu linux

swig 4.0.2

gcc 9.3.0

jdk jdk1.8.0_321

准备example.c 文件

$ vi example.c

#include <time.h>
double My_variable = 3.0;

int fact(int n){
    if (n <=1) return 1;
    else return n*fact(n-1);
}

int my_mod(int x, int y){
    return (x%y);
}

char *get_time(){
    time_t ltime;
    time(&ltime);
    return ctime(&ltime);
}

准备example.i文件

$ vi example.i

%module example
%{
extern double My_variable;
extern int fact(int n);
extern int my_mod(int x, int y);
extern char *get_time();
%}
extern double My_variable;
extern int fact(int n);
extern int my_mod(int x, int y);
extern char *get_time();

$ swig -java example.i

$ locate jni.h
/home/mike/.local/share/Trash/files/jdk/jdk1.8.0_321/include/jni.h
/usr/java/jdk1.8.0_321/include/jni.h

$ locate jni_md.h
/home/mike/.local/share/Trash/files/jdk/jdk1.8.0_321/include/linux/jni_md.h
/usr/java/jdk1.8.0_321/include/linux/jni_md.h

$ gcc -fpic -c example.c example_wrap.c -I/usr/java/jdk1.8.0_321/include/ -I/usr/java/jdk1.8.0_321/include/linux/

$ gcc -shared example.o  example_wrap.o -o libexample.so

$ vi main.java

public class main {
   public static void main(String argv[]) {
     System.loadLibrary("example");
     System.out.println(example.getMy_variable());
     System.out.println(example.fact(5));
     System.out.println(example.get_time());
   }
 }

$ javac main.java

$ java main
Exception in thread "main" java.lang.UnsatisfiedLinkError: no example in java.library.path
    at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1860)
    at java.lang.Runtime.loadLibrary0(Runtime.java:871)
    at java.lang.System.loadLibrary(System.java:1124)
    at main.main(main.java:3)

$ java -Djava.library.path=. main
3.0
120
Wed Feb 16 11:56:39 2022