JNA简单范例

#ifndef __JNATEST_H__
#define __JNATEST_H__
#define LOG_HERE() printf("%s-%d\n", __func__, __LINE__)
void test_jna();
#endif

#include <stdio.h>
#include "jnatest.h"
void test_jna()
{
    LOG_HERE();
    printf("called from JAVA\n");
}
JAVA代码
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Platform;
public class JnaTest
{
  //继承Library，用于加载库文件  
  public interface CLibrary extends Library
    {
  CLibrary INSTANCE = (CLibrary) Native.loadLibrary(
            (Platform.isWindows() ? "msvcrt" : "c"), CLibrary.class);
  // 声明一个跟C语言的printf()一样的方法，
  void printf(String format, Object... args);
  } 
  public interface TestLibrary extends Library
    {
  TestLibrary INSTANCE = (TestLibrary) Native.loadLibrary("jnatest", TestLibrary.class);
        void test_jna();
  } 
  public static void main(String[] args)
    {
  //调用  
  CLibrary.INSTANCE.printf("From JAVA To C, year=%d\n", 2022);
        TestLibrary.INSTANCE.test_jna();
  }
}

sudo apt install -y openjdk-8-jdk
sudo apt install -y libjna-java
sudo apt install -y libjna-platform-java

gcc -fPIC -shared -o libjnatest.so jnatest.c
sudo ldconfig
javac -extdirs /usr/share/java JnaTest.java

USJ_DIR=/usr/share/java
CLASS_DIRS=.
CLASS_DIRS=${CLASS_DIRS}:${USJ_DIR}/jna.jar
CLASS_DIRS=${CLASS_DIRS}:${USJ_DIR}/jna-platform.jar
java  \
    -cp ${CLASS_DIRS} \
    JnaTest