JNI、JNA 入门教程

清疚 2022-04-17 01:40 896阅读 0赞

# 一、JNI 入门教程 #

## 1.编写java测试类 ##

package com.liu.jni;

public class JNILibrary \{

public native static void show();

public native static int calc(int a, int b);

static \{      
        System.loadLibrary("libshared\_jni");  
    \}  
\}

package com.liu.jni;

public class JNITest \{

public static void main(String\[\] args) \{  
        JNILibrary.show();  
        System.out.println(JNILibrary.calc(3, 5));  
    \}  
\}

## 2.利用java类生成C头文件 ##

cmd进入class文件根目录：

cd D:\\jps-workspace\\jni\_jna\\target\\classes

执行命令：

javah -classpath . -jni com.liu.jni.JNILibrary

重命名com.liu.jni.JNILibrary.h为JNILibrary.h

## 3.编译生成C++动态库 ##

创建动态库project：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RvbnlfMzI4NDI3Njg1_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RvbnlfMzI4NDI3Njg1_size_16_color_FFFFFF_t_70 1][]

复制JNILibrary.h到C++动态库project:

![20181111115724658.png][]

JNILibrary.h代码：

/\* DO NOT EDIT THIS FILE - it is machine generated \*/  
\#include <jni.h>  
/\* Header for class com\_liu\_jni\_JNILibrary \*/

\#ifndef \_Included\_com\_liu\_jni\_JNILibrary  
\#define \_Included\_com\_liu\_jni\_JNILibrary  
\#ifdef \_\_cplusplus  
extern "C" \{  
\#endif  
/\*  
 \* Class:     com\_liu\_jni\_JNILibrary  
 \* Method:    show  
 \* Signature: ()V  
 \*/  
JNIEXPORT void JNICALL Java\_com\_liu\_jni\_JNILibrary\_show  
  (JNIEnv \*, jclass);

/\*  
 \* Class:     com\_liu\_jni\_JNILibrary  
 \* Method:    calc  
 \* Signature: (II)I  
 \*/  
JNIEXPORT jint JNICALL Java\_com\_liu\_jni\_JNILibrary\_calc  
  (JNIEnv \*, jclass, jint, jint);

\#ifdef \_\_cplusplus  
\}  
\#endif  
\#endif

JNIShared.cc代码：

\#include <iostream>  
\#include "JNILibrary.h"

using namespace std;

JNIEXPORT void JNICALL Java\_com\_liu\_jni\_JNILibrary\_show(JNIEnv \*, jclass) \{  
    cout << "JNI Shared Library." << endl;  
\}

JNIEXPORT jint JNICALL Java\_com\_liu\_jni\_JNILibrary\_calc(JNIEnv \*, jclass,  
        jint a, jint b) \{  
    return a + b;  
\}

然后编译生成动态库：

![2018111112025262.png][]

## 4.添加动态库到jni\_jna ##

复制libshared\_jni.dll到jni\_jna工程![2018111112061424.png][]目录

然后设置动态库位置：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RvbnlfMzI4NDI3Njg1_size_16_color_FFFFFF_t_70 2][]

## 5.测试JNITest ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RvbnlfMzI4NDI3Njg1_size_16_color_FFFFFF_t_70 3][]

# 二、JNA入门教程 #

## 1.编写java测试类 ##

package com.liu.jna;

import com.sun.jna.Library;  
import com.sun.jna.Native;

public interface JNALibrary extends Library \{

JNALibrary INSTANCE = (JNALibrary) Native.loadLibrary("libshared\_jna", JNALibrary.class);

void show();

int calc(int a, int b);  
\}

package com.liu.jna;

public class JNATest \{

public static void main(String\[\] args) \{  
        JNALibrary.INSTANCE.show();  
        System.out.println(JNALibrary.INSTANCE.calc(3, 5));  
    \}  
\}

## 2.编译生成C++动态库 ##

创建动态库project同上

JNAShared.cc代码：

\#include <iostream>

using namespace std;

extern "C"  \_\_declspec(dllexport) void show();

extern "C"  \_\_declspec(dllexport) int calc(int a, int b);

void show() \{  
    cout << "JNA Shared Library." << endl;  
\}

int calc(int a, int b) \{  
    return a + b;  
\}

然后编译生成动态库：

![20181111124713210.png][]

## 3.添加动态库到jni\_jna ##

复制libshared\_jna.dll到jni\_jna工程![2018111112061424.png][]目录

## 4.测试JNATest ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RvbnlfMzI4NDI3Njg1_size_16_color_FFFFFF_t_70 4][]

实例源码：

[https://download.csdn.net/download/tony\_328427685/10777544][https_download.csdn.net_download_tony_328427685_10777544]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RvbnlfMzI4NDI3Njg1_size_16_color_FFFFFF_t_70 1]: /images/20220417/74d1338a0aec4e12a0df283220677e41.png
[20181111115724658.png]: /images/20220417/af34b561e02a459598c37704e7f35546.png
[2018111112025262.png]: /images/20220417/b57ce43592724d8c9021d2b51fd5b567.png
[2018111112061424.png]: /images/20220417/5f060628254c4b18894bce1af19411e4.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RvbnlfMzI4NDI3Njg1_size_16_color_FFFFFF_t_70 2]: /images/20220417/56d488f567ac43fa9a8a825fbb78397f.png
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[20181111124713210.png]: /images/20220417/18b037cbfdfc4531a12881007c487d31.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RvbnlfMzI4NDI3Njg1_size_16_color_FFFFFF_t_70 4]: /images/20220417/cee1e3bfc47647968b54d8ec0500fc11.png
[https_download.csdn.net_download_tony_328427685_10777544]: https://download.csdn.net/download/tony_328427685/10777544