JNI 使用方法 Guide to JNI (Java Native Interface)

1. 创建 NativeMainJNI.java 类

/**
 * CSDN:http://blog.csdn.net/yin13753884368/article
 * Github:https://github.com/taxiao213
 */
public class NativeMainJNI {

 static {
 System.loadLibrary("native");
 }

 public static void main(String[] args) {
 new NativeMainJNI().sayHello();
 }
 public native void sayHello();

 public native void start(String fucntion, String json);
}

2.在命令行窗口生成 com_taxiao_cn_apple_jni_NativeMainJNI.h

javac -h . NativeMainJNI.java

3.com_taxiao_cn_apple_jni_NativeMainJNI.h

#include <jni.h>
/* Header for class com_taxiao_cn_apple_jni_NativeMainJNI */

#ifndef _Included_com_taxiao_cn_apple_jni_NativeMainJNI
#define _Included_com_taxiao_cn_apple_jni_NativeMainJNI
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_taxiao_cn_apple_jni_NativeMainJNI
 * Method:    sayHello
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_com_taxiao_cn_apple_jni_NativeMainJNI_sayHello
 (JNIEnv *, jobject);

/*
 * Class:     com_taxiao_cn_apple_jni_NativeMainJNI
 * Method:    start
 * Signature: (Ljava/lang/String;Ljava/lang/String;)V
 */
JNIEXPORT void JNICALL Java_com_taxiao_cn_apple_jni_NativeMainJNI_start
 (JNIEnv *, jobject, jstring, jstring);

#ifdef __cplusplus
}
#endif
#endif

4.com_taxiao_cn_apple_jni_NativeMainJNI.cpp

#include "com_taxiao_cn_apple_jni_NativeMainJNI.h"
#include <iostream>
#include <stdio.h>
/* Header for class com_taxiao_cn_apple_jni_NativeMainJNI */
using namespace std;

/*
 * Class:     com_taxiao_cn_apple_jni_NativeMainJNI
 * Method:    sayHello
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_com_taxiao_cn_apple_jni_NativeMainJNI_sayHello(JNIEnv * env, jobject obj)
{
 cout<< "Hello from C++ sayHello " <<endl;
}

/*
 * Class:     com_taxiao_cn_apple_jni_NativeMainJNI
 * Method:    start
 * Signature: (Ljava/lang/String;Ljava/lang/String;)V
 */
JNIEXPORT void JNICALL Java_com_taxiao_cn_apple_jni_NativeMainJNI_start(JNIEnv * env, jobject obj, jstring function, jstring str)
{
 cout<< "Hello from C++ start " <<endl;
}

不同的系统
Ubuntu version:

g++ -c -fPIC -I${JAVA_HOME}/include -I${JAVA_HOME}/include/linux com_taxiao_cn_apple_jni_NativeMainJNI.cpp -o com_taxiao_cn_apple_jni_NativeMainJNI.o

Windows version:

g++ -c -I%JAVA_HOME%\include -I%JAVA_HOME%\include\win32 com_taxiao_cn_apple_jni_NativeMainJNI.cpp -o com_taxiao_cn_apple_jni_NativeMainJNI.o

MacOS version:

g++ -c -fPIC -I${JAVA_HOME}/include -I${JAVA_HOME}/include/darwin com_taxiao_cn_apple_jni_NativeMainJNI.cpp -o com_taxiao_cn_apple_jni_NativeMainJNI.o

5.汇编 com_taxiao_cn_apple_jni_NativeMainJNI.cpp

g++ -c -fPIC -I ${JAVA_HOME}/include/ -I ${JAVA_HOME}/include/linux/ com_taxiao_cn_apple_jni_NativeMainJNI.cpp -o com_taxiao_cn_apple_jni_NativeMainJNI.o

不同的系统

Ubuntu version:

g++ -shared -fPIC -o libnative.so com_taxiao_cn_apple_jni_NativeMainJNI.o -lc

Windows version:

g++ -shared -o native.dll com_taxiao_cn_apple_jni_NativeMainJNI.o -Wl,--add-stdcall-alias

MacOS version:

g++ -dynamiclib -o libnative.dylib com_taxiao_cn_apple_jni_NativeMainJNI.o -lc

6.链接 生成 libnative.so

g++ -shared -fPIC -o libnative.so com_taxiao_cn_apple_jni_NativeMainJNI.o -lc

在这里插入图片描述

将生成的 libnative.so 库拷贝到 /home/build/workspace/hqq/vision/android_project/jni_project/apple

然后在此目录执行如下命令

7.运行 NativeMainJNI

java -cp . -Djava.library.path=/home/build/workspace/hqq/vision/android_project/jni_project/ndk_demo/app/src/main/java/com/taxiao/cn/jni/libnative com.taxiao.cn.apple.jni.NativeMainJNI

8.结果

java_13.png