JNI整理_helloworld(1)-优快云博客

本文链接：https://blog.youkuaiyun.com/wxm_linux/article/details/6399231

本文介绍了一个简单的JNI示例，包括在Windows和Linux环境下设置环境变量、编译Java代码、生成JNI头文件、编写C代码实现本地方法并进行链接，最终运行Java程序的过程。

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一环境及编译

1.安装

(1)JDK.(window下直接运行;linux下直接解压到任务一个目录就行);

(2)环境变量

<1>windows

可以写一个批处理文件

我经常用下面一个.

@echo off set include=F:/VC/INCLUDE;F:/masm32/INCLUDE; set lib=F:/VC/LIB;F:/masm32/LIB;%lib% set lib="C:/Program Files/Java/jdk1.6.0_15/lib";%lib% set include="C:/Program Files/Java/jdk1.6.0_15/include";%include% set path=F:/VC/BIN;F:/VC/DLL;F:/masm32/BIN;%path% set path=.;"C:/Program Files/Java/jdk1.6.0_15/bin";%path% set classpath=.;"C:/Program Files/Java/jdk1.6.0_15/lib";%classpath% set path="C:/Program Files/java/jdk1.6.0_15/jre/bin/client";%path% set path="C:/Program Files/java/jdk1.6.0_15/jre/bin/server";%path% @echo on

<2>linux

在.bashrc中加入下面几行(根据安装路径):

export PATH=/usr/local/java/jdk1.6.0_25/bin:$PATH export classpath=/usr/local/java/jdk1.6.0_25/lib:$PATH export LD_LIBRARY_PATH=.:$(LD_LIBRARY_PATH)

2.编译

(1)HelloWorld.java

class HelloWorld { public native void displayHelloWorld(); static { System.loadLibrary("hello"); } public static void main(String[] args) { new HelloWorld().displayHelloWorld(); } }

(2)编译

<1>windows

1' javac HelloWorld.java 生成HelloWorld.java

2' 生成jni头文件

javah -jni HelloWorld

如:(HelloWorld.h)

/* DO NOT EDIT THIS FILE - it is machine generated */ #include <jni.h> /* Header for class HelloWorld */ #ifndef _Included_HelloWorld #define _Included_HelloWorld #ifdef __cplusplus extern "C" { #endif /* * Class: HelloWorld * Method: displayHelloWorld * Signature: ()V */ JNIEXPORT void JNICALL Java_HelloWorld_displayHelloWorld (JNIEnv *, jobject); #ifdef __cplusplus } #endif #endif

3' 编写本地方法

hello.c

#include <jni.h> #include "HelloWorld.h" JNIEXPORT void JNICALL Java_HelloWorld_displayHelloWorld(JNIEnv *env, jobject obj) { printf("Hello world!/n"); return; }

4' 编译

cl /c hello.c

link /dll hello.obj

这样就生成了hello.dll

5' 运行

java HelloWorld

<2>linux

代码都一样,编译时不一样.

Makefile如下:

JNI_INCLUDE1=/usr/local/java/jdk1.6.0_25/include JNI_INCLUDE2=/usr/local/java/jdk1.6.0_25/include/linux CC=gcc default:libhello.so libhello.so:hello.o $(CC) -shared -fPIC $< -o $@ .c.o: $(CC) -I$(JNI_INCLUDE1) -I$(JNI_INCLUDE2) -c $< -o $@ clean: rm -rf *.so rm -rf *.o