ubuntu编写jni并编译

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1. ubuntu14.04安装好jdk并设置java_home

2. 设置好android源码编译环境，主要是gcc和make

sudo apt-get install git-core gnupg flex bison gperf libsdl1.2-dev \ libesd0-dev libwxgtk2.8-dev squashfs-tools build-essential zip curl \ libncurses5-dev zlib1g-dev pngcrush schedtool libxml2 libxml2-utils \ xsltproc lzop libc6-dev schedtool g++-multilib lib32z1-dev lib32ncurses5-dev \ lib32readline-gplv2-dev gcc-multilib libswitch-perl \ libssl1.0.0 libssl-dev3. hadoop@hadoop-nb:~$ mkdir jni    hadoop@hadoop-nb:~$ cd jni    hadoop@hadoop-nb:~/jni$ mkdir com   hadoop@hadoop-nb:~/jni$ mkdir com/yf   hadoop@hadoop-nb:~/jni$ vi com/yf/JniTest.java内容如下:package com.yf;import java.lang.System;public class JniTest{static  {    System.loadLibrary("jni-test");}public static void main(String args[]) {    JniTest jniTest = new JniTest();    System.out.println(jniTest.get());    jniTest.set("hello jni world");}public native String get();public native void set(String str);}3.编译JniTest.java hadoop@hadoop-nb:~/jni$ javac com/yf/JniTest.java

4. 生成JNI头文件

hadoop@hadoop-nb:~/jni$ javah -classpath . com.yf.JniTest

生成h文件

hadoop@hadoop-nb:~/jni$ ls
com com_yf_JniTest.h

5. 编辑实现JNI方法的c++

hadoop@hadoop-nb:~/jni$ vi test.cpp
内容如下:

//test.cpp
#include "com_yf_JniTest.h"
#include <jni.h>
#include <stdio.h>

JNIEXPORT jstring JNICALL Java_com_yf_JniTest_get
(JNIEnv *env, jobject thiz){
printf("invoke get in c++\n");
return env->NewStringUTF("Hello from JNI !");
}

JNIEXPORT void JNICALL Java_com_yf_JniTest_set
(JNIEnv *env, jobject thiz, jstring string){
printf("invoke set from c++\n");
char* str = (char*)env->GetStringUTFChars(string,NULL);
printf("%s\n",str);
env->ReleaseStringUTFChars(string,str);
}

6.编译cpp文件，生成so库文件

hadoop@hadoop-nb:~/jni$ gcc -shared -I /home/hadoop/javaweb/jdk1.7.0_79/include -fPIC test.cpp -o lib/libjni-test.so

在lib目录下生成libjni-test.so文件

7. 运行整个程序并输出结果

hadoop@hadoop-nb:~/jni$ java -classpath . -Djava.library.path=lib com.yf.JniTest
invoke get in c++
Hello from JNI !
invoke set from c++
hello jni world

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