jni ndk 入门

1. Linux环境模拟，下载sygwin 安装，选择devl 和shell -> install

sygwin 中的配置ndk环境，进入安装目录c:/cygwin64

etc/profile文件配置ndk的环境

//37行

  PATH="/usr/local/bin:/usr/bin:/cygdrive/d/android-ndk-r9d-windows-x86_64/android-ndk-r9d${PATH:+:${PATH}}"

2. 下载ndk

3. 开发,参考于ndk/sample/HelloJni

创建android 工程在JNTTest，在jni中创建3个文件

3.1 helo-jni.c中内容如下

/*

 * Copyright (C) 2009 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 *

 */

#include <string.h>

#include <jni.h>

/* This is a trivial JNI example where we use a native method

 * to return a new VM String. See the corresponding Java source

 * file located at:

 *

 *   apps/samples/hello-jni/project/src/com/example/hellojni/HelloJni.java

 */

jstring

Java_com_jun_jnitest_MainActivity_stringFromJNI( JNIEnv* env, jobject thiz )

{

 return (*env)->NewStringUTF(env, "Hello from JNI !  Compiled with ABI ");

}

3.2 Application.mk 内容如下：

APP_ABI := all

3.3 Android.mk

# Copyright (C) 2009 The Android Open Source Project

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#      http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

#

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := hello-jni

LOCAL_SRC_FILES := hello-jni.c

include $(BUILD_SHARED_LIBRARY)

3.4 java文件编辑

package com.jun.jnitest;

public class MainActivity extends Activity {

   

public native String  stringFromJNI();

   /* This is another native method declaration that is *not*

    * implemented by 'hello-jni'. This is simply to show that

    * you can declare as many native methods in your Java code

    * as you want, their implementation is searched in the

    * currently loaded native libraries only the first time

    * you call them.

    *

    * Trying to call this function will result in a

    * java.lang.UnsatisfiedLinkError exception !

    */

   public native String  unimplementedStringFromJNI();

 

//  静态代码块，先于构造函数执行,在此会对C/C++代码的库即：*.so文件进行加载

  static {

        //hello-jni 为在android.mk 中定义的名称

      System.loadLibrary("hello-jni");

    }

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

// System.out.println(stringFromJNI());

}

public void click(View view) {

                    //使用

Toast.makeText(this, stringFromJNI(), 0).show();

}

 

}

3.5 利用cygwin编译

cd 到当前android 工程目录下 /cygdrive/d/android/workspace/jnitest

Luv@Luv-PC /cygdrive/d/android/workspace/jnitest

$ ndk-build

Android NDK: WARNING: APP_PLATFORM android-19 is larger than android:minSdkVersion 8 in ./AndroidManifest.xml

[armeabi-v7a] Compile thumb  : hello-jni <= hello-jni.c

[armeabi-v7a] SharedLibrary  : libhello-jni.so

[armeabi-v7a] Install        : libhello-jni.so => libs/armeabi-v7a/libhello-jni.so

[armeabi] Compile thumb  : hello-jni <= hello-jni.c

[armeabi] SharedLibrary  : libhello-jni.so

[armeabi] Install        : libhello-jni.so => libs/armeabi/libhello-jni.so

[x86] Compile        : hello-jni <= hello-jni.c

[x86] SharedLibrary  : libhello-jni.so

[x86] Install        : libhello-jni.so => libs/x86/libhello-jni.so

[mips] Compile        : hello-jni <= hello-jni.c

[mips] SharedLibrary  : libhello-jni.so

[mips] Install        : libhello-jni.so => libs/mips/libhello-jni.so

3.6 运行

来自为知笔记(Wiz)