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
