Android NDK 开发(笔记一)

接引：Android NDK r7以上集成了cywin，在开发NDK时不用那么麻烦的在去下载与配置cywin.

Android NDK 开发步骤：

1. Eclipse 首先配置Ndk路径，Windows –>Preferences –>Android –>NDK ,指定NDK路径：如：D:\AndroidNDK\ndk-r10e

   

   如果在Windows – Preferences –>Android下没有看到NDK配置选项，那么请下载Eclipse–NDK插件，下载地址：http://pan.baidu.com/s/1dDXBKTN ，我是Win7 x64系统，所以请根据自己系统去下载相应的EclipseNdk插件。下载完成请将下载的xxxxxxxxxxxxndk.jar,拷贝，放到Eclipse根目录，如：D:\Androiddevelop\eclipse\plugins文件下，重启Eclipse就能看到了。

2. 新建Android project 取名，AndroidNDKDemo,新建包名com.jni,新建JNI.java,在JNI中声明需要调用的C方法。

   

3. 选择工程，右键选择 Android Tools –>Add Native Support…，建立取名为hello-jni.so的so库。点击 Finish。

   

   这时你会发现在工程目录下，多出了一个jni目录与obj目录，目录中有两个文件分别是：Android.mk,与一个 hello.cpp文件。我这里直接将hello.cpp文件换成hello.c文件了。

   

4. cmd 进入D:\workspace\AndroidJniTest\bin\

   javah -jni com.jni.JNI 生成hello.h文件。参考如图：

   

5. 根据生成的.h文件编译相关的hello.c文件。

   

   如果需要针对不同cpu生成不同规格下的libhello.so则需要在hello.c文件中进行判断

   hello.c

   jstring Java_com_patch_JNI_Hello(JNIEnv* env, jobject obj) {
   #if defined(__arm__)
   #if defined(__ARM_ARCH_7A__)
   #if defined(__ARM_NEON__)
   #if defined(__ARM_PCS_VFP)
   #define ABI "armeabi-v7a/NEON (hard-float)"
   #else
   #define ABI "armeabi-v7a/NEON"
   #endif
   #else
   #if defined(__ARM_PCS_VFP)
   #define ABI "armeabi-v7a (hard-float)"
   #else
   #define ABI "armeabi-v7a"
   #endif
   #endif
   #else
   #define ABI "armeabi"
   #endif
   #elif defined(__i386__)
   #define ABI "x86"
   #elif defined(__x86_64__)
   #define ABI "x86_64"
   #elif defined(__mips64)  /* mips64el-* toolchain defines __mips__ too */
   #define ABI "mips64"
   #elif defined(__mips__)
   #define ABI "mips"
   #elif defined(__aarch64__)
   #define ABI "arm64-v8a"
   #else
   #define ABI "unknown"
   #endif
   return (*env)->NewStringUTF(env, "Yes ,Hello from JNI !");
   

   }

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.c

    include $(BUILD_SHARED_LIBRARY)

Application.mk

内容：

    APP_ABI := all

1. Activity中调用：

   

2. 运行一下，如果编译成功你会发现libs目录结构发生了变化

   

效果: