Android Studio2.2 配置NDK

环境

• 主机:WIN10
• 开发环境:Android Studio2.2 Preview 3

步骤

• 安装NDK 
  打开Tools->Android->SDK Manager->SDK Tools选中LLDB和NDK，点击确认，软件会自动安装NDK。 
  

• 配置环境变量

  • 增加一项：NDK_ROOT，如：C:\soft\adt-bundle-windows-x86-20130911\sdk\ndk-bundle
  • 在path中增加%NDK_ROOT%

• 在main中新建文件夹jni 
  
• 新建hello-jni.c 
  函数需按照规则命名：Java_包名类名方法名
• /*
   * 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_bazhangkeji_MainActivity_stringFromJNI( JNIEnv* env,
  //                                                  jobject thiz )
  //{
  //    return (*env)->NewStringUTF(env, "Hello from JNI !");
  //}
  
  JNIEXPORT jstring JNICALL
  Java_com_bazhangkeji_demo01_MainActivity_stringFromJNI(JNIEnv *env, jobject instance) {
  //    // TODO
  //
  //
  //    return (*env)->NewStringUTF(env, returnValue);
      return (*env)->NewStringUTF(env, "Hello from JNI !");
  }
  

• 新建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)
  

• 在build.gradle中配置 
  配置好，make project即可生成.so文件在app\build\intermediates\ndk-build\debug\lib中。 
  增加语句：
• externalNativeBuild {
          ndkBuild {
              path file("src\\main\\jni\\Android.mk")
          }
      }
  

完整的代码：

apply plugin: 'com.android.application'
android {
    compileSdkVersion 24
    buildToolsVersion "24.0.0"
    defaultConfig {
        applicationId "com.bazhangkeji.demo01"
        minSdkVersion 15
        targetSdkVersion 24
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
//        ndk {
//            moduleName "libspeex"
//            cFlags "-std=c++11 -fexceptions"
//            ldLibs "log"
//            stl "gnustl_shared"
//            abiFilter "armeabi-v7a"
//        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    externalNativeBuild {
        ndkBuild {
            path file("src\\main\\jni\\Android.mk")
        }
    }
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:24.0.0'
    compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha3'
    compile 'com.android.support:design:24.0.0'
    testCompile 'junit:junit:4.12'
    androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.2'
    androidTestCompile 'com.android.support.test:runner:0.5'
    androidTestCompile 'com.androd.support:support-annotations:24.0.0'
}

• 在java层调用
• public class MainActivity extends AppCompatActivity {
  
      private static final int RECORDER_SAMPLERATE = 8000;
      private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
      private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
      private AudioRecord recorder = null;
      private Thread recordingThread = null;
      private boolean isRecording = false;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
          setSupportActionBar(toolbar);
          FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
          fab.setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View view) {
                  Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                          .setAction("Action", null).show();
              }
          });
          setButtonHandlers();
          enableButtons(false);
          int bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE,
                  RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING);
          System.out.println(stringFromJNI());
      }
      public native String stringFromJNI();
      public native String unimplementedStringFromJNI();
      static {
          System.loadLibrary("hello-jni");
      }