在学习JNI的过程中 使用NDK配置编译环境时报了一个异常：
Error:Execution failed for task ':app:compileDebugNdk'. > Error: Flag android.useDeprecatedNdk is no longer supported and will be removed in the next version of Android Studio. Please switch to a supported build system Consider using CMake or ndk-build integration. For more information, go to: https://d.android.com/r/studio-ui/add-native-code.html#ndkCompile To get started, you can use the sample ndk-build script the Android plugin generated for you at: D:\Workspace\Android\workselect\JNI\app\build\intermediates\ndk\debug\Android.mk Alternatively, you can use the experimental plugin: https://developer.android.com/r/tools/experimental-plugin.html To continue using the deprecated NDK compile for another 60 days, set android.deprecatedNdkCompileLease=1529135472909 in gradle.properties
1>使用Android SDK下载工具 CMake & LLDB大概意思是：android.useDeprecatedNdk不再支持了
/Users/apple/Desktop/AndroidJNITest/app/build/intermediates/ndk/debug/Android.mk
https://developer.android.com/r/tools/experimental-plugin.html
继续使用已弃用的NDK编译60天，设置 在gradle.properties原来在gradle3.0以上以前这种方法不在支持经过一番学习 我使用了CMake解决了这个问题：
2>在 app 工程下的 build.gradle 文件中添加节点
//配置Cmake运行参数,在defaultconfig节点下配置 defaultConfig{ externalNativeBuild { cmake { cppFlags "-frtti -fexceptions" } } }//关联CMake的程序清单文件,path 指向cmake文件路径，此处为项目工程根目录下。 externalNativeBuild { cmake { path "CMakeLists.txt" } }# For more information about using CMake with Android Studio, read the # documentation: https://d.android.com/studio/projects/add-native-code.html # Sets the minimum version of CMake required to build the native library. #CMakeLists.txt cmake_minimum_required(VERSION 3.4.1) # Creates and names a library, sets it as either STATIC # or SHARED, and provides the relative paths to its source code. # You can define multiple libraries, and CMake builds them for you. # Gradle automatically packages shared libraries with your APK. add_library( # Sets the name of the library. # 设置so文件名称. myso # Sets the library as a shared library. SHARED # 设置这个so文件为共享. # Provides a relative path to your source file(s). # 设置c文件的目录 src/main/jni/hello.c) #Searches for a specified prebuilt library and stores the path as a #variable. Because CMake includes system libraries in the search path by #default, you only need to specify the name of the public NDK library #you want to add. CMake verifies that the library exists before #completing its build. find_library( # Sets the name of the path variable. log-lib # Specifies the name of the NDK library that # you want CMake to locate. log ) #Specifies libraries CMake should link to your target library. You #can link multiple libraries, such as libraries you define in this #build script, prebuilt third-party libraries, or system libraries. target_link_libraries( # Specifies the target library. # 指定依赖库. myso # Links the target library to the log library # included in the NDK.关联日志记录库文件，在ndk目录中 ${log-lib} )
4>编写java类
package com.project.pulis.jni; public class JNI { static{ System.loadLibrary("myso");//在静态代码块中设置so库 } public native String sayHello(); }5>生成头文件
6>编写C代码
7>rebuild-project ---> make-porject
8>成功了会生成如下文件
9>实验结果再 MainActivity 添加代码
6>编写C代码
#include "com_project_pulis_jni_JNI.h"//导入头文件 //实现头文件里的代码 JNIEXPORT jstring JNICALL Java_com_project_pulis_jni_JNI_sayHello (JNIEnv *env, jobject jobj){ return (*env)->NewStringUTF(env,"HelloFrom JNI!"); }7>rebuild-project ---> make-porject
8>成功了会生成如下文件
9>实验结果再 MainActivity 添加代码
public class MainActivity extends AppCompatActivity { private TextView textView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textView=findViewById(R.id.text); JNI jni=new JNI(); String hello=jni.sayHello(); textView.setText(hello); } }运行结果:
文章来源: 使用CMake编译JNI的C文件