[移动开发]android NDK JNI配置

android NDK JNI配置

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首先配置好android SDK 以及JNI

使用编译器android sudo

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新建项目-基础配置阶段一

1. 新建项目 选择project视图

2. 新建JNI
   
   

3. 在文件夹中创建一个Android.mk文件 （就是jni所在路径的makefile）写入一下内容

   LOCAL_PATH:=$(call my-dir)
   
   include $(CLEAR_VARS)
   
   #libtestjni.so
   LOCAL_MODULE := testjni
   LOCAL_SRC_FILES := test.cpp 
   LOCAL_LDLIBS := -llog
   
   include $(BUILD_SHARED_LIBRARY)
   

4. 在app的build.gradle中的android 范围内加入

   	sourceSets {
           main.jniLibs {
               //表示生产的so文件所在路径在什么位置
               source {
                   srcDirs = ['../libs']
               }
           }
       }
   

5. 删除 main { jni.srcDirs = [‘src/main/jni’, ‘…/JNI/’] }

6. 在JNI中创建一个test.cpp

   void testJni_Hello()
   {
       return;
   }
   

7. 使用Windows PowerShell （win10自带工具）

   cd JNI目录

   ndk-build.cmd

运行示例：

PS C:\Users\Daidenghui> cd E:\02course\MyApplication\MyApplication09\JNI
PS E:\02course\MyApplication\MyApplication09\JNI> ndk-build.cmd
Android NDK: APP_PLATFORM not set. Defaulting to minimum supported version android-14.
[arm64-v8a] Compile++ : testjni <= test.cpp
[arm64-v8a] StaticLibrary : libstdc++.a
[arm64-v8a] SharedLibrary : libtestjni.so
[arm64-v8a] Install : libtestjni.so => libs/arm64-v8a/libtestjni.so
[x86_64] Compile++ : testjni <= test.cpp
[x86_64] StaticLibrary : libstdc++.a
[x86_64] SharedLibrary : libtestjni.so
[x86_64] Install : libtestjni.so => libs/x86_64/libtestjni.so
[mips64] Compile++ : testjni <= test.cpp
[mips64] StaticLibrary : libstdc++.a
[mips64] SharedLibrary : libtestjni.so
[mips64] Install : libtestjni.so => libs/mips64/libtestjni.so
[armeabi-v7a] Compile++ thumb: testjni <= test.cpp
[armeabi-v7a] StaticLibrary : libstdc++.a
[armeabi-v7a] SharedLibrary : libtestjni.so
[armeabi-v7a] Install : libtestjni.so => libs/armeabi-v7a/libtestjni.so
[armeabi] Compile++ thumb: testjni <= test.cpp
[armeabi] StaticLibrary : libstdc++.a
[armeabi] SharedLibrary : libtestjni.so
[armeabi] Install : libtestjni.so => libs/armeabi/libtestjni.so
[x86] Compile++ : testjni <= test.cpp
[x86] StaticLibrary : libstdc++.a
[x86] SharedLibrary : libtestjni.so
[x86] Install : libtestjni.so => libs/x86/libtestjni.so
[mips] Compile++ : testjni <= test.cpp
[mips] StaticLibrary : libstdc++.a
[mips] SharedLibrary : libtestjni.so
[mips] Install : libtestjni.so => libs/mips/libtestjni.so
PS E:\02course\MyApplication\MyApplication09\JNI>

阶段二

1. 在在src中 跟Activity同一层路径 创建一个 专门调用JNI的类 OBOJNI.class

   //专门调用jni C++接口的类
   public class OBOJNI {
   
   
       public static OBOJNI getInstance() {
           if (instance == null) {
               instance = new OBOJNI();
           }
   
           return instance;
       }
   
       private static  OBOJNI instance = null;
   
   
       //提供一个调用JNI接口的成员方法
       public native void hello_jni();
   
   
       //加载cpp给提供的 动态库
       static {
           System.loadLibrary("testjni"); //libtestjni.so  testjni要和Android.mk里面的模块名字是一样的
       }
   
   }
   

2. 使用 Windows PowerShell 进入java目录

   然后执行javah -jni com.你的包名.OBOJNI
   运行示例：

   PS E:\02course\MyApplication\MyApplication09\JNI> cd E:\02course\MyApplication\MyApplication09\app\src\main\java
   PS E:\02course\MyApplication\MyApplication09\app\src\main\java> ls

   目录: E:\02course\MyApplication\MyApplication09\app\src\main\java
   

   Mode LastWriteTime Length Name

   ---

   d----- 2021/10/15 17:32 com

   PS E:\02course\MyApplication\MyApplication09\app\src\main\java> javah -jni com.ddh.dai.myapplication09.OBOJNI
   错误: 编码GBK的不可映射字符
   错误: 编码GBK的不可映射字符
   错误: 编码GBK的不可映射字符
   错误: 编码GBK的不可映射字符

   成功后会多一个文件
   

3. 将标注部分加入test.cpp中
   

   修改test.cpp为

   //
   // Created by Daidenghui on 2021/10/15.
   //
   
   #include <jni.h>
   #include <android/log.h>
   
   
   void testJni_Hello()
   {
       __android_log_print(ANDROID_LOG_ERROR,"testjni", "JNI: I am OK");
       return;
   }
   
   #ifdef __cplusplus
   extern "C" {
   #endif
   /*
    * Class:     com_ddh_dai_myapplication09_OBOJNI
    * Method:    hello_jni
    * Signature: ()V
    */
   JNIEXPORT void JNICALL Java_com_ddh_dai_myapplication09_OBOJNI_hello_1jni
   (JNIEnv *ev, jobject){
       testJni_Hello();
   }
   
   #ifdef __cplusplus
   }
   #endif
   
   

4. 再次使用Windows PowerShell进入JNI目录

   执行：ndk-bulid.com

运行示例：

PS E:\02course\MyApplication\MyApplication09\JNI> cd E:\02course\MyApplication\MyApplication09\JNI
PS E:\02course\MyApplication\MyApplication09\JNI> ndk-build.cmd
[arm64-v8a] Compile++ : testjni <= test.cpp
[arm64-v8a] SharedLibrary : libtestjni.so
[arm64-v8a] Install : libtestjni.so => libs/arm64-v8a/libtestjni.so
[x86_64] Compile++ : testjni <= test.cpp
[x86_64] SharedLibrary : libtestjni.so
[x86_64] Install : libtestjni.so => libs/x86_64/libtestjni.so
[mips64] Compile++ : testjni <= test.cpp
[mips64] SharedLibrary : libtestjni.so
[mips64] Install : libtestjni.so => libs/mips64/libtestjni.so
[armeabi-v7a] Compile++ thumb: testjni <= test.cpp
[armeabi-v7a] SharedLibrary : libtestjni.so
[armeabi-v7a] Install : libtestjni.so => libs/armeabi-v7a/libtestjni.so
[armeabi] Compile++ thumb: testjni <= test.cpp
[armeabi] SharedLibrary : libtestjni.so
[armeabi] Install : libtestjni.so => libs/armeabi/libtestjni.so
[x86] Compile++ : testjni <= test.cpp
[x86] SharedLibrary : libtestjni.so
[x86] Install : libtestjni.so => libs/x86/libtestjni.so
[mips] Compile++ : testjni <= test.cpp
[mips] SharedLibrary : libtestjni.so
[mips] Install : libtestjni.so => libs/mips/libtestjni.so

然后运行即可

看到输出就表示成功

end

每次修改.cpp文件后都需要使用Windows PowerShell进入JNI目录执行：ndk-bulid.com