尽管已正确设置，但Android Studio NDK不兼容

编程问答 2022-08-13

问题描述

我正在尝试将OpenCv与android studio集成，并且在此过程中我面临着NDK问题。 NDK在项目结构中始终保持未选中状态。由于路径未提及，头文件始终不可用。我试图解决这个问题已经有好几天了，但是如果有人愿意，我将无法找到上述解决方案。 NDK无法连接，尽管已经尝试了多种方法来集成NDK。 我使用了所有可能的方式来集成NDK，并采取了可能的措施来复制我的需求，但是没有任何效果。 我已经看到其他人如何尝试解决此问题，但没有一个对我有用。

以下是我的代码 CMakeLists.txt文件

cmake_minimum_required(VERSION 3.4.1)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")

include_directories(${OpenCV_DIR}/jni/include)

add_library( lib_opencv SHARED IMPORTED )

set_target_properties(lib_opencv PROPERTIES IMPORTED_LOCATION ${OpenCV_DIR}/libs/${ANDROID_ABI}/libopencv_java4.so)

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             native-lib.cpp )

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 )

target_link_libraries( # Specifies the target library.
                       native-lib

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib}

                       lib_opencv)

native-lib.cpp 

#include <jni.h>

在此处找不到jni.h文件，因此JNIEXPORT和JNICALL也保持隐藏状态。

build.gradle（app）

apply plugin: 'com.android.application'

android {
    compileSdkVersion 29

    defaultConfig {
        applicationId "com.karuneshpalekar.copencv"
        minSdkVersion 21
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags "-frtti -fexceptions"
                abiFilters 'x86','x86_64','armeabi-v7a','arm64-v8a'
                arguments "-DOpenCV_DIR=" + opencvsdk + "/sdk/native"
            }
        }

        ndk {
            moduleName "test"
            cFlags "-std=c++11 -fexceptions"
            stl "gnustl_shared"
        }


    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'),'proguard-rules.pro'
        }
    }
    externalNativeBuild {
        cmake {
            path "src/main/cpp/CMakeLists.txt"
            version "3.10.2"
        }
    }

    packagingOptions {
        pickFirst 'lib/armeabi-v7a/libopencv_java4.so'
        pickFirst 'lib/arm64-v8a/libopencv_java4.so'
        pickFirst 'lib/x86/libopencv_java4.so'
        pickFirst 'lib/x86_64/libopencv_java4.so'
    }


}

dependencies {
    implementation filetree(dir: "libs",include: ["*.jar"])
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.0'
    implementation project(path: ':java')
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

}

build.gradle（java）

apply plugin: 'com.android.library'

println "OpenCV: " + project.buildscript.sourceFile

android {
    compileSdkVersion 29
    //buildToolsversion "x.y.z" // not needed since com.android.tools.build:gradle:3.0.0

    defaultConfig {
        minSdkVersion 21
        targetSdkVersion 29
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'),'proguard-rules.txt'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_6
        targetCompatibility JavaVersion.VERSION_1_6
    }

    sourceSets {
        main {
            jniLibs.srcDirs = ['src/main/jniLibs']
            java.srcDirs = ['src/main/java']
            aidl.srcDirs = ['src']
            res.srcDirs = ['/build/master_pack-android/opencv/modules/java/android_sdk/android_gradle_lib/res']
            manifest.srcFile 'java/AndroidManifest.xml'
        }
    }
}

dependencies {
}

谢谢您的帮助 我有Ndk-rc21和Android Studio AGP版本4.0.1和Gradle Versopion 6.1.1

解决方法

如何在NDK（v19）中使用OpenCV SDK（v4.4）

使用app模块创建一个Android Studio项目。

settings.gradle 

include ':app'

build.gradle 

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:4.0.1"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

在local.properties文件中设置Android SDK和NDK（v19）路径。

sdk.dir=/home/USER/Android/Sdk
ndk.dir=/home/USER/Android/Sdk/ndk/android-ndk-r19c

指定主cmake构建脚本文件的路径，要使用的cmake版本以及要在app/build.gradle文件中编译的Android ABI。

apply plugin: 'com.android.application'

android {
    compileSdkVersion 29

    defaultConfig {
        minSdkVersion 23
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        ndk {
            abiFilters "arm64-v8a","armeabi-v7a"
        }
    }

    externalNativeBuild {
        cmake {
            path "src/main/cpp/CMakeLists.txt"
            version "3.10.2"
        }
    }
}

dependencies {
    ...
}

现在，我们需要来自OpenCV Android SDK的头文件和库。因此，请从https://opencv.org/releases/

下载并解压缩适用于Android的OpenCV SDK（v4.4）软件包。

按如下所示将OpenCV标头文件和库从提取的包复制到Android Studio项目。

  1. 将OpenCV-android-sdk/sdk/native/staticlibs/*复制到app/src/main/cpp/opencv/staticlibs/

  2. 将OpenCV-android-sdk/sdk/native/3rdparty/*复制到app/src/main/cpp/opencv/3rdparty/

  3. 将OpenCV-android-sdk/sdk/native/jni/include/*复制到app/src/main/cpp/opencv/include/

在项目中创建以下cmake文件。

app/src/main/cpp/opencv/opencv.cmake 

set( CURRENT_DIR ${CMAKE_CURRENT_LIST_DIR} )
set( OPENCV_INC_DIR ${CURRENT_DIR}/include )
set( OPENCV_LIBS_DIR ${CURRENT_DIR}/staticlibs/${ANDROID_ABI} )
set( THIRD_PARTY_LIBS_DIR ${CURRENT_DIR}/3rdparty/libs/${ANDROID_ABI} )

# Add opencv libs

set( lib_name opencv_calib3d )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_dnn )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_features2d )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_flann )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_gapi )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_highgui )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_imgcodecs )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_imgproc )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_ml )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_objdetect )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_photo )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_stitching )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_video )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_videoio )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

set( lib_name opencv_core )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${OPENCV_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND OPENCV_LIBS ${lib_name} )

# Add 3rd-party libs

set( lib_name ade )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name cpufeatures )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name IlmImf )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name ittnotify )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name libjasper )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name libjpeg-turbo )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name libpng )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name libprotobuf )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name libtiff )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name libwebp )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name quirc )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name tbb )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

set( lib_name tegra_hal )
add_library( ${lib_name} STATIC IMPORTED )
set_target_properties( ${lib_name} PROPERTIES IMPORTED_LOCATION "${THIRD_PARTY_LIBS_DIR}/lib${lib_name}.a" )
list( APPEND THIRD_PARTY_LIBS ${lib_name} )

在主cmake构建脚本中包含opencv.cmake文件，设置OpenCV包含目录，并按如下所示链接库。

app/src/main/cpp/CMakeLists.txt 

cmake_minimum_required(VERSION 3.4.1)

include( opencv/opencv.cmake )

find_library( log-lib log )
find_library( android-lib android )
find_library( jnigraphics-lib jnigraphics )
find_library( z-lib z )

add_library( native-lib SHARED
    native-lib.cpp
)

target_include_directories( native-lib PRIVATE
    ${OPENCV_INC_DIR}
)

target_link_libraries( native-lib
    ${log-lib}
    ${android-lib}
    ${jnigraphics-lib}
    ${OPENCV_LIBS}
    ${THIRD_PARTY_LIBS}
    ${z-lib}
)

现在，您可以在C ++源文件中使用OpenCV API。

app/src/main/cpp/native-lib.cpp 

#include <jni.h>
#include <opencv2/core.hpp>

using namespace cv;

Mat matImage;
,

我遇到的问题不是NDK工具，而是我放置它的目录。

文件名之间存在空格，导致错误，例如“用户空间名”。例如：C：/ User / Elon Musk / SDK / ndk

在Android Studio lint显示警告后，我纠正了我的这个错误。

我更改了Android SDK目录的位置，然后重新运行代码，问题已解决。

根据Lakindu的上述回答，无需降级Ndk库，只需确保将NDK放在正确的位置即可。

也不要忘记在项目结构中添加NDK工具，您可以通过同时单击Ctrl + Shift + Alt + S来找到。

android-ndkc++javajavajava-native-interfacendk-build