1.在android studio中的配置

1在android studio中创建 Native C++的项目

创建支持C++项目.png

将CMakelists.txt文件移动到app目录下

image.png

到opencv官方下载android 的sdk 到github上下载
opencv github地址
https://opencv.org/releases/#

将android sdk解压将 /根目录/sdk/native/lib下的所有文件（so），复制到android studio项目的jniLibs目录下,也将 include/opencv2目录复制到这里

image.png

so所在地址

C文件所在地址.png

修改Cmake中的配置项

# 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.

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.

#支持-std=gnu++11
if(CMAKE_COMPILER_IS_GNUCXX)
    set(CMAKE_CXX_FLAGS "-std=c++11 ${CMAKE_CXX_FLAGS}")
    message(STATUS "optional:-std=c++11")
endif(CMAKE_COMPILER_IS_GNUCXX)
#set(CMAKE_VERBOSE_MAKEFILE on)
#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")
#配置加载native依赖
#include_directories(${pathToOpenCv}/sdk/native/jni/include)
include_directories(src/main/cpp/include)
set(distribution_DIR ${CMAKE_SOURCE_DIR}/../../../../src/main/cpp)

set(CURRENT_DIR ${CMAKE_SOURCE_DIR})
# 在Gradle Console输出信息
# CMAKE_SOURCE_DIR:
message("CURRENT_DIR:" ${CMAKE_SOURCE_DIR})

#动态方式加载
add_library(lib_opencv STATIC IMPORTED ) #表示创建一个导入库，静态方式
#引入libopencv_java4.so文件
set_target_properties(lib_opencv
        PROPERTIES
        IMPORTED_LOCATION ${CURRENT_DIR}/src/main/cpp/jniLibs/${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).
        src/main/cpp/native-lib.cpp)

# 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.
        native-lib

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

修改module的gradle文件

apply plugin: 'com.android.application'

android {
    compileSdkVersion 29
    defaultConfig {
        applicationId "com.example.testopencv"
        minSdkVersion 15
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags ""
            }
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"//修改这里
            version "3.10.2"
        }
    }
    sourceSets {//添加这里
        main {
            jni.srcDirs = []
            jniLibs.srcDirs = ['libs']
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test:runner:1.2.0'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
}