I am trying to build a library(sdk/aar) which uses native code within library. But I am getting error like ‘java.lang.UnsatisfiedLinkError: No implementation found’ for my native functions declared in library class.
package com.abc.android.count_ai
class CountActivity : BaseActivity(), CameraBridgeViewBase.CvCameraViewListener2 {
//these functions is in red color and showing wrong package name to resolve
//Cannot resolve corresponding JNI function
//Java_com_abc_android_count_1ai_CountActivity_detection.
private external fun detection(img: Long, cPath: String, wPath:
String, frameInfo: CFrameInfo)
private external fun isBlurry(img: Long, threshold: Double): Boolean
}
//BaseActivity where
package com.abc.android.count_ai;
import android.os.Bundle;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
public class BaseActivity extends AppCompatActivity {
static {
System.loadLibrary("native-lib");
}
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
}
>native-lib.cpp
#include <jni.h>
#include <android/log.h>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
#include <fstream>
#include <algorithm>
#include <string>
#import <opencv2/opencv.hpp>
#import <opencv2/dnn/dnn.hpp>
#include <android/asset_manager.h>
#define TAG "NativeLib"
using namespace std;
using namespace cv;
extern "C" {
void JNIEXPORT Java_com_abc_android_count_ai_CountActivity_detection(JNIEnv *env, jobject instance,
jlong imgAddr, jstring cPath, jstring wPath, jobject frameInfo) {
}
jboolean JNICALL Java_com_abc_android_count_ai_CountActivity_isBlurry(JNIEnv *env, jobject instance, jlong imgAddr, jdouble blurThreshold) {
}
}
App works file if I put all library code into main module. But if I put cpp code and android code into a library project and call its class from main module’s MainActivity the it give me above error. Project is building fine but This error comes when I try to call those native methods into library project.
Means cpp is not working in case of library module and I have to distribute those functions as a SDK.
build.gradle(:count_ai)
Commented code has been tried.
plugins {
id 'com.android.library'
id 'kotlin-android'
}
android {
compileSdk 31
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'
}
defaultConfig {
minSdk 21
targetSdk 31
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
externalNativeBuild {
cmake {
cppFlags "-frtti -fexceptions"
abiFilters 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64'
arguments "-DOpenCV_DIR=" + opencvsdk + "/sdk/native"
}
}
}
/*sourceSets {
main {
// The libs directory contains prebuilt libraries that are used by the
// app's library defined in CMakeLists.txt via an IMPORTED target.
jniLibs.srcDirs = [opencvsdk + '/sdk/native/libs']
}
}*/
/*externalNativeBuild {
cmake {
path "src/main/cpp/CMakeLists.txt"
version "3.10.2"
}
}*/
/*sourceSets {
main {
jniLibs.srcDirs = [opencvsdk + '/sdk/native/libs']
java.srcDirs = [project.projectDir.toString() + '/src']
aidl.srcDirs = [project.projectDir.toString() + '/src']
res.srcDirs = [project.projectDir.toString() + '/src/main/res']
manifest.srcFile project.projectDir.toString() + '/src/main/AndroidManifest.xml'
}
}*/
println 'ProjectDir in contours:'+project.projectDir.toString()
externalNativeBuild {
cmake {
path (project.projectDir.toString() + '/src/main/cpp/CMakeLists.txt')
version "3.10.2"
}
}
}
dependencies {
implementation 'androidx.core:core-ktx:1.8.0'
implementation 'androidx.appcompat:appcompat:1.4.2'
implementation project(':opencv')
}
CMakeLists.txt
cmake_minimum_required(VERSION 3.4.1)
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(
native-lib
SHARED
native-lib.cpp)
find_library(
log-lib
log )
target_link_libraries( # Specifies the target library.
native-lib
lib_opencv
# Links the target library to the log library
# included in the NDK.
${log-lib} )