android studio 3.4 与 opencv-4.1.0-android-sdk

本篇简要5步--展示如何简单调用 opencv

1.创建android工程

 

 

2.拷贝opencv 的 native文件目录

 

 

3.添加 CMakelist.txt

内容：

build.gradle


    externalNativeBuild {

        cmake {

            path file('CMakeLists.txt')

        }

    }



-------------

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.



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.




include_directories(../native/jni/include)  #添加头文件位置

aux_source_directory(src/main/cpp MainCPP)



add_library( # Sets the name of the library.

             test_lib #.so库名 可自定义



             # Sets the library as a shared library.

             SHARED



             # Provides a relative path to your source file(s).

            ${MainCPP} ) #源文件所在目录

# 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.

                       test_lib #.so库名 可自定义

                       # Links the target library to the log library

                       # included in the NDK.

                       ${log-lib} )

 

4.添加cpp目录和内容，java测试类

内容：

test.java

package com.example.myapplication;

public class test {

    static {

        try {

            System.loadLibrary("test_lib");

            System.out.println("load：");



        } catch (Throwable e) {

            System.out.println("err ："+e.toString());

        }

    }

    public static  native String img2gray(String str);
}

--------
com_example_myapplication_test.h


/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_example_myapplication_test */

#ifndef _Included_com_example_myapplication_test
#define _Included_com_example_myapplication_test
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_example_myapplication_test
 * Method:    img2gray
 * Signature: (Ljava/lang/String;)Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_com_example_myapplication_test_img2gray
  (JNIEnv *, jclass, jstring);

#ifdef __cplusplus
}
#endif
#endif



--------
com_example_myapplication_test.cpp

#include "com_example_myapplication_test.h"

#include <opencv2/opencv.hpp>

#include <Android/log.h>
#include <Android/asset_manager.h>
#include <Android/asset_manager_jni.h>

#define TAG "cn.linjk.opencvtest.jni"
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG,TAG ,__VA_ARGS__)
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,TAG ,__VA_ARGS__)
#define LOGW(...) __android_log_print(ANDROID_LOG_WARN,TAG ,__VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,TAG ,__VA_ARGS__)
#define LOGF(...) __android_log_print(ANDROID_LOG_FATAL,TAG ,__VA_ARGS__)

extern "C" {

JNIEXPORT jstring JNICALL Java_com_example_myapplication_test_img2gray
    (JNIEnv *env , jclass objClass, jstring imgFilePath) {

        LOGI("OpenCV version: %s", CV_VERSION);
        return imgFilePath;
    }

}

 

5.调用与测试

 

最后附上参考资料：

Android studio项目中使用JNI调用opencv的c++程序 https://blog.csdn.net/iamqianrenzhan/article/details/83013342
Android平台下OpenCV移植与使用---基于C/C++   https://www.cnblogs.com/linjk/p/6063936.html
--erro   javah -jni   字符错误   --  编码保存为ansi

多目录工程的CmakeLists.txt编写 --https://blog.csdn.net/ktigerhero3/article/details/70313350

windows - AndroidStudio3.4 与 .so    --https://blog.csdn.net/glc22/article/details/90716726