Qt+openCV学习笔记（八）openCV4.5.4+android如何使用动、静态库

前言：

在Android下使用openCV的库，与在其他系统下的原理基本相同，但又有点差异。本次笔记记录下具体的使用方法，供小伙伴们参考

一、使用官方的静态库

静态库使用时，要注意，若库与库之前有相应的依赖，加载的先后顺序不变，若是无法预知需要使用哪些库，可以按照如下的方法测试需要哪些库

1.先放入$$ANDROID_OPENCV/libs/arm64-v8a/libopencv_java4.so在最下面

2.把第三方库放在前面

3.把$$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_core.a放在最前面

4.直接编译程序，等到源码报错时，查看报错的函数是存放于哪个库中，并直接添加到最前面

5.不断重复第4步，直到加入所有需要的库

6.若确认可以正常编译，开如注释掉第三方库，找出程序运行不需要的静态库，最终得到最小的库配置

以arm64-v8a为例，若需要使用二维码识别，最终要加入pro文件的内容如下

unix:!macx{
#添加opencv库（android arm64-v8a版）
contains(ANDROID_TARGET_ARCH,arm64-v8a) {
    message("arm64-v8a")

ANDROID_OPENCV = opencv_dir/opencv4.5.4/OpenCV-android-sdk/sdk/native

    INCLUDEPATH += $$ANDROID_OPENCV/jni/include/opencv2 \
                   $$ANDROID_OPENCV/jni/include

    LIBS += \
        $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_objdetect.a \
        $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_imgproc.a \
        $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_core.a \
        $$ANDROID_OPENCV/3rdparty/libs/arm64-v8a/libcpufeatures.a \
        $$ANDROID_OPENCV/3rdparty/libs/arm64-v8a/libittnotify.a \
        $$ANDROID_OPENCV/3rdparty/libs/arm64-v8a/libquirc.a \
        $$ANDROID_OPENCV/3rdparty/libs/arm64-v8a/libtegra_hal.a \
        $$ANDROID_OPENCV/libs/arm64-v8a/libopencv_java4.so

}
#若不添加，打包时不加入
ANDROID_EXTRA_LIBS = opencv_dir/opencv4.5.4/OpenCV-android-sdk/sdk/native/libs/arm64-v8a/libopencv_java4.so
}

二、使用自行编译的静态库

 自行编译的静态库，同样需要注意有先后顺序。若库与库之前有相应的依赖，加载的先后顺序不变，若是无法预知需要使用哪些库，可以按照如下的方法测试需要哪些库

1.把第三方库放在前面

2.把$$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_core.a放在最前面

3.直接编译程序，等到源码报错时，查看报错的函数是存放于哪个库中，并直接添加到最前面

4.不断重复第4步，直到加入所有需要的库

5.若确认可以正常编译，开如注释掉第三方库，找出程序运行不需要的静态库，最终得到最小的库配置

以arm64-v8a为例，若需要使用微信二维码识别，最终要加入pro文件的内容如下

unix:!macx{
contains(ANDROID_TARGET_ARCH,arm64-v8a) {
    message("arm64-v8a")
ANDROID_OPENCV = opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native

    INCLUDEPATH += $$ANDROID_OPENCV/jni/include/opencv2 \
                   $$ANDROID_OPENCV/jni/include


LIBS += \
    $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_wechat_qrcode.a \
    $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_dnn.a \
    $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_imgproc.a \
    $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_calib3d.a \
    $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_flann.a \
    $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_features2d.a \
    $$ANDROID_OPENCV/staticlibs/arm64-v8a/libopencv_core.a \
    $$ANDROID_OPENCV/3rdparty/libs/arm64-v8a/libcpufeatures.a \
    $$ANDROID_OPENCV/3rdparty/libs/arm64-v8a/libittnotify.a \
    $$ANDROID_OPENCV/3rdparty/libs/arm64-v8a/libquirc.a \
    $$ANDROID_OPENCV/3rdparty/libs/arm64-v8a/libtegra_hal.a
}

三、使用自行编译的动态库

动态库无加载顺序，直接加入即可，但要注意加入ANDROID_EXTRA_LIBS中，否则打包时不会加入

直接编译程序，等到源码报错时，查看报错的函数是存放于哪个库中，并直接添加即可

以arm64-v8a为例，若需要使用微信二维码识别，最终要加入pro文件的内容如下

unix:!macx{
contains(ANDROID_TARGET_ARCH,arm64-v8a) {
    message("arm64-v8a")
ANDROID_OPENCV = opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native

    INCLUDEPATH += $$ANDROID_OPENCV/jni/include/opencv2 \
                   $$ANDROID_OPENCV/jni/include


LIBS += \
    $$ANDROID_OPENCV/libs/arm64-v8a/libopencv_wechat_qrcode.so \
    $$ANDROID_OPENCV/libs/arm64-v8a/libopencv_dnn.so \
    $$ANDROID_OPENCV/libs/arm64-v8a/libopencv_imgproc.so \
    $$ANDROID_OPENCV/libs/arm64-v8a/libopencv_calib3d.so \
    $$ANDROID_OPENCV/libs/arm64-v8a/libopencv_flann.so \
    $$ANDROID_OPENCV/libs/arm64-v8a/libopencv_features2d.so \
    $$ANDROID_OPENCV/libs/arm64-v8a/libopencv_core.so

ANDROID_EXTRA_LIBS = \
    opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native/libs/arm64-v8a/libopencv_core.so \
    opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native/libs/arm64-v8a/libopencv_features2d.so \
    opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native/libs/arm64-v8a/libopencv_flann.so \
    opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native/libs/arm64-v8a/libopencv_calib3d.so \
    opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native/libs/arm64-v8a/libopencv_imgproc.so \
    opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native/libs/arm64-v8a/libopencv_dnn.so \
    opencv_dir/opencv4.5.4/build_android_arm64-v8a/install/sdk/native/libs/arm64-v8a/libopencv_wechat_qrcode.so

}

后记：

在编译时，不勾选world，各个库要分散成多个文件，虽然可以减少打包后的程序体积，但不利于初学者学习

建议初学者，在编译时勾选world，以降低学习难度