Android Studio3.3 加入FFmpeg3.3.9 的一些配置（CMake文件一定要放在project/app目录下！)

我的目录结构：

因为一开始我新建工程时选择了native c++，所以CMake文件是放在cpp目录下的，导致我后来一直报错：’…so’, needed by ‘…so’, missing and no known rule to make it

我的CMake：

# 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.



# 添加ffmpeg头文件路径
include_directories(src/main/cpp/include)

set(CURRENT_DIR ${CMAKE_SOURCE_DIR})
#在Gradle Console输出信息
#CMAKE_SOURCE_DIR: E:/MyApplication2/app
message("CURRENT_DIR:" ${CMAKE_SOURCE_DIR})

add_library( avutil-55
             SHARED
             IMPORTED )
set_target_properties( avutil-55
                       PROPERTIES IMPORTED_LOCATION
                       ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libavutil-55.so)
add_library( swresample-2
             SHARED
             IMPORTED )
set_target_properties( swresample-2
                       PROPERTIES IMPORTED_LOCATION
                       ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libswresample-2.so)
add_library( avfilter-6
             SHARED
             IMPORTED )
set_target_properties( avfilter-6
                       PROPERTIES IMPORTED_LOCATION
                       ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libavfilter-6.so)
add_library( avformat-57
             SHARED
             IMPORTED )
set_target_properties( avformat-57
                       PROPERTIES IMPORTED_LOCATION
                       ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libavformat-57.so)
add_library( swscale-4
             SHARED
             IMPORTED )
set_target_properties( swscale-4
                       PROPERTIES IMPORTED_LOCATION
                       ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libswscale-4.so)
add_library( avcodec-57
             SHARED
             IMPORTED )
set_target_properties( avcodec-57
                       PROPERTIES IMPORTED_LOCATION
                       ${CMAKE_SOURCE_DIR}/src/main/jniLibs/${ANDROID_ABI}/libavcodec-57.so)
add_library( # Sets the name of the library.
             jni-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.
        jni-lib

        avcodec-57
        avfilter-6
        avformat-57
        avutil-55
        swresample-2
        swscale-4
                       # Links the target library to the log library
                       # included in the NDK.
        ${log-lib} )

我的build.gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.ndkdemo5"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags ""
                abiFilters 'armeabi-v7a'
            }
//            ndk {
//                abiFilters 'armeabi-v7a'
//            }
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    sourceSets.main {
        jniLibs.srcDirs = ['src/main/jniLibs']
        jni.srcDirs = []
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}