如何告诉Gradle不要在我的.jar依赖项中排除.so文件？

Question

I have a .jar dependency which comes with .so library inside it.

library.jar
       |
       -----com/company
              |
              -----.class files
       -----libs
              |
              -----libX.so

The jar makes use of this .so library internally, and I'm building an Android app that makes use of the jar.

Everything is good until after I build the apk : by exploring it using 7zip, I discover that the .so files have disappeared, leading to all sorts of errors when using the app.

So is there any way to tell Gradle not to exclude the .so files when building? I don't want to copy them manually into a folder in my Android Project, since I'm not using them directly, but the .jar library is the one loading them.

Edit 1 : Adding build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.company.myapp"
        minSdkVersion 24
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:design:28.0.0'
    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'
    implementation files('libs/lib1.jar')
    implementation files('libs/lib2.jar')
}

Edit 2 : Here is the solution following the previous suggestions of @shizhen

1- My .jar included the .so files in libs directory. I had to rename that to lib .

2- I unpacked the .jar to gather the .so files.

3- I created src/jniLibs folder and put the .so files, each in its respective <ANDROID_ABI> folder.

4- I modified the build.gradle file to include :

android {
...
sourceSets {
        main {
            jni.srcDirs = []
            jniLibs.srcDir 'src/jniLibs'
        }
    }
}

5 - Et voila! The final .apk now includes the native libraries.

Answer 1

Everything is good until after I build the apk : by exploring it using 7zip, I discover that the .so files have disappeared, leading to all sorts of errors when using the app.

I believe your jar dependency was not originally for android but generally for Java.

Android app uses .dex format, so all your .jar dependencies will be repackaged into one or more dex files. You .so files won't be used as it is inside the jar.

So is there any way to tell Gradle not to exclude the .so files when building? I don't want to copy them manually into a folder in my Android Project, since I'm not using them directly, but the .jar library is the one loading them.

So, in order to adapt your jar to Android app, you HAVE TO unzip the jar taking out all the .so files and manually put them into src/jniLibs/<ANDROID_ABI>/ , eg

jniLibs
    ├── arm64-v8a
    │   ├── libxxx.so
    │   └── libyyy.so
    ├── armeabi-v7a
    │   ├── libxxx.so
    │   └── libyyy.so
    ├── x86
    │   ├── libxxx.so
    │   └── libyyy.so
    └── x86_64
        ├── libxxx.so
        └── libyyy.so

Answer 2

Just a guess based on the Android docs on “Shrink your code and resources” : it seems that ProGuard is automatically used for release builds, in order to remove apparently unused code. You could try to disable that:

// …
    buildTypes {
        release {
            minifyEnabled false
            useProguard false
        }
    }
// …

If that helps, then ProGuard would be your culprit. Instead of leaving it disabled, you could then try to explicitly tell it to keep the files that must not be removed.

Answer 3

Simply set your sourceSets in build.gradle(Module: app)

android {
   ...
   ...
sourceSets {
    main {
        jniLibs.srcDirs = [
                './src/main/jniLibs'
        ]
    }
 }
}

Use ndk if your project requried:

defaultConfig {
    ...
    ndk {
        abiFilters "armeabi-v7a", "x86"
    }
}