适用于本机库的Android AAR包

Question

我正在寻找一种方法将本机库打包到AAR包中,因此可以通过gradle脚本中的依赖项声明来使用它.

本机库我指的是.cpp文件集或编译的静态库和一组头文件.所以,我的意思是应用程序本身将从本机代码调用库,而不是从Java调用.换句话说,库需要编译应用程序的本机代码.这样就可以轻松管理本机代码的依赖关系.

它甚至可能吗？

到目前为止,我只能找到很多关于如何使用.so文件及其Java接口创建JNI本机库的AAR的问题/示例,因此lib只是一个带有本机实现的Java库,但这不是我需要的.

Answer 1

找到了以下针对该问题的解决方案：

使用Android Experiment Gradle插件版本0.9.1。想法是将库头文件和静态库放入.aar。每种体系结构的标头都放置在其中，ndkLibs/include而静态库则放置在其中ndkLibs/<arch>。然后，在应用程序或依赖于此压缩库的另一个库中，我们仅将ndkLibs目录从AAR 提取到build项目中的目录。请参阅下面的示例gradle文件。

该build.gradle文件与注释库：

apply plugin: "com.android.model.library"

model {
    android {
        compileSdkVersion = 25
        buildToolsVersion = '25.0.2'

        defaultConfig {
            minSdkVersion.apiLevel = 9
            targetSdkVersion.apiLevel = 9
            versionCode = 1
            versionName = '1.0'
        }
        ndk {
            platformVersion = 21
            moduleName = "mylib"
            toolchain = 'clang'
            abiFilters.addAll(['armeabi', 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64', 'mips', 'mips64']) //this is default
            ldLibs.addAll(['android', 'log'])
            stl = 'c++_static'
            cppFlags.add("-std=c++11")
            cppFlags.add("-fexceptions")
            cppFlags.add("-frtti")

            //Add include path to be able to find headers from other AAR libraries
            cppFlags.add("-I" + projectDir.getAbsolutePath() + "/build/ndkLibs/include")
        }

        //For each ABI add link-time library search path to be able to link against other AAR libraries
        abis {
            create("armeabi") {
                ldFlags.add("-L" + projectDir.getAbsolutePath() + "/build/ndkLibs/armeabi")
            }
            create("armeabi-v7a") {
                ldFlags.add("-L" + projectDir.getAbsolutePath() + "/build/ndkLibs/armeabi-v7a")
            }
            create("arm64-v8a") {
                ldFlags.add("-L" + projectDir.getAbsolutePath() + "/build/ndkLibs/arm64-v8a")
            }
            create("x86") {
                ldFlags.add("-L" + projectDir.getAbsolutePath() + "/build/ndkLibs/x86")
            }
            create("x86_64") {
                ldFlags.add("-L" + projectDir.getAbsolutePath() + "/build/ndkLibs/x86_64")
            }
            create("mips") {
                ldFlags.add("-L" + projectDir.getAbsolutePath() + "/build/ndkLibs/mips")
            }
            create("mips64") {
                ldFlags.add("-L" + projectDir.getAbsolutePath() + "/build/ndkLibs/mips64")
            }
        }
    }

    //Configure this library source files
    android.sources {
        main {
            jni {
                //This does not affect AAR packaging
                exportedHeaders {
                    srcDir "../../src/"
                }

                //This tells which source files to compile
                source {
                    srcDirs '../../src'
                }
            }
        }
    }
}

//Custom Maven repository URLs to download AAR files from
repositories {
    maven {
        url 'https://dl.bintray.com/igagis/android/'
    }
}

//Our custom AAR dependencies, those in turn are also packed to AAR using the same approach
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'io.github.igagis:libutki:+'
    compile 'io.github.igagis:libsvgdom:+'
    compile 'org.cairographics:cairo:+'
}


//===================================
//=== Extract NDK files from AARs ===
//This is to automatically extract ndkLibs directory from AAR to build directory before compiling any sources
task extractNDKLibs {
    doLast {
        configurations.compile.each {
            def file = it.absoluteFile
            copy {
                from zipTree(file)
                into "build/"
                include "ndkLibs/**/*"
            }
        }
    }
}
build.dependsOn('extractNDKLibs')
tasks.whenTaskAdded { task ->
    if (task.name.startsWith('compile')) {
        task.dependsOn('extractNDKLibs')
    }
}



//=================================
//=== pack library files to aar ===
//This stuff re-packs the release AAR file adding headers and static libs to there, but removing all shared (.so) libs, as we don't need them. The resulting AAR is put to the project root directory and can be uploaded to Maven along with POM file (you need to write one by hand).

def aarName = name

task copyNdkLibsToAAR(type: Zip) {
    baseName = aarName
    version = "\$(version)"
    extension = 'aar.in'
    destinationDir = file('..') //put resulting AAR file to upper level directory

    from zipTree("build/outputs/aar/" + aarName + "-release.aar")
    exclude('**/*.so') //do not include shared libraries into final AAR
    from("../../src") {
        exclude('makefile')
        exclude('soname.txt')
        exclude('**/*.cpp')
        exclude('**/*.c')
        into('ndkLibs/include')
    }
    from("build/intermediates/binaries/debug/lib"){
        include('**/*.a')
        into('ndkLibs')
    }
}

build.finalizedBy('copyNdkLibsToAAR')

Answer 2

手动破解 gradle 脚本是可行的，但很痛苦且容易出错。

我最近发现了一个插件，可以神奇地将标头捆绑到 AAR 文件中，并在添加依赖项时提取它们并设置构建脚本： https: //github.com/howardpang/androidNativeBundle

关于可重用库：

• 添加导出插件：

  apply plugin: 'com.ydq.android.gradle.native-aar.export'
  

• 定义头文件的位置：

  nativeBundleExport {
      headerDir = "${project.projectDir}/src/main/jni/include"
  }
  

在使用它的模块上：

• 添加导入插件：

  apply plugin: 'com.ydq.android.gradle.native-aar.import'
  

• 添加include ${ANDROID_GRADLE_NATIVE_BUNDLE_PLUGIN_MK}到依赖于它的每个模块Android.mk：

  include $(CLEAR_VARS)
  LOCAL_SRC_FILES := myapp.cpp \
  LOCAL_MODULE := myapp
  LOCAL_LDLIBS += -llog
  include ${ANDROID_GRADLE_NATIVE_BUNDLE_PLUGIN_MK}
  include $(BUILD_SHARED_LIBRARY)