[Android makes AAR file] #android #gradle #aar

build.gradle

// ...

android {
  // ...
  
  libraryVariants.all { variant ->
        variant.outputs.all { output ->
          variant.assemble.doLast {
            exec {
                    def localProperties = new File(rootDir, "local.properties")
                    Properties properties = new Properties()
                    localProperties.withInputStream { instr ->
                        properties.load(instr)
                    }
                    def sdkDir = properties.getProperty('sdk.dir')
                    def dxCommandPath=sdkDir+'/build-tools/27.0.3/dx.bat'
                    if(Os.isFamily(Os.FAMILY_MAC)){
                        dxCommandPath = sdkDir+'/build-tools/27.0.3/dx'
                    }

                    File dxFile = new File(dxCommandPath)
                    if(!dxFile.exists()) {
                        def buildToolsDir = new File(sdkDir, "build-tools")
                        def buildToolsAvailable = buildToolsDir.list().sort { a, b -> b <=> a }
                        println "Using latest found build tools," + buildToolsAvailable[0]
                        if(Os.isFamily(Os.FAMILY_WINDOWS)){
                            dxCommandPath = sdkDir + '/build-tools/' + buildToolsAvailable[0] + '/dx.bat'
                        }else if(Os.isFamily(Os.FAMILY_MAC)){
                            dxCommandPath = sdkDir + '/build-tools/' + buildToolsAvailable[0] + '/dx'
                        }
                    }
                    println "dx command path="+dxCommandPath
                    commandLine dxCommandPath, '--dex', '--output=build/libs/svrApi.jar', 'build/libs/classes.jar'
            } // end of exec
            
            // copy aar to somewhere
            copy {
              from outputFile
              into 'path_to_folder'
            } // endo of copy
          }
        }
  }
}