android.applicationVariants.all { variant ->
    variant.outputs.each { output ->
      def outputFile = output.outputFile
      if (outputFile != null && outputFile.name.endsWith('.apk')) {
        //这里修改apk文件名
        def fileName = outputFile.name.replace("app", "你想要的名字")
        output.outputFile = new File(outputFile.parent, fileName)
      }
    }
  }