Flutter-Notes｜FlutterApk-大小优化探索

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追赶，摸索，永不停歇～

前言

还记得刚入坑 Flutter 打包时，被深深震惊了一番，卧槽，这包好大！

  • ✓ Built build/app/outputs/apk/release/app-release.apk (23.8MB).

足足将近 24 MB，第一反馈真的懵逼了。

当然间接提交市场后，也是被人各种 diss，起因还是没什么性能，包贼大，用户下载贼不难受。

强烈要求优化 Apk 大小。

既然是摸索，前提我还是个刚入 Flutter 坑的小白白，所以嘛，不免不全面，欢送各位大佬拍砖、指导～

摸索之路 一部曲

首先，我首次打包的形式如下：

雷同应用上面的命令（默认带有 –release）：

  • flutter build apk

一、熊猫压缩法（缩小 0.7 MB）

首先第一想法，图片我没做压缩，同样通过查看后，发现图片在 apk 占比为 4.1%：

  • 2.3 % Flutter 援用到的资源文件；
  • 1.8% Android 启动页的背景图。

最初，咱们通过国宝之手试试最初能缩小多少？

这里别离针对 Flutter 下图片资源、Android/iOS 启动页进行压缩。

再次运行 build apk 后，实现输入如下日志：

  • ✓ Built build/app/outputs/apk/release/app-release.apk (23.1MB).

再来看 Apk 中图片的占比以及升高到 1%：

最终 Apk 大小间接缩小了 0.7 MB，还是比拟爽的。

二、so 优化大法（缩小 14 MB）

做 Android 的小伙伴晓得，对于咱们这些小厂没能力搞动静下发 so 的小渣渣而言，只能默默逆向大厂 Apk，看看人家是怎么做的，而后借（抄）鉴（袭）。

针对 Flutter 打出的 Apk 包，排在第一位的便是 lib，占比 86.4%，足足有 19.6 MB：

这里看到将咱们编写的 Dart 代码转化为不同架构下的 so 库，以供原生调用（我是这么猜想的哈）。

针对不同 CPU 架构所代表含意，尤其 Flutter 打包 Apk 生成的三种 CPU 架构别离对应什么含意：

  • x86_64： Intel 64 位，个别用于平板或者模拟器，反对 x86 以及 x86_64 CPU 架构设施。
  • arm64-v8a： 第 8 代 64 位，蕴含 AArch32、AArch64 两个执行状态，且对应 32、64 bit，并且反对 armeabi、armeabi-v7a 以及 arm64-v8a。
  • armeabi-v7a： 第 7 代 arm v7，应用硬件浮点运算，具备高级拓展性能，兼容 armeabi 以及 armeabi-v7a，而且目前大部分手机都是这个架构。

其实咱们第一次通过 flutter build apk 命令生成 apk 时，Google 这里曾经为咱们提醒了：

 heliquan@Mac  ~/CodePro/FlutterPro/xxx_app master ● flutter build apk
You are building a fat APK that includes binaries for android-arm, android-arm64, android-x64.
If you are deploying the app to the Play Store, it's recommended to use app bundles or split the APK to reduce the APK size.
    To generate an app bundle, run:
        flutter build appbundle --target-platform android-arm,android-arm64,android-x64
        Learn more on: https://developer.android.com/guide/app-bundle
    To split the APKs per ABI, run:
        flutter build apk --target-platform android-arm,android-arm64,android-x64 --split-per-abi
        Learn more on:  https://developer.android.com/studio/build/configure-apk-splits#configure-abi-split                                        
Running Gradle task 'assembleRelease'...                                
Running Gradle task 'assembleRelease'... Done                      13.8s
✓ Built build/app/outputs/apk/release/app-release.apk (23.1MB).

接下来通过以下命令进行别离打包（构建指定 CPU 架构类型 Apk 包）：

  • flutter build apk –target-platform android-arm,android-arm64,android-x64 –split-per-abi

这里解释下这个命令的含意：

  • 首先 flutter build apk 示意以后构建 release 包；
  • 前面 android-arm,android-arm64,android-x64 则是指定生成对应架构的 release 包；
  • 最初的 –split-per-abi 则示意告知须要依照咱们指定的类型别离打包，如果移除则间接构建蕴含所有 CPU 架构的 Apk 包。

所以这个命令的含意就是通知编译器，我须要你为我针对我指定的三种不同架构别离生成对应的 Apk 包。

有的小伙伴就说了，你这空口无凭，没证据啊。

好，我给你运行一波～

  • 验证：flutter build apk –target-platform android-arm,android-arm64,android-x64 后果 
 heliquan@Mac  ~/CodePro/FlutterPro/xxx_app   master ●  flutter build apk --target-platform android-arm,android-arm64,android-x64                
You are building a fat APK that includes binaries for android-arm, android-arm64, android-x64.
If you are deploying the app to the Play Store, it's recommended to use app bundles or split the APK to reduce the APK size.
    To generate an app bundle, run:
        flutter build appbundle --target-platform android-arm,android-arm64,android-x64
        Learn more on: https://developer.android.com/guide/app-bundle
    To split the APKs per ABI, run:
        flutter build apk --target-platform android-arm,android-arm64,android-x64 --split-per-abi
        Learn more on:  https://developer.android.com/studio/build/configure-apk-splits#configure-abi-split                                        
Removed unused resources: Binary resource data reduced from 817KB to 815KB: Removed 0%
Running Gradle task 'assembleRelease'...                                
Running Gradle task 'assembleRelease'... Done                     115.8s
✓ Built build/app/outputs/apk/release/app-release.apk (23.1MB).

看见没，事实论证后果。

最初，咱们采取告知编译器为咱们生成指定 CPU 架构的 Apk 的形式，并查看对应输入日志信息：

 heliquan@Mac  ~/CodePro/FlutterPro/xxx_app   master ●  flutter build apk --target-platform android-arm,android-arm64,android-x64 --split-per-abi                                         
Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%
Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%
Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%
Running Gradle task 'assembleRelease'...                                
Running Gradle task 'assembleRelease'... Done                      36.0s
✓ Built build/app/outputs/apk/release/app-armeabi-v7a-release.apk (9.8MB).
✓ Built build/app/outputs/apk/release/app-arm64-v8a-release.apk (10.1MB).
✓ Built build/app/outputs/apk/release/app-x86_64-release.apk (10.2MB).

看看 app-armeabi-v7a-release.apk 包大小，后果是不是贼喜人？由 23.8 MB 间接缩小到 9.8 MB。

随后咱们看下对应的 apk 内容：

lib 占比也从原来的 86.4%，19.6 MB 间接缩小为 67.2%，大小 6.3 MB。

三、混同大法好（缩小 0.4 MB）

还记得 Android 混同的魅力吗？

  • 减少逆向难度；
  • 缩小 Apk 大小；
  • 。。。

对此 Flutter 也为咱们提供了混同命令：

  • flutter build apk –obfuscate –split-debug-info=/<project-name>/<directory>

简略说下我集体对于此命令的了解：

  • –obfuscate：开启混同操作；
  • –split-debug-info=：将因混同生成的 map 符号表缓存到此地位。

这里咱们先测试下，间接构建完整包，并增加混同操作，输入的 apk 大小有多少：

 heliquan@Mac  ~/CodePro/FlutterPro/xxx_app   master ●  flutter build apk --obfuscate --split-debug-info=HLQ_Struggle
You are building a fat APK that includes binaries for android-arm, android-arm64, android-x64.
If you are deploying the app to the Play Store, it's recommended to use app bundles or split the APK to reduce the APK size.
    To generate an app bundle, run:
        flutter build appbundle --target-platform android-arm,android-arm64,android-x64
        Learn more on: https://developer.android.com/guide/app-bundle
    To split the APKs per ABI, run:
        flutter build apk --target-platform android-arm,android-arm64,android-x64 --split-per-abi
        Learn more on:  https://developer.android.com/studio/build/configure-apk-splits#configure-abi-split                                        
Running Gradle task 'assembleRelease'...                                
Running Gradle task 'assembleRelease'... Done                      60.3s
✓ Built build/app/outputs/apk/release/app-release.apk (21.9MB).

同样也在我的项目根目录下生成了符号文件：

相比一开始的 23.8 MB，缩小了 1.9 MB。那么咱们间接针对不同 CPU 生成对应的 Apk 并增加混同后果又是怎么呢？

➜  xxx_app git:(master) ✗ flutter build apk --obfuscate --split-debug-info=debugInfo  --target-platform android-arm,android-arm64,android-x64 --split-per-abi                                       
Running Gradle task 'assembleRelease'...                                
Running Gradle task 'assembleRelease'... Done                      39.3s
✓ Built build/app/outputs/apk/release/app-armeabi-v7a-release.apk (9.4MB).
✓ Built build/app/outputs/apk/release/app-arm64-v8a-release.apk (9.7MB).
✓ Built build/app/outputs/apk/release/app-x86_64-release.apk (9.8MB).

未混同的 v7a 大小与开启混同相比，开启混同缩小了 0.4 MB。

还不错。

对于混同的文件，出问题怎么调试呢？

莫慌，Flutter 同样提供了 symbolize 神器，当然这个不在涉猎范畴内，就不具体解释了，晓得就好：

heliquan@Mac  ~/CodePro/FlutterPro/haozhuan_app   master ●  flutter symbolize -h
Symbolize a stack trace from an AOT compiled flutter application.

Usage: flutter symbolize [arguments]
-h, --help                                                                     Print this usage information.
-d, --debug-info=</out/android/app.arm64.symbols>                              A path to the symbols file generated with "--split-debug-info".
-i, --input=</crashes/stack_trace.err>                                         A file path containing a Dart stack trace.
-o, --output=<A file path for a symbolicated stack trace to be written to.>    

Run "flutter help" to see global options.

End

下面叨叨半天，总结一个比拟有用的命令：

  • flutter build apk –obfuscate –split-debug-info=HLQ_Struggle –target-platform android-arm,android-arm64,android-x64 –split-per-abi

含意就是，哥，帮我针对不同 CPU 架构别离打包，别忘记混同哈，生成的符号表文件记得帮我放在 HLQ_Struggle 目录下。

具体日志如下：

 heliquan@Mac  ~/CodePro/FlutterPro/xxx_app   master ●   flutter build apk --obfuscate --split-debug-info=HLQ_Struggle --target-platform android-arm,android-arm64,android-x64 --split-per-abi                                          
Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%
Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%
Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%
Running Gradle task 'assembleRelease'...                                
Running Gradle task 'assembleRelease'... Done                      36.9s
✓ Built build/app/outputs/apk/release/app-armeabi-v7a-release.apk (9.4MB).
✓ Built build/app/outputs/apk/release/app-arm64-v8a-release.apk (9.7MB).
✓ Built build/app/outputs/apk/release/app-x86_64-release.apk (9.8MB).

当然也有小伙伴说了，打包前 clean 下，生成的包会小，理论测试一下：

 heliquan@Mac  ~/CodePro/FlutterPro/xxx_app   master ●  flutter clean           
Cleaning Xcode workspace...                                         3.3s
Deleting build...                                                2,774ms (!)
Deleting .dart_tool...                                              41ms
Deleting Generated.xcconfig...                                       0ms
Deleting flutter_export_environment.sh...                            0ms
Deleting App.framework...                                            9ms
 heliquan@Mac  ~/CodePro/FlutterPro/xxx_app   master ●   flutter build apk --obfuscate --split-debug-info=HLQ_Struggle --target-platform android-arm,android-arm64,android-x64 --split-per-abi                                          
Running Gradle task 'assembleRelease'...                                                                                                                                                  Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%                             
Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%                             
Removed unused resources: Binary resource data reduced from 816KB to 814KB: Removed 0%                             
Running Gradle task 'assembleRelease'...                                                                           
Running Gradle task 'assembleRelease'... Done                     215.3s (!)
✓ Built build/app/outputs/apk/release/app-armeabi-v7a-release.apk (9.4MB).
✓ Built build/app/outputs/apk/release/app-arm64-v8a-release.apk (9.7MB).
✓ Built build/app/outputs/apk/release/app-x86_64-release.apk (9.8MB).

依据以上输入后果，并没发现缩小了哪儿。

一点小经验分享，当然必定会有更好的操作方法，然而目前仅次于此，欢送各位大佬交换～

Thanks

  • 熊猫压缩法
  • Flutter apk 最简略的瘦身形式
  • Android ABI
  • Build an APK
  • 混同 Dart 代码
  • 测量你的利用体积
  • Flutter apps are too big in size
  • Build and release an Android app
  • How to decrease the size of app.framework on iOS? #21813：看得我各种懵

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flutter
发表至： flutter
2020-07-10
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