Flutter 存量Android接入Flutter躺坑指南
有思想，也有忧伤和理想，这才是生活。
人生没有如果，只有后果和结果。
前言
最近给一个老项目接入Flutter，遇到了一些问题，记录下。
存量Android接入Flutter官方文档：Integrate a Flutter module into your Android project
踩坑的本机环境
注意对比下我的环境和你的环境是否一样，有些问题在Flutter的新版本中已经被修复了。
- Flutter环境安装教程：起步:安装Flutter
➜ app git:(master) ✗ flutter --version
Flutter 1.9.1+hotfix.6 • channel stable • https://github.com/flutter/flutter.git
Framework • revision cc949a8e8b (3 weeks ago) • 2019-09-27 15:04:59 -0700
Engine • revision b863200c37
Tools • Dart 2.5.0
Flutter doctor -v
➜ app git:(master) ✗ flutter doctor -v
[✓] Flutter (Channel stable, v1.9.1+hotfix.4, on Mac OS X 10.15 19A583, locale en-CN)
• Flutter version 1.9.1+hotfix.4 at /Users/.../flutter
• Framework revision cc949a8e8b (3 weeks ago), 2019-09-27 15:04:59 -0700
• Engine revision b863200c37
• Dart version 2.5.0
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
• Android SDK at /Users/notzuonotdied/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-29, build-tools 29.0.2
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 11.1)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 11.1, Build version 11A1027
• CocoaPods version 1.8.3
[✓] Android Studio (version 3.5)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 40.1.2
• Dart plugin version 191.8423
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b49-5587405)
[!] IntelliJ IDEA Ultimate Edition (version 2019.2.3)
• IntelliJ at /Applications/IntelliJ IDEA.app
✗ Flutter plugin not installed; this adds Flutter specific functionality.
✗ Dart plugin not installed; this adds Dart specific functionality.
• For information about installing plugins, see
https://flutter.dev/intellij-setup/#installing-the-plugins
[✓] VS Code (version 1.39.2)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.5.1
[✓] Connected device (1 available)
• iPhone 11 Pro Max • 61AA9D21-B994-4FC5-9164-757EABF90190 • ios • com.apple.CoreSimulator.SimRuntime.iOS-13-1 (simulator)
! Doctor found issues in 1 category.
错误
升级JDK1.8
项目中接入了Tinker，且JDK版本为1.7。
接入Flutter需要升级项目JDK版本为1.8。
Java 8 language support, as requested by 'android.enableD8.desugaring= true' in your gradle.properties file, is not supported when 'android.useDexArchive= false'.
需要在项目根目录下的gradle.properties中增加以下的代码：
android.useDexArchive = true
# Java8语法脱糖
android.enableD8.desugaring = true
- 最新版本不支持java 8了吗 #67，介绍了解决方法。
- Java 8 language support, as requested by ‘android.enableD8.desugaring= true’ in your gradle.properties file, is not supported when ‘android.useDexArchive= false’.
混淆带来的问题
Warning: io.flutter.embedding.android.FlutterView: can't find referenced method 'android.graphics.Insets getSystemGestureInsets()' in library class android.view.WindowInsets
Warning: io.flutter.embedding.android.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.embedding.android.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.embedding.android.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.embedding.android.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.embedding.android.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.embedding.android.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.view.FlutterView: can't find referenced method 'android.graphics.Insets getSystemGestureInsets()' in library class android.view.WindowInsets
Warning: io.flutter.view.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.view.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.view.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.view.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.view.FlutterView: can't find referenced class android.graphics.Insets
Warning: io.flutter.view.FlutterView: can't find referenced class android.graphics.Insets
在proguard中增加-dontwarn android.**即可解决。
- Proguard error after upgrating stable to v1.9.1+hotfix.2 #40168
- After upgrading to 1.9 duplicate class and reference warnings throw error when building apk #40364
minSdkVersion
有些老项目支持到了14，所以需要做下处理。
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="包名">
<uses-sdk tools:overrideLibrary="com.example.xxx" />
manifest>
- uses-sdk:minSdkVersion 15 cannot be smaller than version 16 declared in library
- Manifest merger failed : uses-sdk:minSdkVersion 14 cannot be smaller than version 16 declared in lib…
- Manifest merger failed : uses-sdk:minSdkVersion 14 cannot be smaller than version 16 declared in library
EnclosingMember annotations
问题：Android studio warning - InnerClass annotations are missing corresponding EnclosingMember annotations
增加如下内容：
-keepattributes *Annotation*
-keep @**annotation** class * {*;}
附录
D8相关
- Android Studio 3.0+ 新Dex编译器D8 Desugar R8
- Error:Java 8 language support, as requested by ‘android.enableD8.desugaring= true’
- 最新版本不支持java 8了吗 #67，介绍了解决方法。
- Java 8 language support, as requested by ‘android.enableD8.desugaring= true’ in your gradle.properties file, is not supported when ‘android.useDexArchive= false’.
- The option ‘android.useDexArchive’ is deprecated and should not be used anymore. #290