Android Studio導入Flutter項目、解決舊Flutter項目不支持空安全所出現的一些問題
下載Flutter SDK：https://storage.googleapis.com/dart-archive/channels/stable/release/2.19.3/sdk/dartsdk-windows-x64-release.zip
解壓到你想要放的目錄。配置Flutter SDK的環境變量，配置flutter/bin這個目錄
settings -> marketplace -> plugins -> 搜索Flutter插件 ->安裝Flutter插件，會提示安裝Dart插件，點擊確定都安裝。
Project Sctucture 設置Java的SDK版本為Java 11
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win + R打開cmd -> 運行命令：flutter doctor
提示：
Doctor summary (to see all details, run flutter doctor -v): [√] Flutter (Channel stable, 3.7.6, on Microsoft Windows [版本 10.0.22000.1574], locale zh-CN) [X] Windows Version (Unable to confirm if installed Windows version is 10 or greater) [!] Android toolchain - develop for Android devices (Android SDK version 32.1.0-rc1) X cmdline-tools component is missing Run `path/to/sdkmanager --install "cmdline-tools;latest"` See https://developer.android.com/studio/command-line for more details. X Android license status unknown. Run `flutter doctor --android-licenses` to accept the SDK licenses. See https://flutter.dev/docs/get-started/install/windows#android-setup for more details. [√] Chrome - develop for the web [X] Visual Studio - develop for Windows X Visual Studio not installed; this is necessary for Windows development. Download at https://visualstudio.microsoft.com/downloads/. Please install the "Desktop development with C++" workload, including all of its default components [√] Android Studio (version 2022.1) [√] Connected device (4 available) [√] HTTP Host Availability ! Doctor found issues in 3 categories.
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運行命令：
flutter channel flutter channel master解決：Windows Version (Unable to confirm if installed Windows version is 10 or greater)
打開Android Studio -> Android SDK -> SDK Tools -> 找到cmdline-tools，安裝即可。
解決：cmdline-tools component is missing
flutter doctor --android-licenses
解決：Android license status unknown.
Visual Studio - develop for Windows就不管了，因為用的時Android Studio開發。
Settings -> Flutter -> 配置Flutter SDK的路徑
Settings -> Dart -> 配置Dart SDK路徑，一般配置好Flutter SDK，Dart SDK也會有了。-
導入項目，提示：
'Pub get' has not been run，找到pubspec.yaml，點擊Pub get提示：
The lower bound of "sdk: '>=2.6.0 <3.0.0'" must be 2.12.0 or higher to enable null safety.修改：
environment: sdk: ">=2.12.0 <3.0.0" -
繼續'Pub get'提示：
Because fun_lab depends on json_serializable >=0.1.0+1 <4.1.0 which doesn't support null safety, version solving failed.
修改：
json_annotation: ^4.0.1 json_serializable: ^4.1.2
上面這些提示其實把版本提上去就好了，提到支持空安全的版本就行。
也可以用命令更新：
dart pub upgrade --null-safety
dart pub get
查看Flutter插件庫版本的網站，可以在這里查找插件：
https://pub.dev/
其實高版本的Flutter到這里項目應該就能跑起來了。
一頓操作猛如虎，結果項目太老舊了，用到的很多插件都已經不維護了，沒有支持空安全的版本。沒辦法，只能想其它辦法：
百度搜出來的辦法：
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運行/編譯項目時加參數禁用空安全
flutter run --no-sound-null-safety flutter build --no-sound-null-safety
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修改pubspec.yaml中sdk的版本號
environment: # sdk: ">=2.12.0 <3.0.0" // 2.12支持空安全 sdk: ">=2.11.0 <3.0.0" // 2.11.0不支持
一波操作之后也是不行。
最后：降級flutter版本，下載Flutter1.22.4，因為這個版本的Dart版本是 2.10.4，小于2.12。
降級之后，配置Android SDK環境變量：
ANDROID_HOME：C:\Users\Admin\AppData\Local\Android\Sdk
Path配置
%ANDROID_HOME%\emulator
%ANDROID_HOME%\platform-tools
%ANDROID_HOME%\tools
再使用flutter doctor檢查配置環境，一頓操作，改了一些問題之后項目終跑起來了。
Flutter學習的一些網站：
- Flutter官方文檔：https://flutter.dev/docs
- Flutter中文網：https://flutterchina.club/
- Flutter實戰：https://book.flutterchina.club/
