如何解决Flutter中‘Dart library 'dart:ui' is not available on this platform’错误？

问题描述 #

我是Flutter新手，已经安装了Dart和Flutter，在Android Studio和VS Code里装了相关插件。创建第一个Flutter项目后用Android Studio打开，没改任何代码就启动，出现大量Error: Dart library 'dart:ui' is not available on this platform.错误，完整报错信息如下：

/D:/Flutter/flutter/packages/flutter/lib/src/material/animated_icons.dart:9:8: Error: Dart library 'dart:ui' is not available on this platform.
import 'dart:ui' as ui show Canvas, Paint, Path;
       ^
Context: The unavailable library 'dart:ui' is imported through these packages:

    package:prova => package:flutter => dart:ui
    ...

Detailed import paths for (some of) the these imports:

    package:prova/main.dart => package:flutter/material.dart => package:flutter/src/material/about.dart => package:flutter/foundation.dart => package:flutter/src/foundation/assertions.dart => package:flutter/src/foundation/diagnostics.dart => package:flutter/src/foundation/debug.dart => dart:ui
    ...（省略其余路径）

/D:/Flutter/flutter/packages/flutter/lib/src/material/animated_icons.dart:10:8: Error: Dart library 'dart:ui' is not available on this platform.
import 'dart:ui' show lerpDouble;
       ^
/D:/Flutter/flutter/packages/flutter/lib/src/material/app.dart:5:8: Error: Dart library 'dart:ui' is not available on this platform.
import 'dart:ui' as ui;
       ^
...（省略其余重复错误）

Process finished with exit code 254

试过在Android Studio里配置Flutter和Dart路径，但没用。怀疑是Flutter装在非默认目录，是不是要改环境变量？

解决方法 #

1. 配置系统环境变量 #

dart:ui是Flutter专属的底层库，只有在Flutter运行环境下才会加载，必须确保Flutter的bin目录在系统PATH里：

• 打开系统环境变量设置，在PATH中添加D:/Flutter/flutter/bin
• 配置完成后，重启所有终端和IDE，打开终端输入flutter doctor，确保没有报错，能正常检测到Flutter和相关组件

2. 用正确的方式运行项目 #

• 不要用Dart的运行按钮，Android Studio里要选带有Flutter图标的运行按钮（绿色箭头旁边的下拉框，确认是Flutter运行配置）
• 如果用终端运行，执行flutter run，不要用dart run命令，纯Dart环境不支持dart:ui

3. 重新检查IDE的SDK配置 #

• 打开Android Studio的File > Settings > Languages & Frameworks > Flutter，确认Flutter SDK路径是D:/Flutter/flutter，Dart SDK会自动关联到Flutter自带的版本（路径一般是D:/Flutter/flutter/bin/cache/dart-sdk）
• 清理IDE缓存：File > Invalidate Caches...，选择Invalidate and Restart，彻底重启IDE

4. 重新初始化项目 #

如果以上方法都没用，尝试用命令行创建新项目：

flutter create my_new_flutter_app

然后用Android Studio打开这个新创建的项目，再尝试启动

内容的提问来源于stack exchange，提问作者Marco