Android Studio 中无法识别 Flutter 包

Flutter(1.22.5) 包在 Android Studio(Windows-10(64bit)) 中无法识别，即使它们在"C:\src\flutter\packages\flutter\lib"目录中可用。如何解决这个问题？

Flutter 路径 - C:\src\flutter
DartSdk 路径 - C:\src\flutter\bin\cache\dart-sdk

套餐 -

C:\src\flutter>cd "C:\src\flutter\packages\flutter\lib"

C:\src\flutter\packages\flutter\lib>dir
 Volume in drive C has no label.
 Volume Serial Number is 2EAF-73E1

 Directory of C:\src\flutter\packages\flutter\lib

16-Dec-20  04:43 PM    <DIR>          .
16-Dec-20  04:43 PM    <DIR>          ..
16-Dec-20  04:43 PM             3,076 analysis_options_user.yaml
16-Dec-20  04:43 PM             9,707 animation.dart
16-Dec-20  04:43 PM             2,024 cupertino.dart
16-Dec-20  04:43 PM             1,777 foundation.dart
16-Dec-20  04:43 PM             1,216 gestures.dart
16-Dec-20  04:43 PM             6,018 material.dart
16-Dec-20  04:43 PM             2,464 painting.dart
16-Dec-20  04:43 PM               677 physics.dart
16-Dec-20  04:43 PM             3,170 rendering.dart
16-Dec-20  04:43 PM               694 scheduler.dart
16-Dec-20  04:43 PM               707 semantics.dart
16-Dec-20  04:43 PM             1,664 services.dart
16-Dec-20  04:43 PM    <DIR>          src
16-Dec-20  04:43 PM             5,308 widgets.dart
              13 File(s)         38,502 bytes
               3 Dir(s)  27,227,918,336 bytes free

main.dart -

    import 'package:flutter/material.dart';
    import 'C:\src\flutter\packages\flutter\lib\material.dart';

     

错误 -

Error: Could not resolve the package 'flutter' in 'package:flutter/material.dart'.

       ^
lib/main.dart:6:8: Error: Not found: 'package:flutter/material.dart'
import 'package:flutter/material.dart';
       ^
lib/main.dart:7:8: Error: Error when reading 'c:src%0Clutterpackages%0Clutterlibmaterial.dart': StandardFileSystem only supports file:* and data:* URIs
import 'C:\src\flutter\packages\flutter\lib\material.dart';