IDE截图：

示例代码来自https://github.com/leancloud/Storage-SDK-Flutter的readme
环境：Windows 10 21H1

flutter doctor -v
[√] Flutter (Channel @u, 2.2.1, on Microsoft Windows [Version 10.0.19042.985], locale zh-CN)
    • Flutter version 2.2.1 at D:\apps\flutter
    • Framework revision 02c026b03c (6 days ago), 2021-05-27 12:24:44 -0700
    • Engine revision 0fdb562ac8
    • Dart version 2.13.1
    • Pub download mirror https://pub.flutter-io.cn
    • Flutter download mirror https://storage.flutter-io.cn

[√] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at D:\apps\Android\Sdk
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = D:\apps\Android\Sdk
    • ANDROID_SDK_ROOT = D:\apps\Android\Sdk
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 11.0.8+10-b944.6842174)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop for Windows (Visual Studio Community 2019 16.10.0)
    • Visual Studio at C:\Program Files (x86)\Microsoft Visual Studio\2019\Community
    • Visual Studio Community 2019 version 16.10.31321.278
    • Windows 10 SDK version 10.0.19041.0

[√] Android Studio
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • android-studio-dir = C:\Program Files\Android\Android Studio
    • Java version OpenJDK Runtime Environment (build 11.0.8+10-b944.6842174)

[√] VS Code, 64-bit edition (version 1.56.2)
    • VS Code at C:\Program Files\Microsoft VS Code
    • Flutter extension version 3.22.0

[√] Proxy Configuration
    • HTTP_PROXY is set
    • NO_PROXY is localhost,127.0.0.1
    • NO_PROXY contains 127.0.0.1
    • NO_PROXY contains localhost

[√] Connected device (3 available)
    • Windows (desktop) • windows • windows-x64    • Microsoft Windows [Version 10.0.19042.985]
    • Chrome (web)      • chrome  • web-javascript • Google Chrome 91.0.4472.77
    • Edge (web)        • edge    • web-javascript • Microsoft Edge 91.0.864.37

• No issues found!

pubspec.yaml

  leancloud_storage:
    git:
      url: https://github.com/leancloud/Storage-SDK-Flutter.git
      ref: flutter2

其余均为AndroidStudio默认

完全摸不着头脑的报错。。。
大佬可否解答一下？

了解了，但是第三行的找不到方法是什么鬼