HTTP host https://maven.google.com/ is not reachable.Reason: An error occurred while checking the HTTP host HTTP host https://cloud.google.com/ is not reachable.Reason: An error occurred while checking the HTTP host
flutter\packages\flutter_tools\lib\src\http_host_validator.dart
将其中的 https://maven.google.com/ 修改为 https://dl.google.com/dl/android/maven2/(解决第一个问题) 再将 kPubDevHttpHost 和 kgCloudHttpHost 两个常量 分别修改为 https://pub.flutter-io.cn/ 和 https://storage.flutter-io.cn/(解决第二个)