运行flutter run出现错误：No supported devices connected
在通过flutter run启动项目的过程中，遇到提示No supported devices connected的错误，错误的意思为没有找到连接的设备
解决方案
- 运行
flutter doctor，查看设备情况
flutter doctor
- 运行
flutter emulators，查看可连接设备
flutter emulators
- 运行
flutter emulators --launch <emulator id>，连接到指定设备，此时会打开一个模拟器
// mac端
flutter emulators --launch iOS Simulator
// windows
flutter emulators --launch Pixel_3a_API_30_x86
- 运行
flutter run，启动项目，正常运行
flutter run
