（报错）Flutter Unable to locate Android SDK.

错误提示Flutter Unable to locate Android SDK

[√] Flutter (Channel stable, v1.2.1, on Microsoft Windows [Version 10.0.14393], locale zh-CN)
[X] Android toolchain - develop for Android devices
    X Unable to locate Android SDK.
      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.io/setup/#android-setup for detailed instructions).
      If Android SDK has been installed to a custom location, set ANDROID_HOME to that location.
      You may also want to add it to your PATH environment variable.

解决方案：

(1)报错提示很明显是没有找到本地的 Android sdk，因此，我们需要在电脑上配置环境变量
桌面右键 我的电脑>属性>高级系统设置>环境变量>在用户变量中新建ANDROID_HOME，变量值就是Android SDK路径

设置好之后重启电脑即可

（2）如果方案1不行的话，那么你需要通过cmd命令flutter doctor --android-licenses来执行，一直按y即可

如果你输入flutter doctor --android-licenses报错，就到flutter sdk文件夹下找到flutter_console，点击打开之后在输入flutter doctor --android-licenses

（3） 如果上述方法均无效
我建议你把你配置的Android sdk的配置给删除，然后重新添加，最后记得重启电脑（小编就是方案三得到解决的，亲测有效）