Flutter报错Got socket error trying to find package flutter_custom_clippers at https://pub.dartlang.org

问题描述：

Got socket error trying to find package coverage at http://pub.dartlang.org

Error: Unable to pub upgrade flutter tool. Retrying in five seconds...

大致意思是连接https://pub.dartlang.org配置dart包失败

访问flutter官方，仔细查看flutter的配置方法，发现如下图所示Note，相信有很多朋友配置环境的时候都没有注意该Note。

接下来查看该note内容：

If you’re installing or using Flutter in China, it may be helpful to use a trustworthy local mirror site that hosts Flutter’s dependencies. 
To instruct the Flutter tool to use an alternate storage location, 
you will need to set two environment variables, PUB_HOSTED_URL and FLUTTER_STORAGE_BASE_URL, before running the flutter command.

解释一下：大致意思是，如果在中国安装flutter，配置国内镜像是很好的解决办法。 到此，解决方法找到。

配置本地环境方法

对于 Linux 和 MacOS 来说，添加如下两条环境变量即可：

 export PUB_HOSTED_URL=https://pub.flutter-io.cn 
 export FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn

对于Window

系统变量创建两个

name: PUB_HOSTED_URL; 
value: https://pub.flutter-io.cn


name: FLUTTER_STORAGE_BASE_URL; 
value: https://storage.flutter-io.cn