以 go get -u go.uber.org/zap为例
提示：
go get go.uber.org/zap: parse ““https://goproxy.cn””: first path segment in URL cannot contain colon

老师在课程里都是https://goproxy.cn，应该没问题，如果改成export GOPROXY=goproxy.cn
之后
go list -m: github.com/stretchr/objx@v0.1.0: Get “https://“goproxy.cn”/github.com/stretchr/objx/@v/v0.1.0.info”: dial tcp: lookup “goproxy.cn”: no such host
go list -m: golang.org/x/sys@v0.0.0-20190412213103-97732733099d: Get “https://“goproxy.cn”/golang.org/x/sys/@v/v0.0.0-20190412213103-97732733099d.info”: dial tcp: lookup “goproxy.cn”: no such host
go list -m: golang.org/x/tools@v0.0.0-20191029190741-b9c20aec41a5: Get “https://“goproxy.cn”/golang.org/x/tools/@v/v0.0.0-20191029190741-b9c20aec41a5.info”: dial tcp: lookup “goproxy.cn”: no such host
go list -m: gopkg.in/yaml.v2@v2.2.2: Get “https://“goproxy.cn”/gopkg.in/yaml.v2/@v/v2.2.2.info”: dial tcp: lookup “goproxy.cn”: no such host

会出现这种信息