golang 引入外部包时报cannot refer to unexported

1.报错信息

# command-line-arguments
./test.go:7:2: cannot refer to unexported name api.demo

2.工程目录

.
├── api
│?? └── apis.go
├── go.mod
└── test.go

1 directory, 3 files

apis.go:

package api
func Demo(){
	println("###########")
}

test.go:

package main
import (
	api "test/api"
)

func main(){
	api.demo()
}

3.原因：模块中到处的函数首字母必须为大写

将apis.go文件改为：

package main
import (
	api "test/api"
)

func main(){
	api.Demo()
}