windows cannot find package "mime/multipart"

D:\Android\Project\ElinkInvoiceServers\src\home>go run main.go

D:\Go\src\net\http\fs.go:13:2: cannot find package "mime" in any of:

    D:\Go\src\vendor\mime (vendor tree)
    D:\Go\src\mime (from $GOROOT)

D:\Go\src\net\http\fs.go:14:2: cannot find package "mime/multipart" in any of:

    D:\Go\src\vendor\mime\multipart (vendor tree)
    D:\Go\src\mime\multipart (from $GOROOT)

怎么回事 D:\Go\src\net\http\fs.go 是存在的

要安装什么文件吗？