我是高朗的新手。有人可以解釋一下“Readdir”和“Open”包裝器方法是如何工作的嗎？這個例子來自 Golang 文檔。 https://pkg.go.dev/net/http#example-FileServer-DotFileHiding更具體地說，在“Readdir”方法中，該語句files, err := f.File.Readdir(n)具有 n 個 int 值，但它是從哪里傳遞的以及它是如何工作的。程序中的任何地方都沒有調(diào)用“Readdir”方法。同樣在“打開”包裝器中file, err := fsys.FileSystem.Open(name)package mainimport (    "io/fs"    "log"    "net/http"    "strings")// containsDotFile reports whether name contains a path element starting with a period.// The name is assumed to be a delimited by forward slashes, as guaranteed// by thehttp.FileSystem interface.func containsDotFile(name string) bool {    parts := strings.Split(name, "/")    for _, part := range parts {        if strings.HasPrefix(part, ".") {            return true        }    }    return false}// dotFileHidingFile is the http.File use in dotFileHidingFileSystem.// It is used to wrap the Readdir method of http.File so that we can// remove files and directories that start with a period from its output.type dotFileHidingFile struct {    http.File}f// Readdir is a wrapper around the Readdir method of the embedded File// that filters out all files that start with a period in their name.func (f dotFileHidingFile) Readdir(n int) (fis []fs.FileInfo, err error) {    files, err := f.File.Readdir(n)    for _, file := range files { // Filters out the dot files        if !strings.HasPrefix(file.Name(), ".") {            fis = append(fis, file)        }    }    return}// dotFileHidingFileSystem is an http.FileSystem that hides// hidden "dot files" from being served.type dotFileHidingFileSystem struct {    http.FileSystem}// Open is a wrapper around the Open method of the embedded FileSystem// that serves a 403 permission error when name has a file or directory// with whose name starts with a period in its path.func (fsys dotFileHidingFileSystem) Open(name string) (http.File, error) {    if containsDotFile(name) { // If dot file, return 403 response        return nil, fs.ErrPermission    }