看下面兩行代碼：
http.Handle("/file/", http.StripPrefix("/file", http.FileServer(http.Dir("./output/"))))
http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("./output/"))))
http.Handle("/file1", http.StripPrefix("/file1", http.FileServer(http.Dir("./output/"))))
http.Handle("/file2", http.StripPrefix("/file2/", http.FileServer(http.Dir("./output/"))))
注意看下圖結果：
- 1、2 行鏈接地址是帶對應前綴的。
- 3行鏈接地址不帶
- 4直接 404
TrimPrefix
TrimPrefix returns s without the provided leading prefix string. If s doesn't start with prefix, s is returned unchanged.
StripPrefix
// StripPrefix returns a handler that serves HTTP requests
// by removing the given prefix from the request URL's Path
// and invoking the handler h. StripPrefix handles a
// request for a path that doesn't begin with prefix by
// replying with an HTTP 404 not found error.
func StripPrefix(prefix string, h Handler) Handler {
if prefix == "" {
return h
}
return HandlerFunc(func(w ResponseWriter, r *Request) {
if p := strings.TrimPrefix(r.URL.Path, prefix); len(p) < len(r.URL.Path) {
r.URL.Path = p
h.ServeHTTP(w, r)
} else {
NotFound(w, r)
}
})
}
如上圖代碼所示，
404 是觸發了上面的 else 條件。