看下面两行代码：
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/"))))
注意看下图结果：
- 1、2 行链接地址是带对应前缀的。
- 3行链接地址不带
- 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)
}
})
}
如上图代码所示，
404 是触发了上面的 else 条件。