go - 防止为所有不匹配的请求调用 http.handleFunc ("/", func(w, r) { }) 处理程序

Question

考虑下面非常基本的 HTTP 服务器代码，通过使用参数调用 run() 在 main() 函数中启动，其中参数旨在指定一个根目录路径。

package main

import "fmt"
import "net/http"
import "strings"

func main() {
    // run("/")              // option 1
    // run("/newbase")       // option 2
}

func run(basePath string) {
    var path = fmt.Sprintf("%s", basePath)
    if !strings.HasPrefix(path, "/") {
        path = fmt.Sprintf("/%s", path)
    }
    if !strings.HasSuffix(path, "/") {
        path = fmt.Sprintf("%s/", path)
    }

    http.HandleFunc(fmt.Sprintf("%sfoo", path), handleFoo)
    http.HandleFunc(fmt.Sprintf("%sbar", path), handleBar)
    http.HandleFunc(fmt.Sprintf("%s", path), handleRoot)

    http.ListenAndServe(":60001", nil)
}

func handleRoot(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "Root")
}
func handleFoo(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "Foo")
}
func handleBar(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "Bar")
}

如果调用 run("/")，服务器应响应 URL /、/foo 和 /酒吧。

如果调用 run("/newbase")，服务器应响应 URL /newbase/、/newbase/foo和/newbase/bar。

我希望任何其他 URL 返回标准 HTTP/404，但似乎为未处理的子路径调用了 / 处理程序。这会导致行为上出现奇怪的差异:

                  | For run("/")                    | For run("/newbase")
Entered URL       |---------------------------------+---------------------------------
                  | Desired        | Actual         | Desired        | Actual
------------------+----------------+----------------+----------------+----------------
 /                | HTTP/200 Root  | HTTP/200 Root  | HTTP/404       | HTTP/404
------------------+----------------+----------------+----------------+----------------
 /foo             | HTTP/200 Foo   | HTTP/200 Foo   | HTTP/404       | HTTP/404
------------------+----------------+----------------+----------------+----------------
 /foo/qux         | HTTP/404       | HTTP/200 Root  | HTTP/404       | HTTP/404
------------------+----------------+----------------+----------------+----------------
 /bar             | HTTP/200 Bar   | HTTP/200 Bar   | HTTP/404       | HTTP/404
------------------+----------------+----------------+----------------+----------------
 /baz             | HTTP/404       | HTTP/200 Root  | HTTP/404       | HTTP/404
------------------+----------------+----------------+----------------+----------------
 /newbase         | HTTP/404       | HTTP/200 Root  | HTTP/200 Root  | HTTP/200 Root
------------------+----------------+----------------+----------------+----------------
 /newbase/foo     | HTTP/404       | HTTP/200 Root  | HTTP/200 Foo   | HTTP/200 Foo
------------------+----------------+----------------+----------------+----------------
 /newbase/foo/qux | HTTP/404       | HTTP/200 Root  | HTTP/404       | HTTP/200 Root
------------------+----------------+----------------+----------------+----------------
 /newbase/bar     | HTTP/404       | HTTP/200 Root  | HTTP/200 Bar   | HTTP/200 Bar
------------------+----------------+----------------+----------------+----------------
 /newbase/baz     | HTTP/404       | HTTP/200 Root  | HTTP/404       | HTTP/200 Root

我认为发生这种情况是因为 http.HandleFunc 的第一个参数被视为最接近匹配的模式，而不是精确匹配。

是否有任何方法可以强制处理程序要求精确(最好不区分大小写)匹配，以便它不会为未注册 URL 的 / 处理程序提供服务，而是使用默认 HTTP 进行响应/404？

# go version
go version go1.14.9 linux/amd64

Answer 1

http.ServeMux documentation说:

Patterns name fixed, rooted paths, like "/favicon.ico", or rooted subtrees, like "/images/" (note the trailing slash).

和

Note that since a pattern ending in a slash names a rooted subtree, the pattern "/" matches all paths not matched by other registered patterns, not just the URL with Path == "/".

要处理 /(或以 / 结尾的任何其他模式)上的精确匹配，请将代码添加到处理程序，以便在路径不等于时响应 404模式。使用http.NotFound以“默认”404 响应进行响应。

http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    if r.URL.Path != "/" {
        http.NotFound(w, r)
        return
    }
    // code to handle / here
})