如何在 Golang 中制作绝对路径 HTTP 重定向

Question

我正在阅读源代码goto，我在goto/talk/0/main.go中找到了下面的代码：

http.Redirect(w, r, url, http.StatusFound)

根据上下文，url是绝对路径，并且预期绝对路径重定向。但正如golang/http/redirect所提到的：

Redirect通过重定向到 URL 来回复请求，该 URL 可能是相对于请求路径的路径。

它的结果是相对路径重定向。我不知道http.Redirect以前是否做过绝对路径重定向，但现在没有。

那么如何在 golang 中进行绝对路径重定向呢？我在网上搜索，但一无所获，有人能帮我吗？提前谢谢。

Answer 1

当你去 golang 文档进行http.Redirect时，你实际上可以点击蓝色的标题：

函数重定向

它将带您进入不言自明的源代码列表：

// Redirect replies to the request with a redirect to url,
// which may be a path relative to the request path.
func Redirect(w ResponseWriter, r *Request, urlStr string, code int) {
    if u, err := url.Parse(urlStr); err == nil {
        // If url was relative, make absolute by
        // combining with request path.
        // The browser would probably do this for us,
        // but doing it ourselves is more reliable.
        // NOTE(rsc): RFC 2616 says that the Location
        // line must be an absolute URI, like
        // "http://www.google.com/redirect/",
        // not a path like "/redirect/".
        // Unfortunately, we don't know what to
        // put in the host name section to get the
        // client to connect to us again, so we can't
        // know the right absolute URI to send back.
        // Because of this problem, no one pays attention
        // to the RFC; they all send back just a new path.
        // So do we.
        oldpath := r.URL.Path
        if oldpath == "" { // should not happen, but avoid a crash if it does
            oldpath = "/"
        }
        if u.Scheme == "" {
            // no leading http://server
            if urlStr == "" || urlStr[0] != '/' {
                // make relative path absolute
                olddir, _ := path.Split(oldpath)
                urlStr = olddir + urlStr
            }
            var query string
            if i := strings.Index(urlStr, "?"); i != -1 {
                urlStr, query = urlStr[:i], urlStr[i:]
            }
            // clean up but preserve trailing slash
            trailing := strings.HasSuffix(urlStr, "/")
            urlStr = path.Clean(urlStr)
            if trailing && !strings.HasSuffix(urlStr, "/") {
                urlStr += "/"
            }
            urlStr += query
        }
    }
    w.Header().Set("Location", urlStr)
    w.WriteHeader(code)
    // RFC2616 recommends that a short note "SHOULD" be included in the
    // response because older user agents may not understand 301/307.
    // Shouldn't send the response for POST or HEAD; that leaves GET.
    if r.Method == "GET" {
        note := "<a href="" + htmlEscape(urlStr) + "">" + statusText[code] +
                "</a>.n"
        fmt.Fprintln(w, note)
    }
}

此技巧也适用于其他功能。

Answer 2

我终于发现要执行绝对路径重定向，url必须是完整的网址，例如http://www.stackoverflow.com或https://github.com，而不是www.stackoverflow.com。