| // Copyright 2023 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Hello is a simple hello, world demonstration web server. |
| // |
| // It serves version information on /version and answers |
| // any other request like /name by saying "Hello, name!". |
| // |
| // See golang.org/x/example/outyet for a more sophisticated server. |
| package main |
| |
| import ( |
| "flag" |
| "fmt" |
| "html" |
| "log" |
| "net/http" |
| "os" |
| "runtime/debug" |
| "strings" |
| ) |
| |
| func usage() { |
| fmt.Fprintf(os.Stderr, "usage: helloserver [options]\n") |
| flag.PrintDefaults() |
| os.Exit(2) |
| } |
| |
| var ( |
| greeting = flag.String("g", "Hello", "Greet with `greeting`") |
| addr = flag.String("addr", "localhost:8080", "address to serve") |
| ) |
| |
| func main() { |
| // Parse flags. |
| flag.Usage = usage |
| flag.Parse() |
| |
| // Parse and validate arguments (none). |
| args := flag.Args() |
| if len(args) != 0 { |
| usage() |
| } |
| |
| // Register handlers. |
| // All requests not otherwise mapped with go to greet. |
| // /version is mapped specifically to version. |
| http.HandleFunc("/", greet) |
| http.HandleFunc("/version", version) |
| |
| log.Printf("serving http://%s\n", *addr) |
| log.Fatal(http.ListenAndServe(*addr, nil)) |
| } |
| |
| func version(w http.ResponseWriter, r *http.Request) { |
| info, ok := debug.ReadBuildInfo() |
| if !ok { |
| http.Error(w, "no build information available", 500) |
| return |
| } |
| |
| fmt.Fprintf(w, "<!DOCTYPE html>\n<pre>\n") |
| fmt.Fprintf(w, "%s\n", html.EscapeString(info.String())) |
| } |
| |
| func greet(w http.ResponseWriter, r *http.Request) { |
| name := strings.Trim(r.URL.Path, "/") |
| if name == "" { |
| name = "Gopher" |
| } |
| |
| fmt.Fprintf(w, "<!DOCTYPE html>\n") |
| fmt.Fprintf(w, "%s, %s!\n", *greeting, html.EscapeString(name)) |
| } |
