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| 1 | +// Copyright 2023 The Go Authors. All rights reserved. |
| 2 | +// Use of this source code is governed by a BSD-style |
| 3 | +// license that can be found in the LICENSE file. |
| 4 | + |
| 5 | +// Hello is a simple hello, world demonstration web server. |
| 6 | +// |
| 7 | +// It serves version information on /version and answers |
| 8 | +// any other request like /name by saying "Hello, name!". |
| 9 | +// |
| 10 | +// See golang.org/x/example/outyet for a more sophisticated server. |
| 11 | +package main |
| 12 | + |
| 13 | +import ( |
| 14 | + "flag" |
| 15 | + "fmt" |
| 16 | + "html" |
| 17 | + "log" |
| 18 | + "net/http" |
| 19 | + "os" |
| 20 | + "runtime/debug" |
| 21 | + "strings" |
| 22 | +) |
| 23 | + |
| 24 | +func usage() { |
| 25 | + fmt.Fprintf(os.Stderr, "usage: helloserver [options]\n") |
| 26 | + flag.PrintDefaults() |
| 27 | + os.Exit(2) |
| 28 | +} |
| 29 | + |
| 30 | +var ( |
| 31 | + greeting = flag.String("g", "Hello", "Greet with `greeting`") |
| 32 | + addr = flag.String("addr", "localhost:8080", "address to serve") |
| 33 | +) |
| 34 | + |
| 35 | +func main() { |
| 36 | + // Parse flags. |
| 37 | + flag.Usage = usage |
| 38 | + flag.Parse() |
| 39 | + |
| 40 | + // Parse and validate arguments (none). |
| 41 | + args := flag.Args() |
| 42 | + if len(args) != 0 { |
| 43 | + usage() |
| 44 | + } |
| 45 | + |
| 46 | + // Register handlers. |
| 47 | + // All requests not otherwise mapped with go to greet. |
| 48 | + // /version is mapped specifically to version. |
| 49 | + http.HandleFunc("/", greet) |
| 50 | + http.HandleFunc("/version", version) |
| 51 | + |
| 52 | + log.Printf("serving http://%s\n", *addr) |
| 53 | + log.Fatal(http.ListenAndServe(*addr, nil)) |
| 54 | +} |
| 55 | + |
| 56 | +func version(w http.ResponseWriter, r *http.Request) { |
| 57 | + info, ok := debug.ReadBuildInfo() |
| 58 | + if !ok { |
| 59 | + http.Error(w, "no build information available", 500) |
| 60 | + return |
| 61 | + } |
| 62 | + |
| 63 | + fmt.Fprintf(w, "<!DOCTYPE html>\n<pre>\n") |
| 64 | + fmt.Fprintf(w, "%s\n", html.EscapeString(info.String())) |
| 65 | +} |
| 66 | + |
| 67 | +func greet(w http.ResponseWriter, r *http.Request) { |
| 68 | + name := strings.Trim(r.URL.Path, "/") |
| 69 | + if name == "" { |
| 70 | + name = "Gopher" |
| 71 | + } |
| 72 | + |
| 73 | + fmt.Fprintf(w, "<!DOCTYPE html>\n") |
| 74 | + fmt.Fprintf(w, "Hello, %s!\n", html.EscapeString(name)) |
| 75 | +} |
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