github.com/hbdrawn/golang@v0.0.0-20141214014649-6b835209aba2/doc/articles/wiki/final.go (about)

     1  // Copyright 2010 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  package main
     6  
     7  import (
     8  	"flag"
     9  	"html/template"
    10  	"io/ioutil"
    11  	"log"
    12  	"net"
    13  	"net/http"
    14  	"regexp"
    15  )
    16  
    17  var (
    18  	addr = flag.Bool("addr", false, "find open address and print to final-port.txt")
    19  )
    20  
    21  type Page struct {
    22  	Title string
    23  	Body  []byte
    24  }
    25  
    26  func (p *Page) save() error {
    27  	filename := p.Title + ".txt"
    28  	return ioutil.WriteFile(filename, p.Body, 0600)
    29  }
    30  
    31  func loadPage(title string) (*Page, error) {
    32  	filename := title + ".txt"
    33  	body, err := ioutil.ReadFile(filename)
    34  	if err != nil {
    35  		return nil, err
    36  	}
    37  	return &Page{Title: title, Body: body}, nil
    38  }
    39  
    40  func viewHandler(w http.ResponseWriter, r *http.Request, title string) {
    41  	p, err := loadPage(title)
    42  	if err != nil {
    43  		http.Redirect(w, r, "/edit/"+title, http.StatusFound)
    44  		return
    45  	}
    46  	renderTemplate(w, "view", p)
    47  }
    48  
    49  func editHandler(w http.ResponseWriter, r *http.Request, title string) {
    50  	p, err := loadPage(title)
    51  	if err != nil {
    52  		p = &Page{Title: title}
    53  	}
    54  	renderTemplate(w, "edit", p)
    55  }
    56  
    57  func saveHandler(w http.ResponseWriter, r *http.Request, title string) {
    58  	body := r.FormValue("body")
    59  	p := &Page{Title: title, Body: []byte(body)}
    60  	err := p.save()
    61  	if err != nil {
    62  		http.Error(w, err.Error(), http.StatusInternalServerError)
    63  		return
    64  	}
    65  	http.Redirect(w, r, "/view/"+title, http.StatusFound)
    66  }
    67  
    68  var templates = template.Must(template.ParseFiles("edit.html", "view.html"))
    69  
    70  func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
    71  	err := templates.ExecuteTemplate(w, tmpl+".html", p)
    72  	if err != nil {
    73  		http.Error(w, err.Error(), http.StatusInternalServerError)
    74  	}
    75  }
    76  
    77  var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$")
    78  
    79  func makeHandler(fn func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc {
    80  	return func(w http.ResponseWriter, r *http.Request) {
    81  		m := validPath.FindStringSubmatch(r.URL.Path)
    82  		if m == nil {
    83  			http.NotFound(w, r)
    84  			return
    85  		}
    86  		fn(w, r, m[2])
    87  	}
    88  }
    89  
    90  func main() {
    91  	flag.Parse()
    92  	http.HandleFunc("/view/", makeHandler(viewHandler))
    93  	http.HandleFunc("/edit/", makeHandler(editHandler))
    94  	http.HandleFunc("/save/", makeHandler(saveHandler))
    95  
    96  	if *addr {
    97  		l, err := net.Listen("tcp", "127.0.0.1:0")
    98  		if err != nil {
    99  			log.Fatal(err)
   100  		}
   101  		err = ioutil.WriteFile("final-port.txt", []byte(l.Addr().String()), 0644)
   102  		if err != nil {
   103  			log.Fatal(err)
   104  		}
   105  		s := &http.Server{}
   106  		s.Serve(l)
   107  		return
   108  	}
   109  
   110  	http.ListenAndServe(":8080", nil)
   111  }