github.com/mattn/go@v0.0.0-20171011075504-07f7db3ea99f/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  	"html/template"
     9  	"io/ioutil"
    10  	"log"
    11  	"net/http"
    12  	"regexp"
    13  )
    14  
    15  type Page struct {
    16  	Title string
    17  	Body  []byte
    18  }
    19  
    20  func (p *Page) save() error {
    21  	filename := p.Title + ".txt"
    22  	return ioutil.WriteFile(filename, p.Body, 0600)
    23  }
    24  
    25  func loadPage(title string) (*Page, error) {
    26  	filename := title + ".txt"
    27  	body, err := ioutil.ReadFile(filename)
    28  	if err != nil {
    29  		return nil, err
    30  	}
    31  	return &Page{Title: title, Body: body}, nil
    32  }
    33  
    34  func viewHandler(w http.ResponseWriter, r *http.Request, title string) {
    35  	p, err := loadPage(title)
    36  	if err != nil {
    37  		http.Redirect(w, r, "/edit/"+title, http.StatusFound)
    38  		return
    39  	}
    40  	renderTemplate(w, "view", p)
    41  }
    42  
    43  func editHandler(w http.ResponseWriter, r *http.Request, title string) {
    44  	p, err := loadPage(title)
    45  	if err != nil {
    46  		p = &Page{Title: title}
    47  	}
    48  	renderTemplate(w, "edit", p)
    49  }
    50  
    51  func saveHandler(w http.ResponseWriter, r *http.Request, title string) {
    52  	body := r.FormValue("body")
    53  	p := &Page{Title: title, Body: []byte(body)}
    54  	err := p.save()
    55  	if err != nil {
    56  		http.Error(w, err.Error(), http.StatusInternalServerError)
    57  		return
    58  	}
    59  	http.Redirect(w, r, "/view/"+title, http.StatusFound)
    60  }
    61  
    62  var templates = template.Must(template.ParseFiles("edit.html", "view.html"))
    63  
    64  func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
    65  	err := templates.ExecuteTemplate(w, tmpl+".html", p)
    66  	if err != nil {
    67  		http.Error(w, err.Error(), http.StatusInternalServerError)
    68  	}
    69  }
    70  
    71  var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$")
    72  
    73  func makeHandler(fn func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc {
    74  	return func(w http.ResponseWriter, r *http.Request) {
    75  		m := validPath.FindStringSubmatch(r.URL.Path)
    76  		if m == nil {
    77  			http.NotFound(w, r)
    78  			return
    79  		}
    80  		fn(w, r, m[2])
    81  	}
    82  }
    83  
    84  func main() {
    85  	http.HandleFunc("/view/", makeHandler(viewHandler))
    86  	http.HandleFunc("/edit/", makeHandler(editHandler))
    87  	http.HandleFunc("/save/", makeHandler(saveHandler))
    88  
    89  	log.Fatal(http.ListenAndServe(":8080", nil))
    90  }