github.com/riscv/riscv-go@v0.0.0-20200123204226-124ebd6fcc8e/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  	"net/http"
    11  	"regexp"
    12  )
    13  
    14  type Page struct {
    15  	Title string
    16  	Body  []byte
    17  }
    18  
    19  func (p *Page) save() error {
    20  	filename := p.Title + ".txt"
    21  	return ioutil.WriteFile(filename, p.Body, 0600)
    22  }
    23  
    24  func loadPage(title string) (*Page, error) {
    25  	filename := title + ".txt"
    26  	body, err := ioutil.ReadFile(filename)
    27  	if err != nil {
    28  		return nil, err
    29  	}
    30  	return &Page{Title: title, Body: body}, nil
    31  }
    32  
    33  func viewHandler(w http.ResponseWriter, r *http.Request, title string) {
    34  	p, err := loadPage(title)
    35  	if err != nil {
    36  		http.Redirect(w, r, "/edit/"+title, http.StatusFound)
    37  		return
    38  	}
    39  	renderTemplate(w, "view", p)
    40  }
    41  
    42  func editHandler(w http.ResponseWriter, r *http.Request, title string) {
    43  	p, err := loadPage(title)
    44  	if err != nil {
    45  		p = &Page{Title: title}
    46  	}
    47  	renderTemplate(w, "edit", p)
    48  }
    49  
    50  func saveHandler(w http.ResponseWriter, r *http.Request, title string) {
    51  	body := r.FormValue("body")
    52  	p := &Page{Title: title, Body: []byte(body)}
    53  	err := p.save()
    54  	if err != nil {
    55  		http.Error(w, err.Error(), http.StatusInternalServerError)
    56  		return
    57  	}
    58  	http.Redirect(w, r, "/view/"+title, http.StatusFound)
    59  }
    60  
    61  var templates = template.Must(template.ParseFiles("edit.html", "view.html"))
    62  
    63  func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
    64  	err := templates.ExecuteTemplate(w, tmpl+".html", p)
    65  	if err != nil {
    66  		http.Error(w, err.Error(), http.StatusInternalServerError)
    67  	}
    68  }
    69  
    70  var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$")
    71  
    72  func makeHandler(fn func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc {
    73  	return func(w http.ResponseWriter, r *http.Request) {
    74  		m := validPath.FindStringSubmatch(r.URL.Path)
    75  		if m == nil {
    76  			http.NotFound(w, r)
    77  			return
    78  		}
    79  		fn(w, r, m[2])
    80  	}
    81  }
    82  
    83  func main() {
    84  	http.HandleFunc("/view/", makeHandler(viewHandler))
    85  	http.HandleFunc("/edit/", makeHandler(editHandler))
    86  	http.HandleFunc("/save/", makeHandler(saveHandler))
    87  
    88  	http.ListenAndServe(":8080", nil)
    89  }