Go语言写Web 应用程序

package main

import (
    "fmt"
    "io/ioutil"
    "os"
)

这fmt,ioutil和os都是go语言的标准库，一会我将增加其他方法和更多的包。

数据结构

让我们声明一个数据结构，这个结构主要包含两个字段，一个是标题，一个是内容。

type Page struct {
    Title    string
    Body    []byte
}

接下来，我们给Page 这个结构体写个保存方法，代码如下：

func (p *Page) save() os.Error {
    filename := p.Title + ".txt"
    return ioutil.WriteFile(filename, p.Body, 0600)
}

这个方法的签名是:接收一个Page结构体指针，返回一个os.Error错误。

在一下的代码中还是用了http包和模板包，具体内容参考具体代码，再这里就不详细贴出来了。下面是模板内容，把他们放到wiki.go同一目录下。

<h1>Editing {{.Title |html}}</h1>

<form action="/save/{{.Title |html}}" method="POST">
<div><textarea name="body" rows="20" cols="80">{{printf "%s" .Body |html}}</textarea></div>
<div><input type="submit" value="Save"></div>
</form>

<h1>{{.Title |html}}</h1>

<p>[<a href="/edit/{{.Title |html}}">edit</a>]</p>

<div>{{printf "%s" .Body |html}}</div>

package main

import (
    "http"
    "io/ioutil"
    "os"
    "regexp"
    "template"
)

type Page struct {
    Title string
    Body  []byte
}

func (p *Page) save() os.Error {
    filename := p.Title + ".txt"
    return ioutil.WriteFile(filename, p.Body, 0600)
}

func loadPage(title string) (*Page, os.Error) {
    filename := title + ".txt"
    body, err := ioutil.ReadFile(filename)
    if err != nil {
        return nil, err
    }
    return &Page{Title: title, Body: body}, nil
}

func viewHandler(w http.ResponseWriter, r *http.Request, title string) {
    p, err := loadPage(title)
    if err != nil {
        http.Redirect(w, r, "/edit/"+title, http.StatusFound)
        return
    }
    renderTemplate(w, "view", p)
}

func editHandler(w http.ResponseWriter, r *http.Request, title string) {
    p, err := loadPage(title)
    if err != nil {
        p = &Page{Title: title}
    }
    renderTemplate(w, "edit", p)
}

func saveHandler(w http.ResponseWriter, r *http.Request, title string) {
    body := r.FormValue("body")
    p := &Page{Title: title, Body: []byte(body)}
    err := p.save()
    if err != nil {
        http.Error(w, err.String(), http.StatusInternalServerError)
        return
    }
    http.Redirect(w, r, "/view/"+title, http.StatusFound)
}

var templates = make(map[string]*template.Template)

func init() {
    for _, tmpl := range []string{"edit", "view"} {
        t := template.Must(template.ParseFile(tmpl + ".html"))
        templates[tmpl] = t
    }
}

func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
    err := templates[tmpl].Execute(w, p)
    if err != nil {
        http.Error(w, err.String(), http.StatusInternalServerError)
    }
}

const lenPath = len("/view/")

var titleValidator = regexp.MustCompile("^[a-zA-Z0-9]+$")

func makeHandler(fn func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        title := r.URL.Path[lenPath:]
        if !titleValidator.MatchString(title) {
            http.NotFound(w, r)
            return
        }
        fn(w, r, title)
    }
}

func main() {
    http.HandleFunc("/view/", makeHandler(viewHandler))
    http.HandleFunc("/edit/", makeHandler(editHandler))
    http.HandleFunc("/save/", makeHandler(saveHandler))
    http.ListenAndServe(":8080", nil)
}

$ 8g wiki.go
$ 8l wiki.8
$ ./8.out

在地址栏输入地址：http://localhost:8080/view/aNewPage