Go语言练习：网络编程实例——简易图片上传网站

1、代码结构

2、运行实例

---

1、代码结构

$ tree
.
├── photoweb.go
├── public
│   ├── css
│   ├── images
│   └── js
├── uploads
└── views
    ├── list.html
    └── upload.html

　　1.1）photoweb.go

 package main

 import (
     "io"
     "os"
     "log"
     "net/http"
     "io/ioutil"
     "html/template"
     "path"
     //"debug"
     "fmt"
 )

 const (
     UPLOAD_DIR = "./uploads"
     TEMPLATE_DIR = "./views"
     ListDir = 0x0001
 )

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

 func init() {
     fileInfoArr, err := ioutil.ReadDir(TEMPLATE_DIR)
     check(err)

     var templateName, templatePath string
     for _, fileInfo := range fileInfoArr {
         templateName = fileInfo.Name()
         if ext := path.Ext(templateName); ext != ".html" {
             continue
         }
         templatePath = TEMPLATE_DIR + "/" + templateName;
         t := template.Must(template.ParseFiles(templatePath))
         rlname := realName(templateName)
         log.Println("Loading template:", rlname)
         templates[rlname] = t
     }
 }

 func realName(str string) string {
     str = path.Base(str)
     if str == "" {
         return str
     }
     for i := ; i < len(str); i++ {
         if '.' == str[i] {
             return str[:i]
         }
     }
     return str
 }

 func uploadHandler(w http.ResponseWriter, r * http.Request) {
     if r.Method == "GET" {
         readerHtml(w, "upload", nil);
     }

     if r.Method == "POST" {
         f, h , err := r.FormFile("image")
         if err != nil {
             http.Error(w, err.Error(),
             http.StatusInternalServerError)
             return
         }
         filename := h.Filename
         defer f.Close()
         t, err := os.Create(UPLOAD_DIR + "/" + filename)
         if err != nil {
             http.Error(w, err.Error(),
             http.StatusInternalServerError)
             return
         }
         defer t.Close()
         if _, err := io.Copy(t, f); err != nil {
             http.Error(w, err.Error(),
             http.StatusInternalServerError)
             return
         }
         http.Redirect(w, r, "/view?id="+filename,
         http.StatusFound)
     }
 }

 func viewHandler(w http.ResponseWriter, r * http.Request) {
     imageId        := r.FormValue("id")
     imagePath    := UPLOAD_DIR + "/" + imageId
     if exists := isExists(imagePath); !exists {
         http.NotFound(w, r)
         return
     }
     w.Header().Set("Content-Type", "image")
     http.ServeFile(w, r, imagePath)
 }

 func isExists(path string) bool {
     _, err := os.Stat(path)
     if err == nil {
         return true
     }
     return os.IsExist(err)
 }

 func listHandler(w http.ResponseWriter, r * http.Request) {
     fileInfoArr, err := ioutil.ReadDir("./uploads")
     if err != nil {
         http.Error(w, err.Error(),
         http.StatusInternalServerError)
         fmt.Println("faild @ listHandler")
         return
     }

     locals := make(map[string]interface{})
     images := []string{}
     for _, fileInfo := range fileInfoArr {
         if fileInfo.Name() != ".svn" {
             images = append(images, fileInfo.Name())
         }
     }
     locals["images"] = images

     readerHtml(w, "list", locals);
 }

 func readerHtml(w http.ResponseWriter, tmpl string, locals map[string]interface{}){
     err := templates[tmpl].Execute(w, locals)
     check(err)
 }

 func check(err error) {
     if err != nil {
         panic(err)
     }
 }

 func safeHandler(fn http.HandlerFunc) http.HandlerFunc {
     return func(w http.ResponseWriter, r * http.Request) {
         defer func() {
             if e , ok := recover().(error); ok {
                 http.Error(w, e.Error(), http.StatusInternalServerError)
                 log.Println("WARN: panic in %v - %v", fn, e)
 //                log.Println(string(debug.Stack()))
             }
         }()
         fn(w, r)
     }
 }

 func staticDirHandler(mux * http.ServeMux, prefix string, staticDir string, flags int) {
     mux.HandleFunc(prefix, func(w http.ResponseWriter, r * http.Request) {
         file := staticDir + r.URL.Path[len(prefix) - :]
         if (flags & ListDir) ==  {
             if exists := isExists(file); !exists {
                 http.NotFound(w, r)
                 fmt.Println(file, "not found")
                 return
             }
         }
         fmt.Println("handle static dir")
         http.ServeFile(w, r, file)
     })
 }

 func main() {
     mux := http.NewServeMux()
     staticDirHandler(mux, "/assets/", "./public", )
     mux.HandleFunc("/", safeHandler(listHandler))
     mux.HandleFunc("/view", safeHandler(viewHandler))
     mux.HandleFunc("/upload", safeHandler(uploadHandler))
     err := http.ListenAndServe(":8090", mux)
     if err != nil {
         log.Fatal("ListenAndServe: ", err.Error())
     }
 }

　　1.2）views/list.html

 <!doctype html>
 <html>
     <head>
         <meta charset="utf-8">
         <title>List</title>
     </head>
     <body>
         <ol>
             {{range $.images}}
             <li><a href="/view?id={{.|urlquery}}">{{.|html}}</a></li>
             {{end}}
         </ol>
     </body>
 </html>

　　1.3）views/upload.html

 <!doctype html>
 <html>
     <head>
         <meta charset="utf-8">
         <title>Upload</title>
     </head>
     <body>
         <form method="POST" action="/upload" enctype="multipart/form-data">
             Choose an image to upload: <input name="image" type="file" />
             <input type="submit" value="Upload" />
         </form>
     </body>
 </html>

2、运行及结果

　　2.1）运行

$ go run photoweb.go
2015/07/25 02:15:24 Loading template: list
2015/07/25 02:15:24 Loading template: upload

　　2.2）在浏览器端输入服务器地址