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 := 0; 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) - 1:]
        if (flags & ListDir) == 0 {
            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", 0)
    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