Golang網頁下載示例

package main

/*

中文編碼問題
*/

import (
    "errors"
    "flag"
    "fmt"
    query "github.com/PuerkitoBio/goquery"
    "golang.org/x/text/encoding/simplifiedchinese"
    "io/ioutil"
    "net/http"
    "os"
    "path/filepath"
    "runtime"
    "strings"
    "sync"
)
var (
    np = runtime.NumCPU()
    _  = runtime.GOMAXPROCS(np)
)
var wg sync.WaitGroup
type Folder struct {
    Url string
    Dir string
}
type File struct {
    Url  string
    Dir  string
    Name string
}
func checkErr(err error) {
    if err != nil {
        fmt.Printf("%v\n", err.Error())
        os.Exit(1)
    }
}
func decodeToGBK(text string) (string, error) {
    dst := make([]byte, len(text)*2)
    tr := simplifiedchinese.GB18030.NewDecoder()
    nDst, _, err := tr.Transform(dst, []byte(text), true)
    if err != nil {
        return text, err
    }
    return string(dst[:nDst]), nil
}
func printEach(index int, item *query.Selection) {
    fmt.Println("Selection: ", item.Text())
}
func isDir(path string) bool {
    return strings.HasSuffix(path, "/")
}
func makeFolder(item query.Selection, url, dir string) (f Folder, err error) {
    tx := item.Text()
    href, ok := item.Attr("href")
    name, err := decodeToGBK(tx)
    if err != nil {
        return
    }
    if !ok {
        err = errors.New("makeFolder : " + tx + " href屬性不存在")
        return
    }
    f = &Folder{Url: url + href, Dir: filepath.Join(dir, name)}
    return
}
func makeFile(item query.Selection, url, dir string) (f File, err error) {
    tx := item.Text()
    href, ok := item.Attr("href")
    if !ok {
        err = errors.New("makeFile : " + tx + " href屬性不存在")
        return
    }
    name, err := decodeToGBK(tx)
    if err != nil {
        return
    }
    f = &File{Url: url + href, Dir: dir, Name: name}
    return
}
func crawl(url, localDir string) {
    doc, err := query.NewDocument(url)
    // checkErr(err)
    if err != nil {
        fmt.Printf("%v\n", err.Error())
        return
    }

items := doc.Find("a")

dir := localDir

if !strings.HasSuffix(url, "/") {
    url += "/"
}

crawlEach := func(i int, item *query.Selection) {
    tx := item.Text()
    if isDir(tx) {
        folder, err := makeFolder(item, url, dir)
        if err != nil {
            fmt.Printf("%v\n", err.Error())
            return
        }
        wg.Add(1)
        go crawlFolder(folder)
    } else {
        file, err := makeFile(item, url, dir)
        if err != nil {
            fmt.Printf("%v\n", err.Error())
            return
        }
        download(file)
    }
}

items.Each(crawlEach)

}
func download(file *File) {
    dir := file.Dir
    url := file.Url
    name := file.Name

if err := os.MkdirAll(dir, os.ModePerm); os.IsExist(err) {
    fmt.Printf("%x is exist\n", dir)
} else {
    os.Chmod(dir, os.ModePerm)
}
resp, err := http.Get(url)
if err != nil {
    fmt.Printf("%v\n", err.Error())
    return
}
defer resp.Body.Close()

body, err := ioutil.ReadAll(resp.Body)
if err != nil {
    fmt.Printf("%v\n", err.Error())
    return
}

fp := string([]rune(filepath.Join(dir, name)))

err = ioutil.WriteFile(fp, body, 0777)
if err != nil {
    fmt.Printf("%v fp:[%v]\n", err.Error(), fp)
    return
}
fmt.Printf("Download: %+v\n", file)

}
func crawlFolder(folder *Folder) {
    url := folder.Url
    dir := folder.Dir

crawl(url, dir)
wg.Done()

}
func main() {
    host := flag.String("host", "http://localhost:8000", "HTTP服務地址Host")
    location := flag.String("locate", "E:/Crawler下載文件", "本地文件系統絕對路徑")
    flag.Parse()
    crawl(host, location)
    wg.Wait()
}</pre>