go language reads json and downloads hd girl pictures

I have learned golang for one day. I wrote go while looking at the document and I read and analyzed json and downloaded the picture
json api is the love wallpaper HD mac 1920x1200 version, hd sister image

Conclusion: go + json = shit

package main
import (
  "fmt"
  "io"
  "io/ioutil"
  "net/http"
  "os"
  "path/filepath"
  "strconv"
  //"encoding/json"
  "strings"
  "github.com/bitly/go-simplejson"
)
const (
  DataRoot   = "./tmp/" //  The root directory where the cover image is stored 
  TimeoutLimit = 10    //  Set timeout time 
  PageUrl   = "http://api.lovebizhi.com/macos_v4.php?a=category&spdy=1&tid=3&order=hot&color_id=3&device=105&uuid=436e4ddc389027ba3aef863a27f6e6f9&mode=0&retina=0&client_id=1008&device_id=31547324&model_id=105&size_id=0&channel_id=70001&screen_width=1920&screen_height=1200&bizhi_width=1920&bizhi_height=1200&version_code=19&language=zh-Hans&jailbreak=0&mac=&p={pid}"
)
//  Wallpaper type, numbered, long, wide and URL
type Wallpaper struct {
  Pid   int
  Url   string
  Width  int
  Height  int
}
//  Download and save the image locally 
func SaveImage(paper *Wallpaper) {
  res, err := http.Get(paper.Url)
  defer res.Body.Close()
  if err != nil {
    fmt.Printf("%d HTTP ERROR:%s", paper.Pid, err)
    return
  }
  // Save the image in the resolution directory 
  Dirname := DataRoot + strconv.Itoa(paper.Width) + "x" + strconv.Itoa(paper.Height) + "/"
  if ! isDirExist(Dirname) {
    os.Mkdir(Dirname, 0755);
    fmt.Printf("dir %s created\n", Dirname)
  }
  // According to the URL File name creation file 
  filename := filepath.Base(paper.Url)
  dst, err := os.Create(Dirname + filename)
  if err != nil {
    fmt.Println("%d HTTP ERROR:%s", paper.Pid, err)
    return
  }
  //  Written to the file 
  io.Copy(dst, res.Body)
}
func isDirExist(path string) bool {
  p, err := os.Stat(path)
  if err != nil {
    return os.IsExist(err)
  } else {
    return p.IsDir()
  }
}
func main() {
  // Check and create a temporary directory 
  if ! isDirExist(DataRoot) {
    os.Mkdir(DataRoot, 0755);
    fmt.Println("dir %s created", DataRoot)
  }
  // generate 1 Data sequence, used to get pagination 
  pow := make([]int, 2)
  for i := range pow {
    if (i > 0) {
      url := strings.Replace(PageUrl, "{pid}", strconv.Itoa(i), -1);
      fmt.Println(i, url);
      response, err := http.Get(url)
      if( err != nil) {
        fmt.Println(err)
        continue
      }
      body, _ := ioutil.ReadAll(response.Body)
      js, err := simplejson.NewJson(body)
      // traverse data All the data below 
      data := js.Get("data").MustArray()
      for _, v := range data {
        v := v.(map[string]interface{})
        for kk, vv := range v {
          if(kk == "file_id") {
            // Here,  vv  is 1 a []interface{} json.Number I don't know how to get the value out, but I'm using a silly one, right Sprintf
            vv := fmt.Sprintf("%s", vv)
            imgid,_ := strconv.Atoi(vv)
            url := fmt.Sprintf("http://s.qdcdn.com/c/%d,1920,1200.jpg", imgid)
            fmt.Println(kk, imgid, url);
            paper := &Wallpaper{imgid, url, 1920, 1200}
            SaveImage(paper);
          }
        }
      }
    }
  }
  fmt.Println("oh yes, all job done.")
}

That's all for this article, I hope you enjoy it.