go语言实现抓取高清图片

package main
import (
    "io/ioutil"
    "log"
    "net/http"
    "os"
    "regexp"
    "strconv"
    "strings"
    "sync"
)
var urlist [4]string
var album chan string
var w sync.WaitGroup
var dir string
func main() {
    dir = "tmp/"
    err := os.Mkdir(dir, 0777)
    if err != nil {
        isexist := os.IsExist(err)
        log.Println(isexist)
    }
    album = make(chan string, 200)
    urlist = [4]string{"http://me2-sex.lofter.com/tag/%E7%BE%8E%E5%A5%B3%E6%91%84%E5%BD%B1?page=", "http://me2-sex.lofter.com/tag/%E6%AC%A7%E7%BE%8E?page=", "http://me2-sex.lofter.com/tag/%E6%A8%A1%E7%89%B9?page=", "http://me2-sex.lofter.com/tag/%E7%BE%8E%E5%AA%9B%E9%A6%86?page="}
    for _, v := range urlist {
        for i := 1; i <= 20; i++ {
            url := v + strconv.Itoa(i)
            w.Add(1)
            go GetAlbum(url)
            w.Wait()
        }
    }
}
func GetAlbum(url string) {
    data := GetUrl(url)
    body := string(data)
    part := regexp.MustCompile(`<a class="img" href="(.*)">`)
    match := part.FindAllStringSubmatch(body, -1)
    for _, v := range match {
        album <- v[1]
        w.Add(1)
        go GetItem()
    }
    w.Done()
}
func GetItem() {
    url := <-album
    defer func() {
        ret := recover()
        if ret != nil {
            log.Println(ret)
            w.Done()
        } else {
            w.Done()
        }
    }()
    data := GetUrl(url)
    if len(data) > 10 {
        body := string(data)
        part := regexp.MustCompile(`bigimgsrc="(.*)"`)
        match := part.FindAllStringSubmatch(body, -1)
        for _, v := range match {
            str := strings.Split(v[1], "/")
            length := len(str)
            source := GetUrl(v[1])
            name := str[length-1]
            file, err := os.Create(dir + name)
            if err != nil {
                panic(err)
            }
            size, err := file.Write(source)
            defer file.Close()
            if err != nil {
                panic(err)
            }
            log.Println(size)
        }
    }
}
func GetUrl(url string) []byte {
    ret, err := http.Get(url)
    if err != nil {
        log.Println(url)
        status := map[string]string{}
        status["status"] = "400"
        status["url"] = url
        panic(status)
    }
    body := ret.Body
    data, _ := ioutil.ReadAll(body)
    return data
}