Go语言通过http抓取网页的方法

package main
import (
 "fmt"
 "log"
 "net/http"
 "net/url"
 "io/ioutil"
)
//指定代理ip
func getTransportFieldURL(proxy_addr *string) (transport *http.Transport) {
 url_i := url.URL{}
 url_proxy, _ := url_i.Parse(*proxy_addr)
 transport = &http.Transport{Proxy : http.ProxyURL(url_proxy)}
 return
}
//从环境变量$http_proxy或$HTTP_PROXY中获取HTTP代理地址
func getTransportFromEnvironment() (transport *http.Transport) {
 transport = &http.Transport{Proxy : http.ProxyFromEnvironment}
 return
}
func fetch(url , proxy_addr *string) (html string) {
 transport := getTransportFieldURL(proxy_addr)
 client := &http.Client{Transport : transport}
 req, err := http.NewRequest("GET", *url, nil)
 if err != nil {
  log.Fatal(err.Error())
 }
 resp, err := client.Do(req)
 if err != nil {
  log.Fatal(err.Error())
 }
 if resp.StatusCode == 200 {
  robots, err := ioutil.ReadAll(resp.Body);
  resp.Body.Close()
  if err != nil {
   log.Fatal(err.Error())
  }
  html = string(robots);
 } else {
  html = ""
 }
 return
}
func main() {
 proxy_addr := "http://183.221.250.137:80/"
 url := "http://www.baidu.com/s?wd=ip"
 html := fetch(&url, &proxy_addr)
 fmt.Println(html)
}