Go语言圣经

package mainimport ("fmt""io""io/ioutil""net/http""os""strings""time")type results struct {url    stringresult string}func main() {start := time.Now()ch := make(chan string)result := make(map[string]string)for _, url := range os.Args[1:] {if !strings.HasPrefix(url, "http://") {url = "http://" + url}go fetch(url, ch)go fetch(url, ch)go fetch(url, ch)}for range os.Args[1:] {for i := 0; i < 3; i++ {fmt.Println(<-ch)}}for k, v := range result {fmt.Printf("%s : %s\n", k, v)}fmt.Printf("%.2fs elapsed\n", time.Since(start).Seconds())}func fetch(url string, ch chan<- string) {start := time.Now()resp, err := http.Get(url)if err != nil {ch <- fmt.Sprint(err)return}nbytes, err := io.Copy(ioutil.Discard, resp.Body)resp.Body.Close()if err != nil {ch <- fmt.Sprintf("while reading %s: %v", url, err)return}secs := time.Since(start).Seconds()ch <- fmt.Sprintf("%.2fs %7d %s", secs, nbytes, url)}