Go - チュートリアル - URLからの取得(net/httpパッケージ(Get関数、構造体(Response)、StatusCodeフィールド))

開発環境

macOS Mojave - Apple (OS)
Emacs (Text Editor)
Windows 10 Pro (OS)
Visual Studio Code (Text Editor)
Go (プログラミング言語)

プログラミング言語Go (ADDISON-WESLEY PROFESSIONAL COMPUTING SERIES) (Alan A.A. Donovan(著)、Brian W. Kernighan(著)、柴田芳樹(翻訳)、丸善出版)の第1章(チュートリアル)、1.5(URLからの取得)、練習問題1.9の解答を求めてみる。

コード

package main

import (
 "fmt"
 "io"
 "net/http"
 "os"
 "strings"
)

func main() {
 for _, url := range os.Args[1:] {
  fmt.Println(url)
  if !(strings.HasPrefix(url, "http://") ||
   strings.HasPrefix(url, "https://")) {
   url = "http://" + url
   fmt.Println(url)
  }
  resp, err := http.Get(url)
  if err != nil {
   fmt.Fprintf(os.Stderr, "fetch: %v\n", err)
   os.Exit(1)
  }
  fmt.Printf("HTTPテータスコード: %d\n", resp.StatusCode)
  _, err = io.Copy(os.Stdout, resp.Body)
  resp.Body.Close()
  if err != nil {
   fmt.Fprintf(os.Stderr, "fetch: reading %s: %v\n", url, err)
   os.Exit(1)
  }
 }
}

入出力結果(Terminal, cmd(コマンドプロンプト))

$ go run sample9.go example.com jp-kamimura.com
example.com
http://example.com
HTTPテータスコード: 200
<!doctype html>
<html>
<head>
    <title>Example Domain</title>

    <meta charset="utf-8" />
    <meta http-equiv="Content-type" content="text/html; charset=utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <style type="text/css">
    body {
        background-color: #f0f0f2;
        margin: 0;
        padding: 0;
        font-family: "Open Sans", "Helvetica Neue", Helvetica, Arial, sans-serif;
        
    }
    div {
        width: 600px;
        margin: 5em auto;
        padding: 50px;
        background-color: #fff;
        border-radius: 1em;
    }
    a:link, a:visited {
        color: #38488f;
        text-decoration: none;
    }
    @media (max-width: 700px) {
        body {
            background-color: #fff;
        }
        div {
            width: auto;
            margin: 0 auto;
            border-radius: 0;
            padding: 1em;
        }
    }
    </style>    
</head>

<body>
<div>
    <h1>Example Domain</h1>
    <p>This domain is established to be used for illustrative examples in documents. You may use this
    domain in examples without prior coordination or asking for permission.</p>
    <p><a href="http://www.iana.org/domains/example">More information...</a></p>
</div>
</body>
</html>
jp-kamimura.com
http://jp-kamimura.com
HTTPテータスコード: 530
<!DOCTYPE html>
<!--[if lt IE 7]> <html class="no-js ie6 oldie" lang="en-US"> <![endif]-->
<!--[if IE 7]>    <html class="no-js ie7 oldie" lang="en-US"> <![endif]-->
<!--[if IE 8]>    <html class="no-js ie8 oldie" lang="en-US"> <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js" lang="en-US"> <!--<![endif]-->
<head>
<title>Origin DNS error | jp-kamimura.com | Cloudflare</title>
<meta charset="UTF-8" />
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=Edge,chrome=1" />
<meta name="robots" content="noindex, nofollow" />
<meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1" />
<link rel="stylesheet" id="cf_styles-css" href="/cdn-cgi/styles/cf.errors.css" type="text/css" media="screen,projection" />
<!--[if lt IE 9]><link rel="stylesheet" id='cf_styles-ie-css' href="/cdn-cgi/styles/cf.errors.ie.css" type="text/css" media="screen,projection" /><![endif]-->
<style type="text/css">body{margin:0;padding:0}</style>


<!--[if gte IE 10]><!--><script type="text/javascript" src="/cdn-cgi/scripts/zepto.min.js"></script><!--<![endif]-->
<!--[if gte IE 10]><!--><script type="text/javascript" src="/cdn-cgi/scripts/cf.common.js"></script><!--<![endif]-->



</head>
<body>
  <div id="cf-wrapper">
    <div class="cf-alert cf-alert-error cf-cookie-error" id="cookie-alert" data-translate="enable_cookies">Please enable cookies.</div>
    <div id="cf-error-details" class="cf-error-details-wrapper">
      <div class="cf-wrapper cf-header cf-error-overview">
        <h1>
          <span class="cf-error-type" data-translate="error">Error</span>
          <span class="cf-error-code">1016</span>
          <small class="heading-ray-id">Ray ID: 497555cda2c9aed5 &bull; 2019-01-11 06:30:31 UTC</small>
        </h1>
        <h2 class="cf-subheadline">Origin DNS error</h2>
      </div><!-- /.header -->

      <section></section><!-- spacer -->

      <div class="cf-section cf-wrapper">
        <div class="cf-columns two">
          <div class="cf-column">
            <h2 data-translate="what_happened">What happened?</h2>
            <p>You've requested a page on a website (jp-kamimura.com) that is on the <a data-orig-proto="https" data-orig-ref="www.cloudflare.com/5xx-error-landing?utm_source=error_100x" target="_blank">Cloudflare</a> network. Cloudflare is currently unable to resolve your requested domain (jp-kamimura.com).
          </div>

          
          <div class="cf-column">
            <h2 data-translate="what_can_i_do">What can I do?</h2>
            <p><strong>If you are a visitor of this website:</strong><br />Please try again in a few minutes.</p><p><strong>If you are the owner of this website:</strong><br />Check your DNS settings. If you are using a CNAME origin record, make sure it is valid and resolvable. <a href="https://support.cloudflare.com/hc/en-us/articles/234979888-Error-1016-Origin-DNS-error">Additional troubleshooting information here.</a></p>
          </div>
          
        </div>
      </div><!-- /.section -->

      <div class="cf-error-footer cf-wrapper">
  <p>
    <span class="cf-footer-item">Cloudflare Ray ID: <strong>497555cda2c9aed5</strong></span>
    <span class="cf-footer-separator">&bull;</span>
    <span class="cf-footer-item"><span>Your IP</span>: 202.222.48.65</span>
    <span class="cf-footer-separator">&bull;</span>
    <span class="cf-footer-item"><span>Performance &amp; security by</span> <a href="https://www.cloudflare.com/5xx-error-landing?utm_source=error_footer" id="brand_link" target="_blank">Cloudflare</a></span>
    
  </p>
</div><!-- /.error-footer -->


    </div><!-- /#cf-error-details -->
  </div><!-- /#cf-wrapper -->

  <script type="text/javascript">
  window._cf_translation = {};
  
  
</script>

</body>
</html>
$

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2019年1月11日金曜日

Go - チュートリアル - URLからの取得(net/httpパッケージ(Get関数、構造体(Response)、StatusCodeフィールド))

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