python3实现抓取网页资源的 N 种方法

这两天学习了python3实现抓取网页资源的方法，发现了很多种方法，所以，今天添加一点小笔记。

1、最简单

    import urllib.request
    response = urllib.request.urlopen('http://python.org/')
    html = response.read() 

2、使用 Request

    import urllib.request

    req = urllib.request.Request('http://python.org/')
    response = urllib.request.urlopen(req)
    the_page = response.read()

3、发送数据

    #! /usr/bin/env python3

    import urllib.parse
    import urllib.request

    url = 'http://localhost/login.php'
    user_agent = 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'
    values = {
         'act' : 'login',
         'login[email]' : 'yzhang@i9i8.com',
         'login[password]' : '123456'
         }

    data = urllib.parse.urlencode(values)
    req = urllib.request.Request(url, data)
    req.add_header('Referer', 'http://www.python.org/')
    response = urllib.request.urlopen(req)
    the_page = response.read()

    print(the_page.decode("utf8"))

4、发送数据和header

    #! /usr/bin/env python3

    import urllib.parse
    import urllib.request

    url = 'http://localhost/login.php'
    user_agent = 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'
    values = {
         'act' : 'login',
         'login[email]' : 'yzhang@i9i8.com',
         'login[password]' : '123456'
         }
    headers = { 'User-Agent' : user_agent }

    data = urllib.parse.urlencode(values)
    req = urllib.request.Request(url, data, headers)
    response = urllib.request.urlopen(req)
    the_page = response.read()

    print(the_page.decode("utf8"))

5、http 错误

    #! /usr/bin/env python3

    import urllib.request

    req = urllib.request.Request('http://www.python.org/fish.html')
    try:
      urllib.request.urlopen(req)
    except urllib.error.HTTPError as e:
      print(e.code)
      print(e.read().decode("utf8"))

6、异常处理1

    #! /usr/bin/env python3

    from urllib.request import Request, urlopen
    from urllib.error import URLError, HTTPError
    req = Request("http://twitter.com/")
    try:
      response = urlopen(req)
    except HTTPError as e:
      print('The server couldn\'t fulfill the request.')
      print('Error code: ', e.code)
    except URLError as e:
      print('We failed to reach a server.')
      print('Reason: ', e.reason)
    else:
      print("good!")
      print(response.read().decode("utf8"))

7、异常处理2

    #! /usr/bin/env python3

    from urllib.request import Request, urlopen
    from urllib.error import URLError
    req = Request("http://twitter.com/")
    try:
      response = urlopen(req)
    except URLError as e:
      if hasattr(e, 'reason'):
        print('We failed to reach a server.')
        print('Reason: ', e.reason)
      elif hasattr(e, 'code'):
        print('The server couldn\'t fulfill the request.')
        print('Error code: ', e.code)
    else:
      print("good!")
      print(response.read().decode("utf8"))

8、HTTP 认证

    #! /usr/bin/env python3

    import urllib.request

    # create a password manager
    password_mgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()

    # Add the username and password.
    # If we knew the realm, we could use it instead of None.
    top_level_url = "https://cms.tetx.com/"
    password_mgr.add_password(None, top_level_url, 'yzhang', 'cccddd')

    handler = urllib.request.HTTPBasicAuthHandler(password_mgr)

    # create "opener" (OpenerDirector instance)
    opener = urllib.request.build_opener(handler)

    # use the opener to fetch a URL
    a_url = "https://cms.tetx.com/"
    x = opener.open(a_url)
    print(x.read())

    # Install the opener.
    # Now all calls to urllib.request.urlopen use our opener.
    urllib.request.install_opener(opener)

    a = urllib.request.urlopen(a_url).read().decode('utf8')
    print(a)

9、使用代理

    #! /usr/bin/env python3

    import urllib.request

    proxy_support = urllib.request.ProxyHandler({'sock5': 'localhost:1080'})
    opener = urllib.request.build_opener(proxy_support)
    urllib.request.install_opener(opener)


    a = urllib.request.urlopen("http://g.cn").read().decode("utf8")
    print(a)

10、超时

    #! /usr/bin/env python3

    import socket
    import urllib.request

    # timeout in seconds
    timeout = 2
    socket.setdefaulttimeout(timeout)

    # this call to urllib.request.urlopen now uses the default timeout
    # we have set in the socket module
    req = urllib.request.Request('http://twitter.com/')
    a = urllib.request.urlopen(req).read()
    print(a)

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。