Python爬虫学习==>第七章：urllib库的基本使用方法

学习目的：

　　urllib提供了url解析函数，所以需要学习
正式步骤

Step1：什么是urllib

　　urllib库是Python自带模块，是Python内置的HTTP请求库

　　包含4个模块：
　　

>>> import urllib
>>> # urllib.request　　请求模块
>>> # urllib.error　　异常处理模块
>>> # urllib.parse　　url解析模块
>>> # urllib.robotparser　　robot.txt解析模块

Step2：用法讲解

1. urlopen

   # -*-  coding:utf-8 -*
   
   import urllib.request
   
   '''
   urlopen语法格式如下
   urlopen(url, data=None, timeout=socket._GLOBAL_DEFAULT_TIMEOUT,*, cafile=None, capath=None, cadefault=False, context=None)
   '''
   #示例1
   response = urllib.request.urlopen('http://www.baidu.com')
   print(response.read().decode('utf-8'))    #read()方法是获取了response内容，然后指定编码打印出来,如果不加decode，那么打印则显示在一行
   
   print('\n')
   print('urllib.parse实例')
   print('\n')
   import urllib.request
   import urllib.parse
   
   data =  bytes(urllib.parse.urlencode({'word':'hello'}),encoding='utf-8')
   response = urllib.request.urlopen('http://httpbin.org/post',data=data)
   print(response.read())
   
   print('\n')
   print('urllib中的timeout用法和urllib.error异常处理模块')
   print('\n')
   
   import urllib.request
   import socket
   import urllib.error
   try:
       response = urllib.request.urlopen('http://httpbin.org/get',timeout=0.1)
   except urllib.error.URLError as e:
       if isinstance(e.reason,socket.error):
           print('TIMEOUT')

2. 响应

   # -*-  coding:utf-8 -*-
   
   print("响应类型实例")
   
   import urllib.request
   
   response = urllib.request.urlopen('http://www.baidu.com')
   print(type(response))

3. 状态码和响应头

   # -*-  coding:utf-8 -*-
   
   print('状态码和响应头的实例')
   
   import urllib.request
   
   response = urllib.request.urlopen('http://www.baidu.com')
   print(response.status)
   print(response.getheaders())
   print(response.getheader('Content-Type'))
   print(response.getheader('Date'))
   print(response.getheader('Server'))

   运行结果

   状态码和响应头的实例
   200
   [('Date', 'Tue, 03 Apr 2018 14:29:52 GMT'), ('Content-Type', 'text/html; charset=utf-8'), ('Transfer-Encoding', 'chunked'), ('Connection', 'Close'), ('Vary', 'Accept-Encoding'), ('Set-Cookie', 'BAIDUID=6150350FD6AF7F0B4629DA49AEF7DEAE:FG=1; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2147483647; path=/; domain=.baidu.com'), ('Set-Cookie', 'BIDUPSID=6150350FD6AF7F0B4629DA49AEF7DEAE; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2147483647; path=/; domain=.baidu.com'), ('Set-Cookie', 'PSTM=1522765792; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2147483647; path=/; domain=.baidu.com'), ('Set-Cookie', 'BDSVRTM=0; path=/'), ('Set-Cookie', 'BD_HOME=0; path=/'), ('Set-Cookie', 'H_PS_PSSID=1430_25809_13290_21093_20927; path=/; domain=.baidu.com'), ('P3P', 'CP=" OTI DSP COR IVA OUR IND COM "'), ('Cache-Control', 'private'), ('Cxy_all', 'baidu+66a85a47dcb1b7de8cd2d7ba25b3a1dc'), ('Expires', 'Tue, 03 Apr 2018 14:29:42 GMT'), ('X-Powered-By', 'HPHP'), ('Server', 'BWS/1.1'), ('X-UA-Compatible', 'IE=Edge,chrome=1'), ('BDPAGETYPE', ''), ('BDQID', '0xa1de1b2000003abd'), ('BDUSERID', '')]
   text/html; charset=utf-8
   Tue, 03 Apr 2018 14:29:52 GMT
   BWS/1.1

4. handler 代理

   # -*-  coding:utf-8 -*-
   import urllib.request
   
   proxy_hander = urllib.request.ProxyHandler(
       {'http':'http://127.0.0.1:9743','https':'https://127.0.0.1:9743'}
   )#代理以实际代理为准
   opener = urllib.request.build_opener(proxy_hander)
   response = opener.open('http://www.baidu.com')
   print(response.read())

5. cookie （记录用户身份的文本文件）

   # -*-  coding:utf-8 -*-
   import urllib.request,http.cookiejar
   #将cookie保存
   filename = 'cookie.txt'
   cookie = http.cookiejar.LWPCookieJar(filename)
   hander = urllib.request.HTTPCookieProcessor(cookie)
   opener = urllib.request.build_opener(hander)
   responer = opener.open('http://www.baidu.com')
   cookie.save(ignore_discard=True,ignore_expires=True)

   打印cookie

   # -*-  coding:utf-8 -*-
   
   import urllib.request,http.cookiejar
   
   #声明cookie为cookiejar对象
   cookie = http.cookiejar.CookieJar()
   #hander是处理浏览器中的cookie作用
   hander = urllib.request.HTTPCookieProcessor(cookie)
   #利用build_opener将cookie传给opener
   opener = urllib.request.build_opener(hander)
   responser = opener.open('http://www.baidu.com')
   for i in cookie:
       print(i.name + '=' + i.value)

   将本地的cookie值赋到浏览器

   # -*-  coding:utf-8 -*-
   
   import urllib.request,http.cookiejar
   
   cookie = http.cookiejar.LWPCookieJar()
   cookie.load('cookie.txt',ignore_discard=True,ignore_expires=True)
   hander = urllib.request.HTTPCookieProcessor(cookie)
   opener = urllib.request.build_opener(hander)
   response = opener.open('http://www.baidu.com')
   print(response.read().decode('utf-8'))

学习总结：

　　其余的内置方法未操作，直接学习下一节requests库