urllib库

python内置的最基本的HTTP请求库，有以下四个模块：

urllib.request　　请求模块

urllib.error　　　 异常处理模块

urllib.parse　　　url解析模块

urllib.robotparser  robots.txt解析模块

urllib.request请求模块：

urllib.request.urlopen(url,data=None,[timeout,]*,cafile=None,capath=None,cadefault=False,context=None)

'''urlopen()函数'''

import urllib.request

response = urllib.request.urlopen("http://www.baidu.com")

print(response.read().decode("utf-8"))    #response.read()是bytes类型的数据，要转码。

import urllib.parse
data = bytes(urllib.parse.urlencode({'word':'hello'}),encoding='utf-8')
#该提交方式是post，data参数是bytes类型的键值对对象
response = urllib.request.urlopen("http://httpbin.org/post",data=data)  #专门提供做http测试的网站
print(response.read())

#timeout是超时响应参数

response = urllib.request.urlopen("http://httpbin.org/get",timeout=1)

print(response.read())

import socket
import urllib.error
try:
    urllib.request.urlopen("http://httpbin.org/get", timeout=0.1)
except urllib.error.URLError as e:
    if isinstance(e.reason,socket.timeout):
        print('TIME OUT')

#响应类型
print(type(response))

#响应头、状态码
response = urllib.request.urlopen("https://www.python.org")
print(response.status)  #得到响应的状态码
print(response.getheaders())    #得到响应的Response Headers
print(response.getheader("Server")) #根据键得到Response Headers中指定键的值

'''Request()函数：当urlopen()要传递headers等信息时候，就要用到Request()函数，
返回一个request对象作为urlopen()函数的一个参数。'''
import urllib.parse
url = "http://httpbin.org/post"
headers = {
    # 'User-Agent':'Mozilla/4.0(compatible;MSIE 5.5;Windows NT)',
    'Host':'httpbin.org'
}
dict = {
    'name':'Germey'
}
data = bytes(urllib.parse.urlencode(dict),encoding='utf-8')
req = urllib.request.Request(url=url,data=data,headers=headers,method='POST')
req.add_header('User-Agent','Mozilla/4.0(compatible;MSIE 5.5;Windows NT)')  #可以单独添加header
response = urllib.request.urlopen(req)
print(response.read().decode('utf-8'))

'''cookie'''
import http.cookiejar,urllib.request
cookie = http.cookiejar.MozillaCookieJar()
handler = urllib.request.HTTPCookieProcessor(cookie)
opener = urllib.request.build_opener(handler)
response = opener.open("http://www.baidu.com")
for item in cookie:
    print(item.name + "=: " + item.value)

#存储cookie
filename = "cookieLWP.txt"
cookie = http.cookiejar.LWPCookieJar(filename)
handler = urllib.request.HTTPCookieProcessor(cookie)
opener = urllib.request.build_opener(handler)
response = opener.open("http://www.baidu.com")
cookie.save(ignore_discard=True,ignore_expires=True)
#读取cookie
cookie = http.cookiejar.LWPCookieJar()  #怎么存就怎么取
cookie.load('cookieLWP.txt',ignore_discard=True,ignore_expires=True)
handler = urllib.request.HTTPCookieProcessor(cookie)
opener = urllib.request.build_opener(handler)
response = opener.open("http://www.baidu.com")
print(response.read().decode('utf-8'))

urllib.error异常处理模块：

'''异常处理'''
from urllib import error
try:
    response = urllib.request.urlopen("https://www.cnblogs.com/wisir/index.html")
except error.HTTPError as e:
    print(e.reason,e.code,e.headers,sep='\n')
except error.URLError as e:
    print(e.reason)
else:
    print("Request Successfully")

try:
    response = urllib.request.urlopen("https://www.baidu.com",timeout=0.01)
except urllib.error.URLError as e:
    print(e.reason)
    if isinstance(e.reason,socket.timeout):
        print('TIME OUT')

urllib.parse URL解析模块：

'''urlparse'''
# urllib.parse.urlparse(urlstring,scheme="",allow_fragments=True)
from urllib.parse import urlparse
result = urlparse("http://www.baidu.com/index.html;user?id=5#comment")
print(type(result),result)

'''urlunparse：作用与urlparse相反，是将ParseResult类型的六个参数，合成一个完整的url。'''
from urllib.parse import urlunparse
data = ['http','www.baidu.com','index.html','user','a=6','comment']
print(urlunparse(data))

'''urljoin：以第二个参数为基准，若第二个参数没有ParseResult类型六个参数中的某一个，则用第一个参数作为补充。'''
from urllib.parse import urljoin
print(urljoin("http://www.baidu.com","FAQ.html"))
print(urljoin("http://www.baidu.com","https://www.cnblogs.com/wisir/"))

'''urlencode：字典对象转换为get请求参数'''
from urllib.parse import urlencode
params = {
    'name':'germey',
    'age':22
}
base_url = "http://www.baidu.com?"
url = base_url + urlencode(params)
print(url)

python3 urllib库官方文档：https://docs.python.org/3/library/urllib.html