Urllib库是python内置的库
什么是Urllib
1.urllib.request 请求模块
2.urllib.error 异常处理模块
3.urllib.parse url解析模块
4.urllib.robotparser robots.txt解析模块
用法
-
urlopen
urllib.request.urlopen(url, data=None, [timeout, ]*, cafile=None, capath=None, cadefault=False, context=None)
GET类型的请求
import urllib.request response = urllib.request.urlopen('http://www.baidu.com') print(response.read().decode('utf-8'))POST类型的请求
import urllib.parse import urllib.request data = bytes(urllib.parse.urlencode({'word':'hello'}),encoding='utf8') response = urllib.request.urlopen('http://httpbin.org/post',data=data) print(response.read())带超时参数
response = urllib.request.urlopen('http://httpbin.org/get',timeout=1) print(response.read())测试较短的超时参数
import socket import urllib.request 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.timeout): print('TIMEOUT') else: print('It is OK!')查看urlopen返回值的类型
import urllib.request response = urllib.request.urlopen('https://www.python.org') print(type(response))输出结果:<class 'http.client.HTTPResponse'>
响应内容--状态码和响应头
import urllib.request
response = urllib.request.urlopen('https://www.python.org')
print(response.status)
print(response.getheaders())
print(response.getheader('Server'))
print(response.read().decode('utf-8')) #响应体，用utf-8解码
输出结果：
200
[('Server', 'nginx'), ('Content-Type', 'text/html; charset=utf-8'), ('X-Frame-Options', 'SAMEORIGIN'), ('x-xss-protection', '1; mode=block'), ('X-Clacks-Overhead', 'GNU Terry Pratchett'), ('Via', '1.1 varnish'), ('Content-Length', '48809'), ('Accept-Ranges', 'bytes'), ('Date', 'Sat, 18 Aug 2018 12:56:38 GMT'), ('Via', '1.1 varnish'), ('Age', '129'), ('Connection', 'close'), ('X-Served-By', 'cache-iad2128-IAD, cache-nrt6150-NRT'), ('X-Cache', 'HIT, HIT'), ('X-Cache-Hits', '2, 48'), ('X-Timer', 'S1534596999.663138,VS0,VE0'), ('Vary', 'Cookie'), ('Strict-Transport-Security', 'max-age=63072000; includeSubDomains')]
nginx
-
request方法
如果使用复杂的请求可以在urlopen方法中使用request参数，通过构造request参数可以方便的设定请求的方式。
import urllib.request
request = urllib.request.Request('https://python.org')
response = urllib.request.urlopen(request)
print(response.read().decode('utf-8'))
输出结果就是请求https://python.org的响应体。
使用POST方法发送请求，并用request构造函数构造request，作为参数调用urlopen
from urllib import request,parse
url = 'http://httpbin.org/post'
headers = {
'User-Agent':'Mozilla/4.0(bompatible;MSIE 5.5;Windows NT)',
'Host':'httpbin.org'
}
dict = {
'name':"Germey"
}
data = bytes(parse.urlencode(dict),encoding='utf8')
req = request.Request(url=url,data=data,headers=headers,method='POST')
response = request.urlopen(req)
print(response.read().decode('utf-8'))
依然是使用POST方法发送请求，用Request构造函数构造request，作为参数传递给urlopen，但request中的headers不在构造函数中指定，而在使用request.add_header添加header。如果有很多键值对要传递，可以用for循环多次调用add_header
from urllib import request,parse
url = 'http://httpbin.org/post'
dict = {
'name':'XieZ'
}
data = bytes(parse.urlencode(dict),encoding='utf8')
req = request.Request(url=url,data=data,method='POST')
req.add_header('User-Agent','Mozilla/4.0(compatible;MSIE 5.5;Windows NT)')
response = request.urlopen(req)
print(response.read().decode('utf-8'))
handler -- urllib中的高级用法，代理、cookie等等各种高级功能都是各种handler实现的。
-
代理
import urllib.request import urllib.request proxy_handler = urllib.request.ProxyHandler({ 'http':'http://127.0.0.1:9743', 'http':'https://127.0.0.1:9743' }) opener = urllib.request.build_opener(proxy_handler) response = opener.open('http://www.baidu.com') print(response.read()) -
Cookie--Cookie可以用来保存登录会话信息
import http.cookiejar,urllib.request cookie = http.cookiejar.CookieJar() 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)把Cookie保存至文件，方便将来爬虫使用cookie登录网站，保持登录状态
import http.cookiejar,urllib.request filename = "cookie.txt" cookie = http.cookiejar.MozillaCookieJar(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)这样Cookie就保存在文件中了，MozillaCookieJar是cookiejar的子类，是火狐浏览器的cookie保存格式，还有其他的cookie保存格式，比如LWPCookieJar。在使用时，用什么格式保存就用什么格式读取cookie就行
使用LWPCookieJar将cookie保存到文件，并且读取此文件中的cookie，并请求页面
import http.cookiejar,urllib.request filename = "cookie.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) mycookie = http.cookiejar.LWPCookieJar() mycookie.load('cookie.txt',ignore_discard=True,ignore_expires=True) handler = urllib.request.HTTPCookieProcessor(mycookie) opener = urllib.request.build_opener(handler) response = opener.open('http://www.baidu.com') print(response.read().decode('utf-8')) -
urllib的异常处理模块
from urllib import request,error try: response = request.urlopen('http://ljlhhljl.com/index.htm') except error.URLError as e: print(e.reason)结果显示：[Errno -2] Name or service not known
HTTPError含有reason、code、headers属性
from urllib import request,error try: response = request.urlopen('http://www.sina.com.cn/99999.html') except error.HTTPError as e: print(e.reason,e.code,e.headers,sep='\n') print('This is end of HTTPError\n') except error.URLError as e: print(e.reason) else: print('Request Sucessfully')结果显示： Not Found 404 Server: nginx Date: Sun, 19 Aug 2018 22:06:25 GMT Content-Type: text/html Transfer-Encoding: chunked Connection: close Vary: Accept-Encoding Age: 0 Via: http/1.1 ctc.nanjing.ha2ts4.77 (ApacheTrafficServer/6.2.1 [cMsSf ]) X-Cache: MISS.77 X-Via-CDN: f=edge,s=ctc.nanjing.ha2ts4.65.nb.sinaedge.com,c=61.171.236.224;f=Edge,s=ctc.nanjing.ha2ts4.77,c=202.102.94.65 X-Via-Edge: 1534716385494e0ecab3d7c5e66ca3150b8e6 This is end of HTTPError -
URL解析模块--urlparse和urlunparse
1.urlparse函数from urllib.parse import urlparse result = urlparse('http://www.baidu.com/index.html;user?id=5#comment') print(type(result),result)*返回结果：<class 'urllib.parse.ParseResult'> ParseResult(scheme='http', netloc='www.baidu.com', path='/index.html', params='user', query='id=5', fragment='comment')
2.urlunparse函数
from urllib.parse import urlunparse
data = ['http','www.baidu.com','index.html','user','a=6','comment']
print(urlunparse(data))
*返回结果：http://www.baidu.com/index.html;user?a=6#comment
urlunparse就是urlparse的反函数，把各种参数拼接为一个url
3.urljpin函数
from urllib.parse import urljoin
print(urljoin('http://www.baidu.com','FAQ.html'))
print(urljoin('http://www.baidu.com','https://lllll.com/FAQ.html'))
*返回结果:http://www.baidu.com/FAQ.html
https://lllll.com/FAQ.html
4.urlencode--可以把字典对象转换成get请求参数，很常用
from urllib.parse import urlencode
params = {
'name':'xiezheng',
'age':23
}
base_url = 'http://www.baidu.com?'
url = base_url + urlencode(params)
print(url)
*返回结果:http://www.baidu.com?name=xiezheng&age=23
- urllib.robotparser模块，用来解析robot.txt文件
