Python3学习urllib的使用方法示例

urllib是python的一个获取url(Uniform Resource Locators,统一资源定址符)了，可以利用它来抓取远程的数据进行保存，本文整理了一些关于urllib使用中的一些关于header,代理,超时,认证,异常处理处理方法。

1.基本方法

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

url: 需要打开的网址 data：Post提交的数据 timeout：设置网站的访问超时时间

直接用urllib.request模块的urlopen（）获取页面，page的数据格式为bytes类型，需要decode（）解码，转换成str类型。

from urllib import request
response = request.urlopen(r'http://python.org/') # <http.client.HTTPResponse object at 0x00000000048BC908> HTTPResponse类型
page = response.read()
page = page.decode('utf-8')

urlopen返回对象提供方法：

read() , readline() ,readlines() , fileno() , close() ：对HTTPResponse类型数据进行操作 info()：返回HTTPMessage对象，表示远程服务器返回的头信息 getcode()：返回Http状态码。如果是http请求，200请求成功完成;404网址未找到 geturl()：返回请求的url

1、简单读取网页信息

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

2、使用request

urllib.request.Request(url, data=None, headers={}, method=None)

使用request（）来包装请求，再通过urlopen（）获取页面。

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

3、发送数据，以登录知乎为例

''''' 
Created on 2016年5月31日 
 
@author: gionee 
''' 
import gzip 
import re 
import urllib.request 
import urllib.parse 
import http.cookiejar 
 
def ungzip(data): 
  try: 
    print("尝试解压缩...") 
    data = gzip.decompress(data) 
    print("解压完毕") 
  except: 
    print("未经压缩，无需解压") 
   
  return data 
     
def getXSRF(data): 
  cer = re.compile('name="_xsrf" value="(.*)"',flags = 0) 
  strlist = cer.findall(data) 
  return strlist[0] 
 
def getOpener(head): 
  # cookies 处理 
  cj = http.cookiejar.CookieJar() 
  pro = urllib.request.HTTPCookieProcessor(cj) 
  opener = urllib.request.build_opener(pro) 
  header = [] 
  for key,value in head.items(): 
    elem = (key,value) 
    header.append(elem) 
  opener.addheaders = header 
  return opener 
# header信息可以通过firebug获得 
header = { 
  'Connection': 'Keep-Alive', 
  'Accept': 'text/html, application/xhtml+xml, */*', 
  'Accept-Language': 'en-US,en;q=0.8,zh-Hans-CN;q=0.5,zh-Hans;q=0.3', 
  'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:46.0) Gecko/20100101 Firefox/46.0', 
  'Accept-Encoding': 'gzip, deflate', 
  'Host': 'www.zhihu.com', 
  'DNT': '1' 
} 
 
url = 'http://www.zhihu.com/' 
opener = getOpener(header) 
op = opener.open(url) 
data = op.read() 
data = ungzip(data) 
_xsrf = getXSRF(data.decode()) 
 
url += "login/email" 
email = "登录账号" 
password = "登录密码" 
postDict = { 
  '_xsrf': _xsrf, 
  'email': email, 
  'password': password, 
  'rememberme': 'y'  
} 
postData = urllib.parse.urlencode(postDict).encode() 
op = opener.open(url,postData) 
data = op.read() 
data = ungzip(data) 
 
print(data.decode()) 

4、http错误

import urllib.request 
req = urllib.request.Request('http://www.lz881228.blog.163.com ') 
try: 
  urllib.request.urlopen(req) 
except urllib.error.HTTPError as e: 
print(e.code) 
print(e.read().decode("utf8")) 

5、异常处理

from urllib.request import Request, urlopen 
from urllib.error import URLError, HTTPError 
 
req = Request("http://www.abc.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")) 

6、http认证

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://www.lsjlt.com /" 
password_mgr.add_password(None, top_level_url, 'rekfan', 'xxxxxx') 
 
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://www.lsjlt.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) 

7、使用代理

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://www.baidu.com ").read().decode("utf8") 
print(a) 

8、超时

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://www.lsjlt.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编程网。