1. urlopen可以给一个Request Object返回一个response object，read()读取相应对象的内容，这时候的print(the_page)可以输出网页的html内容
1 import urllib2 2 3 req = urllib2.Request(‘http://www.voidspace.org.uk‘) 4 response = urllib2.urlopen(req) 5 the_page = response.read() 6 7 print(the_page)
2. Request对象可以给server传输数据，还可以传输一些额外信息(metadata)，如HTTP"headers"
3.如我们所知request可以用POST方式给server传输数据，这些数据可以通过标准方式进行编码之后进行传输，这里用了urlencode函数进行编码
1 import urllib2
2 import urllib
3
4 url = ‘http://www.someserver.com/cgi-bin/register.cgi‘
5
6 values = {‘name‘:‘Michael Foord‘,
7 ‘location‘: ‘Northampton‘,
8 ‘language‘: ‘Python‘
9 }
10
11 data = urllib.urlencode(values)
12 req = urllib2.Request(url, data)
13 response = urllib2.urlopen(req)
14
15 the_page = response.read()
当然也可以用GET模式来传输数据，默认没有加data参数的时候就是使用GET模式，实际上我们知道POST是将数据编码后打包发送，GET类似与将数据加在url的末尾进行传输
1 import urllib2
2 import urllib
3
4
5 values = {‘name‘:‘Michael Foord‘,
6 ‘location‘: ‘Northampton‘,
7 ‘language‘: ‘Python‘
8 }
9
10 data = urllib.urlencode(values)
11 print(data) # encoded data
12
13 url = ‘http://www.example.com/example.cgi‘
14 full_url = url + ‘?‘ + data #use ‘?‘ to add data at the end
15 req = urllib2.Request(full_url)
16 response = urllib2.urlopen(req)
17
18 the_page = response.read()
19 print(the_page)
４．Headers
一些服务器只提供给浏览器访问，而上面的方式默认以名字python-urllib/2.7进行访问，所以需要将自己“伪装”成浏览器的名字
1 import urllib
2 import urllib2
3
4 url = ‘http://www.someserver.com/cgi-bin/register.cgi‘
5 user_agent = ‘Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)‘
6
7 values = {‘name‘ : ‘Michael Foord‘,
8 ‘location‘ : ‘Northampton‘,
9 ‘language‘ : ‘Python‘ }
10
11 headers = { ‘User-Agent‘ : user_agent }
12 data = urllib.urlencode(values)
13
14 req = urllib2.Request(url, data, headers)
15 response = urllib2.urlopen(req)
16 the_page = response.read()
５. URLError with a "reason" attribute
1 import urllib 2 import urllib2 3 from urllib2 import URLError 4 5 req = urllib2.Request(‘http://www.pretend_server.org‘) 6 7 try: 8 urllib2.urlopen(req) 9 except URLError as e: 10 print e.reason
6. HTTPError with a "code" attribute, codes in the 100-299 range indicatesuccess, you will usually only see error codes in the 400-599 range.
1 import urllib 2 import urllib2 3 from urllib2 import URLError 4 5 req = urllib2.Request(‘http://www.python.org/fish.html‘) 6 7 try: 8 urllib2.urlopen(req) 9 except urllib2.HTTPError as e: 10 print e.code 11 print e.read()
7. Two basic approaches
1 #1 2 from urllib2 import Request, urlopen, URLError, HTTPError 3 4 req = Request(someurl) 5 6 try: 7 response = urlopen(req) 8 except HTTPError as e: 9 print ‘The server couldn\‘t fulfill the request.‘ 10 print ‘Error code: ‘, e.code 11 except URLError as e: 12 print ‘We failed to reach a server.‘ 13 print ‘Reason: ‘, e.reason 14 else: 15 print(‘everything is fine‘) 16 17 #2 18 from urllib2 import Request, urlopen, URLError 19 20 req = Request(someurl) 21 try: 22 response = urlopen(req) 23 except URLError as e: 24 if hasattr(e, ‘reason‘): 25 print ‘We failed to reach a server.‘ 26 print ‘Reason: ‘, e.reason 27 elif hasattr(e, ‘code‘): 28 print ‘The server couldn\‘t fulfill the request.‘ 29 print ‘Error code: ‘, e.code 30 else: 31 # everything is fine
8. Basic Authentication
当需要认证的时候，服务器会发出一个header来请求认证，如WWW-Authenticate: Basic realm="cPanel Users"，然后用户可以把用户名和密码作为一个header加在requese中再次请求.
一般不需要考虑格式范围的话可以直接用HTTPPasswordMgrWithDefaultRealm来设定某个URL的用户和密码
1 from urllib2 import Request, urlopen, URLError 2 import urllib2 3 4 #create a password manager 5 password_mgr = urllib2.HTTPPasswordMgrWithDefaultRealm() 6 7 username = ‘Prime‘ 8 password = ‘Bee‘ 9 10 top_level_url = "http://example.com/foo/" 11 password_mgr.add_password(None, top_level_url, username, password) 12 13 handler = urllib2.HTTPBasicAuthHandler(password_mgr) 14 15 opener = urllib2.build_opener(handler) 16 opener.open(someurl) 17 18 # Install the opener, not necessarily 19 urllib2.install_opener(opener)
9. 设置socket的默认等待时间
1 import socket 2 3 timeout = 10 4 socket.setdefaulttimeout(timeout)
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