[Python3.x]网络爬虫（三）：urllib.request抓资源的方式总结

转载自:http://blog.csdn.net/reymix/article/details/46869529

Python 3.X 要使用urllib.request 来抓取网络资源。

import urllib.request

response = urllib.request.urlopen('http://www.baidu.com')
buff = response.read()
html = buff.decode('utf8')
response.close()
print(html)

使用Request的方式:

import urllib.request

req = urllib.request.Request('http://www.lovejing.com')
response = urllib.request.urlopen(req)
buff = response.read()
html = buff.decode('utf8')
response.close()
print(html)

这种方式同样可以用来处理其他URL，例如FTP：

import urllib.request

req = urllib.request.Request('ftp://ftp.lovejing.com')
response = urllib.request.urlopen(req)
buff = response.read()
html = buff.decode('utf8')
response.close()
print(html)

使用POST请求：

import urllib.parseimport

urllib.requesturl = 'http://www.somebody.com/cgi-bin/register.cgi'
values = {'name' : 'Michael Foord',
'location' : 'Northampton',
'language' : 'Python' }
data = urllib.parse.urlencode(values)
req = urllib.request.Request(url, data)
response = urllib.request.urlopen(req)
the_page = response.read()

使用GET请求：

import urllib.request
import urllib.parse

data = {}
data['name'] = 'Somebody Here'
data['location'] = 'Northampton'
data['language'] = 'Python'
url_values = urllib.parse.urlencode(data)
print(url_values)
name=Somebody+Here&language=Python&location=Northampton
url = 'http://www.example.com/example.cgi'
full_url = url + '?' + url_values
data = urllib.request.open(full_url)

添加header：

import urllib.parse
import urllib.request

url = 'http://www.somebody.com/cgi-bin/register.cgi'
user_agent = 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'
values = {'name' : 'Michael Foord',
'location' : 'Northampton',
'language' : 'Python' }
headers = { 'User-Agent' : user_agent }
data = urllib.parse.urlencode(values)
req = urllib.request.Request(url, data, headers)
response = urllib.request.urlopen(req)
the_page = response.read()

错误处理:

import urllib.request
import urllib.error

req = urllib.request.Request('http://www.pretend_server.org')
try: urllib.request.urlopen(req)
except urllib.error.URLError as e:
print(e.reason)

返回的错误代码：

# Table mapping response codes to messages; entries have the

# form {code: (shortmessage, longmessage)}.

responses = {

100: ('Continue', 'Request received, please continue'),

101: ('Switching Protocols',

'Switching to new protocol; obey Upgrade header'),

200: ('OK', 'Request fulfilled, document follows'),

201: ('Created', 'Document created, URL follows'),

202: ('Accepted',

'Request accepted, processing continues off-line'),

203: ('Non-Authoritative Information', 'Request fulfilled from cache'),

204: ('No Content', 'Request fulfilled, nothing follows'),

205: ('Reset Content', 'Clear input form for further input.'),

206: ('Partial Content', 'Partial content follows.'),

300: ('Multiple Choices',

'Object has several resources -- see URI list'),

301: ('Moved Permanently', 'Object moved permanently -- see URI list'),

302: ('Found', 'Object moved temporarily -- see URI list'),

303: ('See Other', 'Object moved -- see Method and URL list'),

304: ('Not Modified',

'Document has not changed since given time'),

305: ('Use Proxy',

'You must use proxy specified in Location to access this '

'resource.'),

307: ('Temporary Redirect',

'Object moved temporarily -- see URI list'),

400: ('Bad Request',

'Bad request syntax or unsupported method'),

401: ('Unauthorized',

'No permission -- see authorization schemes'),

402: ('Payment Required',

'No payment -- see charging schemes'),

403: ('Forbidden',

'Request forbidden -- authorization will not help'),

404: ('Not Found', 'Nothing matches the given URI'),

405: ('Method Not Allowed',

'Specified method is invalid for this server.'),

406: ('Not Acceptable', 'URI not available in preferred format.'),

407: ('Proxy Authentication Required', 'You must authenticate with '

'this proxy before proceeding.'),

408: ('Request Timeout', 'Request timed out; try again later.'),

409: ('Conflict', 'Request conflict.'),

410: ('Gone',

'URI no longer exists and has been permanently removed.'),

411: ('Length Required', 'Client must specify Content-Length.'),

412: ('Precondition Failed', 'Precondition in headers is false.'),

413: ('Request Entity Too Large', 'Entity is too large.'),

414: ('Request-URI Too Long', 'URI is too long.'),

415: ('Unsupported Media Type', 'Entity body in unsupported format.'),

416: ('Requested Range Not Satisfiable',

'Cannot satisfy request range.'),

417: ('Expectation Failed',

'Expect condition could not be satisfied.'),

500: ('Internal Server Error', 'Server got itself in trouble'),

501: ('Not Implemented',

'Server does not support this operation'),

502: ('Bad Gateway', 'Invalid responses from another server/proxy.'),

503: ('Service Unavailable',

'The server cannot process the request due to a high load'),

504: ('Gateway Timeout',

'The gateway server did not receive a timely response'),

505: ('HTTP Version Not Supported', 'Cannot fulfill request.'),

}