区别
- urllib2可以接受一个Request类的实例来设置URL请求的headers，urllib仅可以接受URL。这意味着，用urllib时不可以伪装User Agent字符串等。
- urllib提供urlencode方法用来encode发送的data，而urllib2没有。这是为何urllib常和urllib2一起使用的原因。
urllib
1 urllib.urlopen(url[,data[,proxies]])
打开一个url的方法，返回一个文件对象
>>> req = urllib.urlopen('http://www.baidu.com')
>>> req.readline() # 读取一行
'<!DOCTYPE html><!--STATUS OK--><html><head><meta http-equiv="content-type" content="text/html;charset=utf-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta content="always" name="referrer"><meta name="theme-color" content="#2932e1"><link rel="shortcut icon" href="/favicon.ico" type="image/x-icon" /><link rel="search" type="application/opensearchdescription+xml" href="/content-search.xml" title="xe7x99xbexe5xbaxa6xe6x90x9cxe7xb4xa2" /><link rel="icon" sizes="any" mask href="//www.baidu.com/img/baidu.svg"><link rel="dns-prefetch" href="//s1.bdstatic.com"/><link rel="dns-prefetch" href="//t1.baidu.com"/><link rel="dns-prefetch" href="//t2.baidu.com"/><link rel="dns-prefetch" href="//t3.baidu.com"/><link rel="dns-prefetch" href="//t10.baidu.com"/><link rel="dns-prefetch" href="//t11.baidu.com"/><link rel="dns-prefetch" href="//t12.baidu.com"/><link rel="dns-prefetch" href="//b1.bdstatic.com"/><title>xe7x99xbexe5xbaxa6xe4xb8x80xe4xb8x8bxefxbcx8cxe4xbdxa0xe5xb0xb1xe7x9fxa5xe9x81x93</title>
'
urlopen返回对象提供方法：
- read() , readline() ,readlines() , fileno() , close()：这些方法的使用方式与文件对象完全一样
- info()：返回一个httplib.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
2 urllib.urlretrieve(url[,filename[,reporthook[,data]]])
urlretrieve方法将url定位到的html文件下载到你本地的硬盘中。如果不指定filename，则会存为临时文件。
urlretrieve()返回一个二元组(filename,mine_hdrs)
>>> filename = urllib.urlretrieve('http://www.baidu.com')
>>> type(filename)
<type 'tuple'>
>>> filename
('/tmp/tmphngDjh', <httplib.HTTPMessage instance at 0x7fd5e03ea248>)
>>> filename = urllib.urlretrieve('http://www.baidu.com/',filename='/tmp/baidu')
>>> type(filename)
<type 'tuple'>
>>> filename
('/tmp/baidu', <httplib.HTTPMessage instance at 0x7fd5e03dbb48>)
3 urllib.urlcleanup()
清除由于urllib.urlretrieve()所产生的缓存
4 urllib.quote(url)和urllib.quote_plus(url)
将url数据获取之后，并将其编码，从而适用与URL字符串中，使其能被打印和被web服务器接受。
>>> urllib.quote('http://www.baidu.com')
'http%3A//www.baidu.com'
>>> urllib.quote_plus('http://www.baidu.com')
'http%3A%2F%2Fwww.baidu.com'
5 urllib.unquote(url)和urllib.unquote_plus(url)
与4的函数相反。
6 urllib.urlencode(query)
将URL中的键值对以连接符&划分
GET方法
>>> import urllib
>>> params=urllib.urlencode({'spam':1,'eggs':2,'bacon':0})
>>> params
'eggs=2&bacon=0&spam=1'
>>> f=urllib.urlopen("http://python.org/query?%s" % params)
>>> print f.read()
POST方法
>>> import urllib
>>> parmas = urllib.urlencode({'spam':1,'eggs':2,'bacon':0})
>>> f=urllib.urlopen("http://python.org/query", parmas)
>>> f.read()
urllib2
http://www.codefrom.com/paper/深入理解urllib、urllib2及requests
http://zhuoqiang.me/python-urllib2-usage.html
1 urllib2.urlopen()
>>> import urllib2
>>> url = 'http://www.baidu.com'
>>> req = urllib2.urlopen(url)
>>> req.readline()
'<!DOCTYPE html><!--STATUS OK--><html><head><meta http-equiv="content-type" content="text/html;charset=utf-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta content="always" name="referrer"><meta name="theme-color" content="#2932e1"><link rel="shortcut icon" href="/favicon.ico" type="image/x-icon" /><link rel="search" type="application/opensearchdescription+xml" href="/content-search.xml" title="xe7x99xbexe5xbaxa6xe6x90x9cxe7xb4xa2" /><link rel="icon" sizes="any" mask href="//www.baidu.com/img/baidu.svg"><link rel="dns-prefetch" href="//s1.bdstatic.com"/><link rel="dns-prefetch" href="//t1.baidu.com"/><link rel="dns-prefetch" href="//t2.baidu.com"/><link rel="dns-prefetch" href="//t3.baidu.com"/><link rel="dns-prefetch" href="//t10.baidu.com"/><link rel="dns-prefetch" href="//t11.baidu.com"/><link rel="dns-prefetch" href="//t12.baidu.com"/><link rel="dns-prefetch" href="//b1.bdstatic.com"/><title>xe7x99xbexe5xbaxa6xe4xb8x80xe4xb8x8bxefxbcx8cxe4xbdxa0xe5xb0xb1xe7x9fxa5xe9x81x93</title>
'
2 urllib2.Request()
>>> url = 'http://www.baidu.com'
>>> req = urllib2.Request(url)
>>> resp = urllib2.urlopen(req) #使用对象
>>> resp.readline()
'<!DOCTYPE html><!--STATUS OK--><html><head><meta http-equiv="content-type" content="text/html;charset=utf-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta content="always" name="referrer"><meta name="theme-color" content="#2932e1"><link rel="shortcut icon" href="/favicon.ico" type="image/x-icon" /><link rel="search" type="application/opensearchdescription+xml" href="/content-search.xml" title="xe7x99xbexe5xbaxa6xe6x90x9cxe7xb4xa2" /><link rel="icon" sizes="any" mask href="//www.baidu.com/img/baidu.svg"><link rel="dns-prefetch" href="//s1.bdstatic.com"/><link rel="dns-prefetch" href="//t1.baidu.com"/><link rel="dns-prefetch" href="//t2.baidu.com"/><link rel="dns-prefetch" href="//t3.baidu.com"/><link rel="dns-prefetch" href="//t10.baidu.com"/><link rel="dns-prefetch" href="//t11.baidu.com"/><link rel="dns-prefetch" href="//t12.baidu.com"/><link rel="dns-prefetch" href="//b1.bdstatic.com"/><title>xe7x99xbexe5xbaxa6xe4xb8x80xe4xb8x8bxefxbcx8cxe4xbdxa0xe5xb0xb1xe7x9fxa5xe9x81x93</title>
'
3 urllib2.Request(url[, data][, headers][, originreqhost][, unverifiable])
import urllib, urllib2
url = 'http://www.someserver.com/cgi-bin/register.cgi'
values = {'name' : 'Michael Foord', 'location' : 'Northampton', 'language' : 'Python' }
data = urllib.urlencode(values)
req = urllib2.Request(url, data) #send post
resp = urllib2.urlopen(req)
resp.read()
5 header
import urllib, urllib2
url = 'http://www.someserver.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.urlencode(values)
req = urllib2.Request(url, data, headers)
resp = urllib2.urlopen(req)
resp.read()
6 add_header(key, val)
import urllib2
req = urllib2.Request('http://www.example.com/')
req.add_header('Referer', 'http://www.python.org/')
resq = urllib2.urlopen(req)
7 PUT和DELETE方法
import urllib2
request = urllib2.Request(uri, data=data)
request.get_method = lambda: 'PUT' # or 'DELETE'
response = urllib2.urlopen(request)
注意
1. 如果只是单纯的下载或者显示下载进度，不对下载后的内容做处理等，比如下载图片，css，js文件等，可以用urlilb.urlretrieve()
2. 如果是下载的请求需要填写表单，输入账号，密码等，建议用urllib2.urlopen(urllib2.Request())
3. 在对字典数据编码时候，用到的是urllib.urlencode()