python模块—urllib

1. 网页操作

urllib.urlopen(url[,data[,proxies]])

打开一个url，返回一个文件对象，然后可以进行类似文件对象操作

url：远程数据的路径，即网址

data：表示以GET或者POST方式请求url的数据
proxes：设置代理

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

 >>> import urllib

 >>> resp = urllib.urlopen("http://www.google.com")

 >>> read = resp.read()   ######读取整个文件

 >>> print read

 ............此处打印整个页面代码,略之.............

 >>> readline = resp.readline() ######读取一行

 >>> print readline

 <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="zh-HK"><head><meta content="/images/branding/googleg/1x/googleg_standard_color_128dp.png" itemprop="image"><title>Google</title><script>(function(){window.google={kEI:'KhMBVtO1KuGQmgWe2ILYDQ',kEXPI:'3700263,4014829,4024207,4027916,4029815,4031109,4032235,4032500,4032678,4033307,4033344,4034882,4036527,4037333,4037569,4037934,4038012,4041302,4041323,4041440,4041507,4041837,4042160,4042180,4043255,4043411,4043457,4043459,4043491,4043564,4044246,4044336,4044339,4044343,4044606,4044852,4044864,4045003,4045414,4045711,4045717,4045764,4045841,4045871,4046059,4046121,4046304,4046340,4046606,4046717,4047133,4047530,4047599,4047668,4047751,4048048,4048125,8300200,8300203,8501987,8501992,8502156,10200083',authuser:0,kscs:'c9c918f0_10'};google.kHL='zh-HK';})();(function(){google.lc=[];google.li=0;google.getEI=function(a){for(var b;a&&(!a.getAttribute||!(b=a.getAttribute("eid")));)a=a.parentNode;return b||google.kEI};google.getLEI=function(a){for(var b=null;a&&(!a.getAttribute||!(b=a.getAttribute("leid")));)a=a.parentNode;return b};google.https=function(){return"https:"==window.location.protocol};google.ml=function(){return null};google.time=function(){return(new Date).getTime()};google.log=function(a,b,d,e,g){a=google.logUrl(a,b,d,e,g);if(""!=a){b=new Image;var c=google.lc,f=google.li;c[f]=b;b.onerror=b.onload=b.onabort=function(){delete c[f]};window.google&&window.google.vel&&window.google.vel.lu&&window.google.vel.lu(a);b.src=a;google.li=f+1}};google.logUrl=function(a,b,d,e,g){var c="",f=google.ls||"";if(!d&&-1==b.search("&ei=")){var h=google.getEI(e),c="&ei="+h;-1==b.search("&lei=")&&((e=google.getLEI(e))?c+="&lei="+e:h!=google.kEI&&(c+="&lei="+google.kEI))}a=d||"/"+(g||"gen_204")+"?atyp=i&ct="+a+"&cad="+b+c+f+"&zx="+google.time();/^http:/i.test(a)&&google.https()&&(google.ml(Error("a"),!1,{src:a,glmm:1}),a="");return a};google.y={};google.x=function(a,b){google.y[a.id]=[a,b];return!1};google.load=function(a,b,d){google.x({id:a+k++},function(){google.load(a,b,d)})};var k=0;})();var _gjwl=location;function _gjuc(){var a=_gjwl.href.indexOf("#");if(0<=a&&(a=_gjwl.href.substring(a),0<a.indexOf("&q=")||0<=a.indexOf("#q="))&&(a=a.substring(1),-1==a.indexOf("#"))){for(var d=0;d<a.length;){var b=d;"&"==a.charAt(b)&&++b;var c=a.indexOf("&",b);-1==c&&(c=a.length);b=a.substring(b,c);if(0==b.indexOf("fp="))a=a.substring(0,d)+a.substring(c,a.length),c=d;else if("cad=h"==b)return 0;d=c}_gjwl.href="/search?"+a+"&cad=h";return 1}return 0}

 >>> readlines = resp.readlines() ######逐行读取

 >>> print readlines

 .............................略之.................................

 >>> fileno = resp.fileno()  ######返回整数的底层实现使用请求从操作系统的I/O操作的文件描述符

 >>> print fileno

 3

 >>> info = resp.info()

 >>> print info

 Date: Tue, 22 Sep 2015 08:36:58 GMT

 Expires: -1

 Cache-Control: private, max-age=0

 Content-Type: text/html; charset=Big5

 P3P: CP="This is not a P3P policy! See http://www.google.com/support/accounts/bin/answer.py?hl=en&answer=151657 for more info."

 Server: gws

 X-XSS-Protection: 1; mode=block

 X-Frame-Options: SAMEORIGIN

 Set-Cookie: PREF=ID=1111111111111111:FF=0:NW=1:TM=1442911018:LM=1442911018:V=1:S=mEKtFlZwAwUmso5J; expires=Thu, 31-Dec-2015 16:02:17 GMT; path=/; domain=.google.com.hk

 Set-Cookie: NID=71=CqIYFwoA4vkAAu_Zu8X_IEElnFUbjPTO-BHG1zq9MjE6GQZbQX7ZArRNmDPL0p0cmSBu3GEX_H4S_DqGfFSYUzSWzlQhKGp16nNK2kP25iJwWrCxmxdJ_2xbFvwhhkSxQrdC5g; expires=Wed, 23-Mar-2016 08:36:58 GMT; path=/; domain=.google.com.hk; HttpOnly

 Accept-Ranges: none

 Vary: Accept-Encoding

 >>> statuscode = resp.getcode()

 >>> print statuscode

 200

 >>> url = resp.geturl()

 >>> print url

 http://www.google.com.hk/?gws_rd=cr

2. 下载

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表示保存到本地的路径，mine_hdrs返回一个httplib.HTTPMessage实例，表示服务器的响应头

filename：指定了保存到本地的路径（如果未指定该参数，urllib会生成一个临时文件来保存数据）
reporthook：是一个回调函数，当连接上服务器、以及相应的数据块传输完毕的时候会触发该回调。我们可以利用这个回调函数来显示当前的下载进度
data：指POST或者GET到服务器的数据

 >>> filename = urllib.urlretrieve('http://www.google.com.hk/')

 >>> type(filename)

 <type 'tuple'>

 >>> filename[0]

 '/tmp/tmp8eVLjq'

 >>> filename[1]

 <httplib.HTTPMessage instance at 0xb6a363ec>

临时存放

 >>> filename = urllib.urlretrieve('http://www.google.com.hk/',filename='/home/dzhwen/python文件/Homework/urllib/google.html')

 >>> type(filename)

 <type 'tuple'>

 >>> filename[0]

 '/home/dzhwen/python\xe6\x96\x87\xe4\xbb\xb6/Homework/urllib/google.html'

 >>> filename[1]

 <httplib.HTTPMessage instance at 0xb6e2c38c>

保存为本地

 import urllib

 def cbk(a,b,c):

     '''回调函数

     @a: 已经下载的数据块

     @b: 数据块的大小

     @c: 远程文件的大小

     '''

     per = 100.0 * a * b / c

     if per > 100:

         per = 100

     print '%.2f%%' % per

 url = 'http://www.sina.com.cn'

 local = '/py/sina.html'

 urllib.urlretrieve(url, local, cbk)

下载进度实例

urllib.urlcleanup()

清除由于urllib.urlretrieve()所产生的缓存

3. 编码与解码

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'

urllib.unquote(url)和urllib.unquote_plus(url)

与urllib.quote(url)和urllib.quote_plus(url)函数相反

urllib.urlencode(query)

将URL中的键值对以连接符&划分

这里可以与urlopen结合以实现get方法和post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()

GET方法

 >>> import urllib

 >>> parmas = urllib.urlencode({'spam':1,'eggs':2,'bacon':0})

 >>> f=urllib.urlopen("http://python.org/query",parmas)

 >>> f.read()

POST方法

补充：

quote(s, safe='/')

对字符串进行编码，参数safe指定了不需要编码的字符，默认不编码字符/。

pathname2url(pathname)

将本地路径转换为url路经

url2pathname(pathname)

将url路经转换为本地路径