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[PYTHON] 核心编程笔记(20.Web编程)

showerlee 2014-01-04 14:39 Dev, PYTHON 阅读 (3,914) 抢沙发

20.1 介绍

20.1.1 Web应用:客户端/服务器计算

20.1.2 因特网

20.2 使用Python进行Web应用:创建一个简单的Web客户端

20.2.1 统一资源定位符

20.2.2 urlparse模块

urlparse(urlstr, defProtSch=None, allowFrag=None)

urlunparse(urltup)

urlparse.urljoin()

urljoin(baseurl, newurl,allowFrag=None)

20.2.3 urllib模块

urllib.urlopen()

urlopen(urlstr, postQueryData=None)

urllib.urlretrieve()

urlretrieve(urlstr, localfile=None, downloadStatusHook=None)

urllib.quote() and urllib,quote_plus()

urllib函数描述

urlopen(urlstr,postQurey-Data=None)

20.2.4 urllib2 模块

我们可以建立一个基础认证处理器(urllib2.HTTPBasicAuthHandler),同时在基

本URL或域上注册一个登陆密码,这就意味着我们在Web站点上定义了个安全区域,

一旦完成这些,你可以安装URL打开器,通过这个处理器打开所有的URL

另一个可选办法就是当浏览器提示的时候,输入用户名和密码,这样就发送了一个

带有适当用户请求的认证头

# vi urlopenAuth.py(问题)

-----------------------------------------

#!/usr/bin/env python

import urllib2

LOGIN = 'wesley'

PASSWD = "you'llNeverGuess"

URL = 'http://localhost'

def handler_version(url):

   from urlparse import urlparse as up

   hdlr = urllib2.HTTPBasicAuthHandler()

   hdlr.add_password('Archives', up(url)[1], LOGIN, PASSWD)

   opener = urllib2.build_opener(hdlr)

   urllib2.install_opener(opener)

   return url

def request_version(url):

   from base64 import encodestring

   req = urllib2.Request(url)

   b64str = encodestring('%s:%s' % (LOGIN, PASSWD))[:-1]

   req.add_header("Authorization", "Basic %s" % b64str)

   return req

for funcType in ('handler', 'request'):

   print '*** Using %s:' % funcType.upper()

   url = eval('%s_version')(URL)

   f = urllib2.urlopen(url)

   print f.readline()

   f.close()

-----------------------------------------

20.3 高级Web客户端

Web浏览器是基本的Web客户端,主要用来在Web上查询或者下载文件

高级Web客户端的一个例子就是网络爬虫,这些程序可以基于不同目的在因特网上

探索和下载页面:

1.为Google和Yahho这类大型搜索引擎建立索引

2.脱机浏览一将文档下载到本地,重新设定超链接,为本地浏览器创建镜像

3.下载并保存历史记录或框架

4.Web页的缓存,节省再次访问Web站点的下载时间

20.4 CGI:帮助Web服务器处理客户端数据

20.4.1 CGI介绍

CGI代表了在一个web服务器和能够处理用户表单,生成并返回动态HTML页的应用

程序间的交互

20.4.2 CGI应用程序

当一个CGI脚本开始执行时,它需要检索用户-支持表单,但这些数据必须要从web

客户端才可以获得,而不是从服务器或者硬盘上获得,所有的交互都将发生在Web

客户端,Web服务器端和CGI应用程序间

20.4.2 cgi模块

20.5 建立CGI应用程序

20.5.1 建立Web服务器

为了可以用Python进行CGI开发,首先需要安装一个Web服务器,将其配置成可以处

理Python CGI请求的模式,然后让你的Web服务器访问CGI脚本

1.可以下载安装apache及其Python CGI插件模块

2.利用Python自带的web服务器

# python -m CGIHTTPServer

---------------------------------

Serving HTTP on 0.0.0.0 port 8000 ...

---------------------------------

20.5.2 建立表单页

20.5.3 生成结果页

1.登陆一个非root账户,在当前目录下建立一个端口号为8000的web服务器

# cd ~

# pwd

---------------------

/home/python

---------------------

# mkdir web

# cd web

# python -m CGIHTTPServer

2.在启动这个服务器的目录下建立一个cgi-bin,并将Python CGI脚本放到该目录

# mkdir cgi-bin

# cd cgi-bin

# vi friends1.py

-------------------------

#!/usr/bin/env python

import cgi

reshtml = '''Content-Type: text/html\n

<HTML><HEAD><TITLE>

Friends CGI Demo (dynamic screen)

</TITLE></HEAD>

<BODY><H3>Friends list for: <I>%s</I></H3>

Your name is: <B>%s</B><P>

You have <B>%s</B> friends.

</BODY></HTML>'''

form = cgi.FieldStorage()

who = form['person'].value

howmany = form['howmany'].value

print reshtml % (who, who, howmany)

-------------------------

3.创建web表单:

这个HTML文件展示给用户一个空文档,含有用户名,和一系列可供用户选择的单选

按钮

# cd ..

# pwd

--------------------

/home/python/web

--------------------

# vi friends.htm

------------------------------------

<HTML>

<HEAD>

<TITLE>CGI Demo(static screen)</TITLE>

</HEAD>

<BODY><H3>Friends list for: <I>NEW USER</I></H3>

<FORM ACTION='cgi-bin/friends1.py'>

<B>Enter your Name:</B>

<INPUT TYPE='text' NAME=person VALUE='NEW USER' SIZE=15>

<P><B>How many friends do you have?</B></P>

<INPUT TYPE='radio' NAME=howmany VALUE='0' CHECKED> 0

<INPUT TYPE='radio' NAME=howmany VALUE='10'> 10

<INPUT TYPE='radio' NAME=howmany VALUE='25'> 25

<INPUT TYPE='radio' NAME=howmany VALUE='50'> 50

<INPUT TYPE='radio' NAME=howmany VALUE='100'> 100

<P><INPUT TYPE=submit></P>

</FORM>

</BODY>

</HTML>

------------------------------------

表单的变量是FieldStorage的实例,包含person和howmany 字段值,我们把值存入

Python的who和howmany变量,变量reshtml包含需要返回的HTML文本正文,还有一

些动态填好的字段,这些数据都是从表单中读入的

4.浏览器访问页面

http://localhost:8000/friends.htm

20.5.4 生成表单和结果页面

将friends.html和friends1.py合并成friends2.py,得到的脚本可以同时显示表

单和动态生成的HTML结果页面,同时可以巧妙的知道应该输出哪个页面

# vi friends2.py

---------------------------------

#!/usr/bin/env python

'''

$Id: friends2.py,v 1.1 2000/12/31 01:32:45 wesc Exp $

CGI demo

'''

import cgi

header = 'Content-Type: text/html\n\n'

formhtml = '''<HTML><HEAD><TITLE>Friends CGI Demo</TITLE></HEAD>

<BODY><H3>Friends list for: <I>NEW USER</I></H3>

<FORM ACTION="/cgi-bin/friends2.py">

<B>Enter your Name:</B>

<INPUT TYPE=hidden NAME=action VALUE=edit>

<INPUT TYPE=text NAME=person VALUE="" SIZE=15>

<P><B>How many friends do you have?</B>

%s

<P><INPUT TYPE=submit></FORM></BODY></HTML>'''

friendradio = '<INPUT TYPE=radio NAME=howmany VALUE="%s" %s> %s\n'

def showForm():

   friends = ''

   for i in [0, 10, 25, 50, 100]:

       checked = ''

       if i == 0:

           checked = 'CHECKED'

       friends = friends + friendradio % (str(i), checked, str(i))

   print header + formhtml % (friends)

reshtml = '''<HTML><HEAD><TITLE>Friends CGI Demo</TITLE></HEAD>

<BODY><H3>Friends list for: <I>%s</I></H3>

Your name is: <B>%s</B><P>

You have <B>%s</B> friends.

</BODY></HTML>'''

def doResults(who, howmany):

   # substitute in real name and number of friends and return

   print header + reshtml % (who, who, howmany)

# process() does all the work

def process():

   # initialize Data class object

   form = cgi.FieldStorage()

   # get user name

   if form.has_key('person'):

       who = form['person'].value

   else:

       who = 'NEW USER'

   # get name and number of friends

   if form.has_key('howmany'):

       howmany = form['howmany'].value

   else:

       howmany = 0

   # if editing, show results

   if form.has_key('action'):

       doResults(who, howmany)

   # otherwise, show form

   else:

       showForm()

# invoke if called directly

if __name__ == '__main__':

   process()

---------------------------------

20.5.5 全面交互的web站点

我们最后一个例子将会完成这个循环

用户在表单页中输入他/她的信息,然后我们处理这些数据,并输出一个结果页面

现在我们将会在结果页面上加个链接允许返回到表单页面,但是我们返回的是含

有用户输入信息的页面而不是一个空白页面,我们页面上加上了一些错误处理程

序,来展示它是如何实现的

例,通过加上返回输入信息的表单页面连接,我们实现了整个循环,并加上一些错

误验证,在用户没有选择任何单选按钮时,通知用户

# vi friends3.py

--------------------------------

#!/usr/bin/env python

'''

$Id: friends3.py,v 1.1 2000/12/31 01:32:45 wesc Exp $

Friends CGI demo

'''

import cgi

from urllib import quote_plus

from string import capwords

#from sys import stderr

#s = stderr.write

header = 'Content-Type: text/html\n\n'

url = 'http://192.168.102.88:8000/cgi-bin/friends3.py'

errhtml = '''<HTML><HEAD><TITLE>Friends CGI Demo</TITLE></HEAD>

<BODY><H3>ERROR</H3>

<B>%s</B><P>

<FORM><INPUT TYPE=button VALUE=Back ONCLICK="window.history.back

()"></FORM>

</BODY></HTML>'''

# showError() --> None

def showError(error_str):

   'showError() -- display error message'

   print header + errhtml % (error_str)

friendradio = '<INPUT TYPE=radio NAME=howmany VALUE="%s" %s> %s\n'

formhtml = '''<HTML><HEAD><TITLE>Friends CGI Demo</TITLE></HEAD>

<BODY><H3>Friends list for: <I>%s</I></H3>

<FORM ACTION="%s">

<B>Your Name:</B>

<INPUT TYPE=hidden NAME=action VALUE=edit>

<INPUT TYPE=text NAME=person VALUE="%s" SIZE=15>

<P><B>How many friends do you have?</B>

%s

<P><INPUT TYPE=submit></FORM></body></html>'''

# showForm() --> None

def showForm(who, howmany):

   'showForm() -- presents blank or data-filled form for new input'

   friends = ''

   for i in [0, 10, 25, 50, 100]:

       checked = ''

       if str(i) == howmany:

           checked = 'CHECKED'

       friends = friends + friendradio % (str(i), checked, str(i))

   print header + formhtml % (who, url, who, friends)

reshtml = '''<HTML><HEAD><TITLE>Friends CGI Demo</TITLE></HEAD>

<BODY><H3>Friends list for: <I>%s</I></H3>

Your name is: <B>%s</B><P>

You have <B>%s</B> friends.

<P>Click <a href="%s">here</a> to edit your data again.

</BODY></HTML>'''

# doResults() --> None

def doResults(who, howmany):

   'doResults() -- displays results with given form data'

   # substitute in real name and number of friends and return

   newurl = url + '?action=reedit&person=%s&howmany=%s' %

(quote_plus(who), howmany)

   print header + reshtml % (who, who, howmany, newurl)

# process() --> None

def process():

   'process() does all the work:  grabs user data and determines

routine to call'

   error = ''

   # initialize Data class object

   form = cgi.FieldStorage()

   #s('name: '+str(form.name)+'\n')

   #s('keys: '+str(form.keys())+'\n')

   #for i in form.keys():

           #s('item: '+str(form[i].name)+' has a value of '+str(form

[i].value)+' and is a ' + form[i].__class__.__name__ + '\n')

   # get user name

   if form.has_key('person'):

       who = capwords(form['person'].value)

   else:

       who = 'NEW USER'

   # get name and number of friends

   if form.has_key('howmany'):

       howmany = form['howmany'].value

   else:

       if form.has_key('action') and form['action'].value == 'edit':

           error = 'Please select the number of friends you have.'

       else:

           howmany = 0

   # no errors, either display form or present results

   if not error:

       # if editing the first time, show results

       if form.has_key('action') and form['action'].value !=

'reedit':

           doResults(who, howmany)

       # otherwise, show form

       else:

           showForm(who, howmany)

   # send error message back if error situation

   else:

       showError(error)

# invoke if called directly

if __name__ == '__main__':

   process()

--------------------------------

20.6 在CGI中使用Unide编码

例,简单Unicode CGI示例(uniCGI.py)

这个脚本输出到你web浏览器端的是Unicode字符串

# vi uniCGI.py

--------------------------------

#!/usr/bin/env python

CODEC = 'UTF-8'

UNICODE_HELLO = u'''

Hello!

\u00A1Hola!

\u4F60\u597D!

\u3053\u3093\u306B\u3061\u306F!

'''

print 'Content-Type: text/html; charset=%s\r' % CODEC

print '\r'

print '<HTML><HEAD><TITLE>Unicode CGI Demo</TITLE></HEAD>'

print '<BODY>'

print UNICODE_HELLO.encode(CODEC)

print '</BODY></HTML>'

--------------------------------

20.7 高级CGI

20.7.1 Mulitipart 表单提交和文件上传

20.7.2 多值字段

20.7.3 cookie

20.7.4 使用高级CGI

例,这个脚本有一个处理所有事情的主函数,AdvCGI,它有方法显示表单,错误或结

果页面,同事也可以从客户端(Web浏览器)读写cookie

# vi advcgi.py(问题)

----------------------------

#!/usr/bin/env python

from cgi import FieldStorage

from os import environ

from cStringIO import StringIO

from urllib import quote, unquote

from string import capwords, strip, split, join

class AdvCGI:

   header = 'Content-Type: text/html\n\n'

   url = '/py/advcgi.py'

   formhtml = '''<HTML><HEAD><TITLE>

Advanced CGI Demo</TITLE></HEAD>

<BODY><H2>Advanced CGI Demo Form</H2>

<FORM METHOD=post ACTION="%s" ENCTYPE="multipart/form-data">

<H3>My Cookie Setting</H3>

<LI> <CODE><B>CPPuser = %s</B></CODE>

<H3>Enter cookie value<BR>

<INPUT NAME=cookie value="%s"> (<I>optional</I>)</H3>

<H3>Enter your name<BR>

<INPUT NAME=person VALUE="%s"> (<I>required</I>)</H3>

<H3>What languages can you program in?

(<I>at least one required</I>)</H3>

%s

<H3>Enter file to upload</H3>

<INPUT TYPE=file NAME=upfile VALUE="%s" SIZE=45>

<P><INPUT TYPE=submit>

</FORM></BODY></HTML>'''

   langSet = ('Python', 'PERL', 'Java', 'C++', 'PHP',

                   'C', 'JavaScript')

   langItem = \

       '<INPUT TYPE=checkbox NAME=lang VALUE="%s"%s> %s\n'

   def getCPPCookies(self):                # reads cookies from

client

       if environ.has_key('HTTP_COOKIE'):

           for eachCookie in map(strip, \

                   split(environ['HTTP_COOKIE'], ';')):

               if len(eachCookie) > 6 and \

                       eachCookie[:3] == 'CPP':

                   tag = eachCookie[3:7]

                   try:

                       self.cookies[tag] = \

                           eval(unquote(eachCookie[8:]))

                   except (NameError, SyntaxError):

                       self.cookies[tag] = \

                           unquote(eachCookie[8:])

       else:

           self.cookies['info'] = self.cookies['user'] = ''

       if self.cookies['info'] != '':

           self.who, langStr, self.fn = \

               split(self.cookies['info'], ':')

           self.langs = split(langStr, ',')

       else:

           self.who = self.fn = ''

           self.langs = ['Python']

   def showForm(self):                        # show fill-out form

       self.getCPPCookies()

       langStr = ''

       for eachLang in AdvCGI.langSet:

           if eachLang in self.langs:

               langStr = langStr + AdvCGI.langItem % \

                   (eachLang, ' CHECKED', eachLang)

           else:

               langStr = langStr + AdvCGI.langItem % \

                   (eachLang, '', eachLang)

       if not self.cookies.has_key('user') or \

               self.cookies['user'] == '':

           cookieStatus = '<I>(cookie has not been set yet)</I>'

           userCook = ''

       else:

           userCook = cookieStatus = self.cookies['user']

       print AdvCGI.header + AdvCGI.formhtml % (AdvCGI.url,

           cookieStatus, userCook, self.who, langStr, self.fn)

   errhtml = '''<HTML><HEAD><TITLE>

Advanced CGI Demo</TITLE></HEAD>

<BODY><H3>ERROR</H3>

<B>%s</B><P>

<FORM><INPUT TYPE=button VALUE=Back

ONCLICK="window.history.back()"></FORM>

</BODY></HTML>'''

   def showError(self):

       print AdvCGI.header + AdvCGI.errhtml % (self.error)

   reshtml = '''<HTML><HEAD><TITLE>

Advanced CGI Demo</TITLE></HEAD>

<BODY><H2>Your Uploaded Data</H2>

<H3>Your cookie value is: <B>%s</B></H3>

<H3>Your name is: <B>%s</B></H3>

<H3>You can program in the following languages:</H3>

<UL>%s</UL>

<H3>Your uploaded file...<BR>

Name: <I>%s</I><BR>

Contents:</H3>

<PRE>%s</PRE>

Click <A HREF="%s"><B>here</B></A> to return to form.

</BODY></HTML>'''

   def setCPPCookies(self):

       for eachCookie in self.cookies.keys():

           print 'Set-Cookie: CPP%s=%s; path=/' % \

               (eachCookie, quote(self.cookies[eachCookie]))

   def doResults(self):

       MAXBYTES = 1024

       langlist = ''

       for eachLang in self.langs:

           langlist = langlist + '<LI>%s<BR>' % eachLang

       filedata = ''

       while len(filedata) < MAXBYTES:        # read file chunks

           data = self.fp.readline()

           if data == '': break

           filedata = filedata + data

       else:                                # truncate if too long

           filedata = filedata + \

               '... <B><I>(file truncated due to size)</I></B>'

       self.fp.close()

       if filedata == '':

           filedata = \

               '<B><I>(file upload error or file not given)</I></B>'

       filename = self.fn

       if not self.cookies.has_key('user') or \

               self.cookies['user'] == '':

           cookieStatus = '<I>(cookie has not been set yet)</I>'

           userCook = ''

       else:

           userCook = cookieStatus = self.cookies['user']

       self.cookies['info'] = join([self.who, \

           join(self.langs, ','), filename], ':')

       self.setCPPCookies()

       print AdvCGI.header + AdvCGI.reshtml % \

           (cookieStatus, self.who, langlist,

           filename, filedata, AdvCGI.url)

   def go(self):                # determine which page to return

       self.cookies = {}

       self.error = ''

       form = FieldStorage()

       if form.keys() == []:

           self.showForm()

           return

       if form.has_key('person'):

           self.who = capwords(strip(form['person'].value))

           if self.who == '':

               self.error = 'Your name is required. (blank)'

       else:

           self.error = 'Your name is required. (missing)'

       if form.has_key('cookie'):

           self.cookies['user'] = unquote(strip( \

               form['cookie'].value))

       else:

           self.cookies['user'] = ''

       self.langs = []

       if form.has_key('lang'):

           langdata = form['lang']

           if type(langdata) == type([]):

               for eachLang in langdata:

                   self.langs.append(eachLang.value)

           else:

               self.langs.append(langdata.value)

       else:

           self.error = 'At least one language required.'

       if form.has_key('upfile'):

           upfile = form["upfile"]

           self.fn = upfile.filename or ''

           if upfile.file:

               self.fp = upfile.file

           else:

               self.fp = StringIO('(no data)')

       else:

           self.fp = StringIO('(no file)')

           self.fn = ''

       if not self.error:

           self.doResults()

       else:

           self.showError()

if __name__ == '__main__':

   page = AdvCGI()

   page.go()

----------------------------

20.8 Web(HTTP)服务器

20.8.1 用Python建立Web服务器

例,这个简单的Web服务器可以读取GET请求,获取Web页面并将其返回给客户端,它

通过使用BaseHTTPServer的BaseHTTPRequestHandler处理器执行do_GET()方法来

处理GET请求

# vi myhttpd.py

----------------------------------

#!/usr/bin/env python

from os import curdir, sep

from BaseHTTPServer import \

   BaseHTTPRequestHandler, HTTPServer

class MyHandler(BaseHTTPRequestHandler):

   def do_GET(self):

       try:

           f = open(curdir + sep + self.path)

           self.send_response(200)

           self.send_header('Content-type',

'text/html')

           self.end_headers()

           self.wfile.write(f.read())

           f.close()

       except IOError:

           self.send_error(404,

'File Not Found: %s' % self.path)

def main():

   try:

       server = HTTPServer(('', 80), MyHandler)

       print 'Welcome to the machine...'

print 'Press ^C once or twice to quit'

       server.serve_forever()

   except KeyboardInterrupt:

       print '^C received, shutting down server'

       server.socket.close()

if __name__ == '__main__':

   main()

----------------------------------

20.9 相关模块

........

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