Python 是一种极具可读性和通用性的编程语言。Python 易于设置，并且是用相对直接的风格来编写，对错误会提供即时反馈，对初学者而言是个很好的选择。
Python 是一种多范式语言，也就是说，它支持多种编程风格，包括脚本和面向对象，这使得它适用于通用目的。

Python项目练习一：即时标记

这个项目分为四个模块：

分析器：负责读取文本，管理其他的类

规则：检测文本块的类型（标题，列表等），使用相对应的规则

过滤器：处理一些内嵌元素，比如

处理程序：为文本块添加标记

目的就是要将一段文本根据文本的格式转换成HTML

Python项目练习二：画幅好画

这是《python基础教程》中的第二个项目，关于python操作PDF

涉及到的知识点

1、urllib的使用

2、reportlab库的使用

这个例子着实很简单，不过我发现在python里面可以直接在数组［］里面写for循环，真是越用越方便。

下面是代码：

Python项目练习三：新闻聚合

新闻聚合，现在很少见的一类应用，至少我从来没有用过，又叫做Usenet。
这个程序的主要功能是用来从指定的来源（这里是Usenet新闻组）收集信息，然后讲这些信息保存到指定的目的文件中（这里使用了两种形式：纯文本和html文件）。

from nntplib import NNTP
from time import strftime,time,localtime
from email import message_from_string
from urllib import urlopen
import textwrap
import re
day = 24*60*60
def wrap(string,max=70):
    '''
    '''
    return '\n'.join(textwrap.wrap(string)) + '\n'
class NewsAgent:
    '''
    '''
    def __init__(self):
        self.sources = []
        self.destinations = []
    def addSource(self,source):
        self.sources.append(source)
    def addDestination(self,dest):
        self.destinations.append(dest)
    def distribute(self):
        items = []
        for source in self.sources:
            items.extend(source.getItems())
        for dest in self.destinations:
            dest.receiveItems(items)
class NewsItem:
    def __init__(self,title,body):
        self.title = title
        self.body = body
class NNTPSource:
    def __init__(self,servername,group,window):
        self.servername = servername
        self.group = group
        self.window = window
    def getItems(self):
        start = localtime(time() - self.window*day)
        date = strftime('%y%m%d',start)
        hour = strftime('%H%M%S',start)
        server = NNTP(self.servername)
        ids = server.newnews(self.group,date,hour)[1]
        for id in ids:
            lines = server.article(id)[3]
            message = message_from_string('\n'.join(lines))
            title = message['subject']
            body = message.get_payload()
            if message.is_multipart():
                body = body[0]
            yield NewsItem(title,body)
        server.quit()
class SimpleWebSource:
    def __init__(self,url,titlePattern,bodyPattern):
        self.url = url
        self.titlePattern = re.compile(titlePattern)
        self.bodyPattern = re.compile(bodyPattern)
    def getItems(self):
        text = urlopen(self.url).read()
        titles = self.titlePattern.findall(text)
        bodies = self.bodyPattern.findall(text)
        for title.body in zip(titles,bodies):
            yield NewsItem(title,wrap(body))
class PlainDestination:
    def receiveItems(self,items):
        for item in items:
            print item.title
            print '-'*len(item.title)
            print item.body
class HTMLDestination:
    def __init__(self,filename):
        self.filename = filename
    def receiveItems(self,items):
        out = open(self.filename,'w')
        print >> out,'''
        
        
         
        
        
        
Today's News
        '''
        print >> out, '
'
        id = 0
        for item in items:
            id += 1
            print >> out, '
%s
' % (id,item.title)
        print >> out, '
'
        id = 0
        for item in items:
            id += 1
            print >> out, '
%s
' % (id,item.title)
            print >> out, '
%s
' % item.body
        print >> out, '''
        
        
        '''
def runDefaultSetup():
    agent = NewsAgent()
    bbc_url = 'http://news.bbc.co.uk/text_only.stm'
    bbc_title = r'(?s)a href="[^" rel="external nofollow" ]*">\s*\s*(.*?)\s*'
    bbc_body = r'(?s)\s*
\s*(.*?)\s*<'
    bbc = SimpleWebSource(bbc_url, bbc_title, bbc_body)
    agent.addSource(bbc)
    clpa_server = 'news2.neva.ru'
    clpa_group = 'alt.sex.telephone'
    clpa_window = 1
    clpa = NNTPSource(clpa_server,clpa_group,clpa_window)
    agent.addSource(clpa)
    agent.addDestination(PlainDestination())
    agent.addDestination(HTMLDestination('news.html'))
    agent.distribute()
if __name__ == '__main__':
    runDefaultSetup()from nntplib import NNTP
from time import strftime,time,localtime
from email import message_from_string
from urllib import urlopen
import textwrap
import re
day = 24*60*60
def wrap(string,max=70):
    '''
    '''
    return '\n'.join(textwrap.wrap(string)) + '\n'
class NewsAgent:
    '''
    '''
    def __init__(self):
        self.sources = []
        self.destinations = []
    def addSource(self,source):
        self.sources.append(source)
    def addDestination(self,dest):
        self.destinations.append(dest)
    def distribute(self):
        items = []
        for source in self.sources:
            items.extend(source.getItems())
        for dest in self.destinations:
            dest.receiveItems(items)
class NewsItem:
    def __init__(self,title,body):
        self.title = title
        self.body = body
class NNTPSource:
    def __init__(self,servername,group,window):
        self.servername = servername
        self.group = group
        self.window = window
    def getItems(self):
        start = localtime(time() - self.window*day)
        date = strftime('%y%m%d',start)
        hour = strftime('%H%M%S',start)
        server = NNTP(self.servername)
        ids = server.newnews(self.group,date,hour)[1]
        for id in ids:
            lines = server.article(id)[3]
            message = message_from_string('\n'.join(lines))
            title = message['subject']
            body = message.get_payload()
            if message.is_multipart():
                body = body[0]
            yield NewsItem(title,body)
        server.quit()
class SimpleWebSource:
    def __init__(self,url,titlePattern,bodyPattern):
        self.url = url
        self.titlePattern = re.compile(titlePattern)
        self.bodyPattern = re.compile(bodyPattern)
    def getItems(self):
        text = urlopen(self.url).read()
        titles = self.titlePattern.findall(text)
        bodies = self.bodyPattern.findall(text)
        for title.body in zip(titles,bodies):
            yield NewsItem(title,wrap(body))
class PlainDestination:
    def receiveItems(self,items):
        for item in items:
            print item.title
            print '-'*len(item.title)
            print item.body
class HTMLDestination:
    def __init__(self,filename):
        self.filename = filename
    def receiveItems(self,items):
        out = open(self.filename,'w')
        print >> out,'''
        
        
         
        
        
        
Today's News
        '''
        print >> out, '
'
        id = 0
        for item in items:
            id += 1
            print >> out, '
%s
' % (id,item.title)
        print >> out, '
'
        id = 0
        for item in items:
            id += 1
            print >> out, '
%s
' % (id,item.title)
            print >> out, '
%s
' % item.body
        print >> out, '''
        
        
        '''
def runDefaultSetup():
    agent = NewsAgent()
    bbc_url = 'http://news.bbc.co.uk/text_only.stm'
    bbc_title = r'(?s)a href="[^" rel="external nofollow" ]*">\s*\s*(.*?)\s*'
    bbc_body = r'(?s)\s*
\s*(.*?)\s*<'
    bbc = SimpleWebSource(bbc_url, bbc_title, bbc_body)
    agent.addSource(bbc)
    clpa_server = 'news2.neva.ru'
    clpa_group = 'alt.sex.telephone'
    clpa_window = 1
    clpa = NNTPSource(clpa_server,clpa_group,clpa_window)
    agent.addSource(clpa)
    agent.addDestination(PlainDestination())
    agent.addDestination(HTMLDestination('news.html'))
    agent.distribute()
if __name__ == '__main__':
    runDefaultSetup()
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这个程序，首先从整体上进行分析，重点部分在于NewsAgent，它的作用是存储新闻来源，存储目标地址，然后在分别调用来源服务器（NNTPSource以及SimpleWebSource）以及写新闻的类（PlainDestination和HTMLDestination）。所以从这里也看的出，NNTPSource是专门用来获取新闻服务器上的信息的，SimpleWebSource是获取一个url上的数据的。而PlainDestination和HTMLDestination的作用很明显，前者是用来输出获取到的内容到终端的，后者是写数据到html文件中的。

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