Python程序练习(1)
from asyncio.constants import ACCEPT_RETRY_DELAY
from urllib.request import urlopen
webpage = urlopen('http://www.python.org')
#假设要提取刚才所打开网页中链接About的相对URL，可使用正则表达式
import re
text = webpage.read()
m = re.search(b'<a href="([^"]+)" .*?>about</a>',text,re.IGNORECASE)
m.group(1)
'/about/'
#如果要给下载的副本指定文件名，可通过第二个参数来提供。
urlretrieve('http://www.python.org','C:\\python_webpage.html')
#代码清单14-3 基于SocketServer的极简服务器
from socketserver import TCPServer, StreamRequestHandler
class Handler(StreamRequestHandler):
def handle(self):
addr = self.request.getpeername()
print('Got connection from',addr)
self.wfile.write('Thank you for connecting')
server = TCPServer(('',1234),Handler)
server.serve_forever()
#代码清单14-4 分叉服务器
from socketserver import TCPServer,ForkingMixIN,StreamRequestHandler
class Server(ForkingMixIN,TCPServer):pass
class Handler(StreamRequestHandler):
def handle(self):
addr = self.request.getpeername()
print('Got connection from',addr)
self wfile.write('Thank you for connecting')
server = Server(('',1234),Handler)
server.serve_forever()
#代码清单14-5 线程化服务器
from socketserver import TCPServer,ThreadingMixIN,StreamRequestHandler
class Server(ThreadingMixIN,TCPServer):pass
class Handler(StreamRequestHandler):
def handle(self):
addr = self.request.getpeername()
print('Got connection from',addr)
self.wfile.write('Thank you for connecting')
server = Server(('',1234),Handler)
server.serve_forever()
#代码清单14-6 使用select的简单服务器
import socket,select
s = socket.socket()
host = socket.gethostname()
port = 1234
s.bind((host,port))
s.listen(5)
inputs = [s]
while True:
rs, ws, es = select.select(inputs,[],[])
for r in rs:
if r is s:
c,addr = s.accept()
print('Got connection from',addr)
inputs.append(c)
else:
try:
data = r.recv(1024)
disconnected = not data
except socket.error:
disconnected = True
if disconnected:
print(r.getpeername(),'disconnected')
inputs.remove(r)
else:
print(data)
#代码清单14-7 使用poll的简单服务器
import socket,select
s = socket.socket()
host = socket.gethostname()
port = 1234
s.bind((host,port))
fdmap = {s.fileno():s}
s.listen(5)
p = select.poll()
p.register(s)
while True:
events = p.poll()
for fd,event in events:
if fd in fdmap:
c, addr = s.accept()
print('Got connection from',addr)
p.register(c)
fdmap[c.fileno()] = c
elif event & select.POLLIN:
data = fdmap[fd].recv(1024)
if not data:# 没有数据 --连接已关闭
print(fdmap[fd].getpeername(),'disconnected')
p.unregister(fd)
del fadmap[fd]
else:
print(data)
#代码清单14-8 使用Twisted创建的简单服务器
from twisted.internet import reactor
from twisted.internet.protocol import Protocol,Factory
class SimpleLogger(Protocol):
def connectionMade(self):
print('Got connection from',self.transport.client)
def connectionLost(self,reason):
print(self.transport.client,'disconnected')
def dataReceived(self,data):
print(data)
factory = Factory()
factory.protocol = SimpleLogger
reactor.listenTCP(1234,factory)
reactor.run()
#代码清单14-9 使用协议LineReceiver改进后的日志服务器
from twisted.internet import reactor
from twisted.internet.protocol import Factory
from twisted.protocols.basic import LineReceiver
class SimpleLogger(LineReceiver):
def connectionMade(self):
print('Got connection from',self.transport.client)
def connectionLost(self,reason):
print(self.transport.client,'disconnected')
def lineReceived(self,line):
print(line)
factory = Factory()
factory.protocol = SimpleLogger
reactor.listenTCP(1234,factory)
reactor.run()
#代码清单15-1 简单的屏幕抓取程序
from urllib.request import urlopen
import re
p = re.compile('<a href ="(/jobs/\\d+)/">(.*?)</a>')
text = urlopen('http://python.org/jobs').read().decode()
for url,name in p.findall(text):
print('{} ({})'.format(name,url))
'''
<h1>Pet Shop
<h2>Complaints</h3>
<p>There is <b>no <i>way</b> at all</i> we can accept returned parrots.
<h1><i>Dead Pets</h1>
<p>Our pets may tend to rest at times,but rarely die within the warrantly period.
<i><h2>News</h2></i>
<p>We have just received <b>a really nice parrot.
<p>It's really nice.</b>
<h3><hr>The Norwegian Blue</h3>
<h4>Plumage and <hr>pining behavior</h4>
<a href="#norwegain-blue">More information<a>
<p>Features:
<body>
<li>Beautiful plumage
'''
#下面是Tidy修复后的版本：
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<h1>Pet Shop</h1>
<h2>Complaints</h2>
<p>There is <b>no <i>way</i></b> <i>at all</i> we can accept returned parrots.</p>
<h1><i>Dead Pets</i></h1>
<p><i>Our pets may tend to rest at times,but rarely die within the warrantly period.</i></p>
<h2><i>News</i></h2>
<p>We have just received <b>a really nice parrot.</b></p>
<p><b>It's really nice.</b></p>
<hr>
<h3>The Norwegain Blue</h3>
<h4>Plumage and</h4>
<hr>
<h4>pining behavior</h4>
<a href="#norwegain-blue">More information</a>
<p>Features:</p>
<ul>
<li>Beautiful plumage</li>
</ul>
</body>
</html>
#例如，假设你有一个混乱的HTML文件（messy.html），且在执行路径中包含命令行版Tidy，下面的程序将对这个文件运行Tidy并将结果打印出来：
from subprocess import Popen,PIPE
text = open('messy.html').read()
tidy = Popen('tidy',stdin=PIPE,stdout=PIPE,stderr=PIPE)
tidy.stdin.write(text.encode())
tidy.stdin.close()
print(tidy.stdout.read().decode())
#代码清单15-2 使用模块HTMLParser的屏幕抓取程序
from urllib.request import urlopen
from html.parser import HTMLParser
def isjob(url):
try:
a,b,c,d=url.split('/')
except ValueError:
return False
return a==d==''and b=='jobs' and c.isdigit()
class Scraper(HTMLParser):
in_link = False
def handle_starttag(self,tag,attrs):
attrs = dict(attrs)
url = attrs.get('href','')
if tag == 'a' and isjob(url):
self.url=url
self.in_link=True
self.chunks=[]
def handle_data(self,data):
if self.in_link:
self.chunks.append(data)
def handle_endtag(self,tag):
if tag == 'a' and self.in_link:
print('{} ({})'.format(''.join(self.chunks),self.url))
self.in_link=False
text = urlopen('http://python.org/jobs').read().decode()
parser = Scraper()
parser.feed(text)
parser.close()
#代码清单15-3 使用Beautiful Soup的屏幕抓取程序
from urllib.request import urlopen
from bs4 import BeautifulSoup
text = urlopen('http://python.org/jobs').read()
soup = BeautifulSoup(text,'html.parser')
jobs = set()
for job in soup.body.section('h2'):
jobs.add('{} ({})'.format(job.a.string,job.a['href']))
print('\n'.join(sorted(jobs,key=str.lower)))
#代码清单15-4 简单的CGI脚本
#!/usr/bin/env python
print('Content-type:text/plain')
print()## 打印一个空行，以结束首部
print('Hello,world!')
#代码清单15-5 显示栈跟踪的CGI脚本（faulty.cgi）
#!/usr/bin/env python
import cgitb;cgitb.enable()
print('Content-type:text/html\n')
print(1/0)
print('Hello,world!')
#代码清单15-6 从FieldStorage中获取单个值的CGI脚本（simple2.cgi）
#!/usr/bin/env python
import cgi
from = cgi.FieldStorage()
name = form.getvalue('name','world')
print('Content-type:text/plain\n')
print('Hello,{}!'.format(name))
#代码清单15-7 包含HTML表单的问候脚本（simple3.cgi）
#!/usr/bin/env python
import cgi
form = cgi.FieldStorage()
name = form.getvalue('name','world')
print("""Content-type:text/html
<html>
<head>
<title>Greeting Page</title>
</head>
<body>
<h1>Hello,{}!</h1>
<form action = 'simple3.cgi'>
Change name <input type = 'text' name='name' />
<input type = 'submit' />
</form>
</body>
</html>
""".format(name))
'''
在这个脚本开头，与以前一样获取CGI参数name，并将默认值设置为'world'。如果在浏览器
中打开这个脚本时没有提交任何值，将使用默认值。
接下来，打印了一个简单的HTML页面，其中的标题包含参数name的值。另外，这个页面还
包含一个HTML表单，该表单的属性action被设置为脚本的名称（simple3.cgi）。这意味着提交表
单后，将再次运行这个脚本。这个表单只包含一个输入元素——名为name的文本框。因此，如果
你在文本框中输入新名字并提交表单，标题将发生变化，因为现在参数name包含值。
'''
#https://wiki.python.org/moin/WebFrameworks
#JSON，http://www.json.org
#代码清单16-1 简单的测试程序
from area import rect_area
height = 3
width = 4
correct_answer = 12
answer = rect_area(height,width)
if answer == correct_answer:
print('Test passed')
else:
print('Test failed')
#代码清单16-3 使用模块subprocess调用外部检查器
import unittest,my_math
from subprocess import Popen,PIPE
class ProductTestCase(unittest.TestCase):
#在这里插入以前的测试
def test_with_PyChecker(self):
cmd = 'pychecker','-Q',my_math.__file__.rstrip('c')
pychecker = Popen(cmd,stdout=PIPE,stderr=PIPE)
self.assertEqual(pychecker.stdout.read(),'')
def test_with_PyLint(self):
cmd = 'pylint','-rn','my_math'
pylint = Popen(cmd,stdout=PIPE,stderr=PIPE)
self.assertEqual(pylint.stdout.read(),'')
if __name__ =='__main__':unittest.main()
#代码清单17-1 一个简单的Java类（JythonTest.java）
public class JythonTest {
public void greeting(){
System.out.println("Hello,world!");
}
}
#$ javac JythonTest.java
#代码清单17-2 一个简单的C#类（IronPythonTest.cs）
using System;
namespace FePyTest{
public class IronPythonTest{
public void greeting(){
Console.WriteLine("Hello,world");
}
}
}
#对于Microsoft .NET，命令如下：
#csc.exe /t:library IronPythonTest.cs
#《C语言入门经典（第5版）》 《C程序设计语言（第2版）》
#NumPy（http://numpy.org）
#一个简单的检测回文的C语言函数（palindrome.c）
#include <string.h>
int is_palindrome(char *text){
int i, n=strlen(text);
for(i=0;I<=n/2;++i){
if(text[i] != text[n-i-1]) return 0;
}
return 1;
}
#代码清单17-4 检测回文的Python函数
def is_palindrome(text):
n = len(text)
for i in range(len(text) // 2):
if text[i] != text[n-i-1