python network programming common codes

Server-side code:

# -*- coding: cp936 -*-
import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)#初始化socket
sock.bind(("127.0.0.1", 8001))#绑定本机地址，8001端口
sock.listen(5)#等待客户连接
while True:
  print "waiting client connection..."
  connection,address = sock.accept()#接收客户连接请求
  print "a client have connected..."
  while True:
    try:
      connection.settimeout(5) #设置超时时间
      buf = connection.recv(1024) #接收数据
      if buf == "1":
        connection.send("you have send me 1!welcome to server!")
      elif buf=="2":
        connection.send("you have send me 2!I have recv!")
      elif buf=="3":
        connection.send("close the connection!")
        break
      else:
        connection.send("unknow command!")
    except socket.timeout:
      print "time out"
  connection.close()
  print "a client exit..."

Client-side code:

import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(("127.0.0.1", 8001))
import time
time.sleep(2)
while True:
  data=raw_input("input command:");
  sock.send(data)
  print sock.recv(1024)
  if data=="3":
    break
sock.close()

1. First open two IDLEs and open the server-side and client-side codes respectively.
2.F5 runs the server-side code, and waiting client connection will appear...
3.F5 runs the client-side code, and input command: appears;
4.At this time, the server and client are connected. Now, normal communication is possible, as shown in the figure:

5. An error will occur when running the server-side code again. At this time, you can use the task manager to change the pythonw After the .exe process ends, reopen it and compile it!

Client:

import socket
s=socket.socket()
host = socket.gethostname()
port = 1234
s.connect((host, port))
print s.recv(1024)

Server:

import socket
s = socket.socket()
host = socket.gethostname()
port = 1234
s.bind((host, port))

s.listen(5)
while True:
 c, addr = s.accept()
 print 'Got connection from', addr
 c.send('Thank you for connecting')
 c.close()

http programming

from urllib import urlopen
webpage = urlopen('http://www.python.org')

plus regular expression

import re
text = webpage.read()
m = re.search(&#39;<a href="([^"]+)" .*?>about</a>&#39;, text, re.IGNORECASE)
m.group(1)

urllib
urllib2

An example of a small server based on SocketServer:

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()

Using SocketServer for forking and threading
Forking Server:

from SocketServer import TCPServer,ForkingMinIn, StreamRequestHandler
class Server(ForkingMinIn, TCPServer):pass
class Handler(StreamRequestHandler):
 def handle(self):
  addr = self.request.getpeername()
  print 'Got connection from',addr
  self.wfile.write('Thank you for connection')
server = Server(('',1234),Handler)
server.serve_forever()

Thread Server:

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()

Asynchronous I/O with select and pool
select service:

import socket, select
s = socket.socket()
host = socket.gethostname()
prot = 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

pool server:

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:
    print fdmap[fd].getpeername(),'disconnected'
    p.unregister(fd)
    del fdmap[fd]
  else:
   print data

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