Python笔记之网络编程

1，学习这部分，应先了解一下OSI 7层模型，TCP/IP四层，Socket套接字等网络相关知识点。

Python网络库，urllib，urllib2，后者功能更强大一些。

import urllib2import urllibresponse = urllib2.urlopen('http://www.baidu.com') #获取百度首页的代码，打开远程文件urllib.urlretrieve(‘http://www.baidu.com','baidu_index.html')     #下载文件并保存到本地html = response.read()print html

还有smtplib，email，cgi，httplib，ftplib，Cookie等其他模块，现用现查即可。

---

2，socket模块

服务器端Demo

import sockets = socket.socket() #host = socket.gethostname()port = 1234s.bind((host,port))s.listen(5)while True:     c,addr = s.accept()     print 'client link from:',addr     c.send('Hello, client. This is server')     c.close()

SocketServer模块，简化服务器端编程。

from SocketServer import TCPServer,StreamRequestHandlerclass Handler(StreamRequestHandler):def handle(self):     #处理放在handle方法中addr = self.request.getpeername()print 'get link from:',addrself.wfile.write('welcome, link succeed')server = TCPServer(('',1234),Handler)server.serve_forever()#begin to listen and handle link

#运行结果bowen:~ bowen$ vimSocketServer_server.pybowen:~ bowen$ python SocketServer_server.pyget link from: ('192.168.42.184', 49533)

客户端Demo

import sockets = socket.socket()host = socket.gethostname()port = 1234s.connect((host,port))     #连接服务器print s.recv(1024)s.close()

服务器与客户端通信Demo

bowen:Python bowen$ cat server.pyimport socketsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)#create Socketsock.bind(('localhost',8001))#bind ip and portsock.listen(5)#start listeningwhile True:conn,addr = sock.accept()print 'link from:',addrtry:conn.settimeout(5)buff = conn.recv(1024)if buff == '1':conn.send('welcome to server')#send msg to clientelse:conn.send('Plead go out')except socket.timeout:print 'time out exception'conn.close()#close linkbowen:Python bowen$ cat client.pyimport socketimport timesock = socket.socket()sock.connect(('localhost',8001))time.sleep(2)sock.send('1')print sock.recv(1024)#recv msg from serversock.close()

#运行结果bowen:~ bowen$ vimSocketServer_server.pybowen:~ bowen$ python SocketServer_server.pyget link from: ('192.168.42.184', 49533)

---

3，异步通信

1，分叉方式（ForkingMixIn）；Server类提供了多连接处理，和数据传输服务。

from SocketServer import TCPServer,ForkingMixIn,StreamRequestHandlerclass Server(ForkingMixIn, TCPServer):passclass Handler(StreamRequestHandler):def handle(self):addr = self.request.getpeername()print 'get link from:',addrself.wfile.write('many links by fork')if __name__ == '__main__':server = Server(('localhost',1234),Handler)server.serve_forever()

---

2，线程方式（ThreadingMixIn）；与分叉处理类似，区别仅在于Server继承的是ThreadingMixIN

from SocketServer import TCPServer,ThreadingMixIn,StreamRequestHandlerclass Server(ThreadingMixIn, TCPServer):passclass Handler(StreamRequestHandler):def handle(self):addr = self.request.getpeername()print 'get link from:',addrself.wfile.write('many links in Thread way')if __name__ == '__main__':server = Server(('localhost',1234),Handler)server.serve_forever()

---

3，异步I／O方式，select（）方法用于对指定的文件描述符进行监视，并在描述符改变时做出响应。还有poll（）方法也可实现。

import socket, selects = socket.socket()s.bind(('localhost',1234))s.listen(5)inputs = [s]#store socket reqwhile True:rs,ws,es = select.select(inputs,[],[])#use select()for r in rs:if r is s:conn,addr = s.accept()print 'get link form:',addrinputs.append(conn)#put socket conn  into inputselse:try:    data = r.recv(1024)    disconnected = not dataexcept socket.error:    disconnected = Trueif disconnected:    print r.getpeername(),' disconnected'    inputs.remove(r)else:<span style="white-space:pre"></span>    print data