python网络编程——简单例子

客户端（client.py）

import socket
import sys

port = 70
host = sys.argv[1]
filename = sys.argv[2]

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
fd = s.makefile("rw", 0)
fd.write(filename + "\n")
for line in fd.readlines():
    sys.stdout.write(line)

程序通过socket.socket()建立一个Socket，参数告诉系统需要一个Internet Socket进行TCP通信。接着程序链接远程的主机名，并提供文件名。最后获得响应后在屏幕上打印出来。

测试

python client.py quux.org /

显示

iWelcome to gopher at quux.org!	fake	(NULL)	0
i	fake	(NULL)	0
iThis server has a lot of information of historic interest,	fake	(NULL)	0
ifunny, or just plain entertaining -- all presented in Gopher.	fake	(NULL)	0
iThere are many mirrors here of rare or valuable files with the	fake	(NULL)	0
iaim to preserve them in case their host disappears.  PLEASE READ	fake	(NULL)	0
i"About This Server" FOR IMPORTANT NOTES AND LEGAL INFORMATION.	fake	(NULL)	0
i	fake	(NULL)	0
0About This Server	/About This Server.txt	gopher.quux.org	70	+
1Archives	/Archives	gopher.quux.org	70	+
1Books	/Books	gopher.quux.org	70	+
1Communication	/Communication	gopher.quux.org	70	+
iThis directory contains the entire text of the book	fake	(NULL)	0
i"We the Media: Grassroots Journalism by the People, for the People"	fake	(NULL)	0
iby Dan Gillmor in various formats.	fake	(NULL)	0
i	fake	(NULL)	0
iFeel free to download and enjoy.	fake	(NULL)	0
1Computers	/Computers	gopher.quux.org	70	+
1Current Issues and Events (Updated Apr. 23, 2002)	/Current	gopher.quux.org	70	+
1Development Projects	/devel	gopher.quux.org	70	+
0Gopher's 10th Anniversary	/3.0.0.txt	gopher.quux.org	70
1Government, Politics, Law, and Conflict	/Government	gopher.quux.org	70	+
0How To Help	/How To Help.txt	gopher.quux.org	70	+
1Humor and Fun	/Humor and Fun	gopher.quux.org	70	+
1Index to Quux.Org	/Archives/index	gopher.quux.org	70
1Internet	/Internet	gopher.quux.org	70	+
1Other Gopher Servers	/Software/Gopher/servers	gopher.quux.org	70
1People	/People	gopher.quux.org	70	+
1Reference	/Reference	gopher.quux.org	70	+
1Software and Downloads	/Software	gopher.quux.org	70	+
1The Gopher Project	/Software/Gopher	gopher.quux.org	70
0What's New	/whatsnew.txt	gopher.quux.org	70	+　

服务端（server.py）

# coding: utf-8
import socket
host = ''
port = 51421
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))
s.listen(1)               #每次最多只有一个等候处理
print "Server is running on port %d; press Ctrl-C to terminate." %port

while 1:
    clientsock, clientaddr = s.accept()
    clientfile = clientsock.makefile('rw', 0)
    clientfile.write("Welcome, " + str(clientaddr) + "\n")
    clientfile.write("Please enter a string: ")
    line = clientfile.readline().strip()
    clientfile.write("You entered %d characters. \n" %len(line))
    clientfile.close()
    clientsock.close()

建立一个socket，设置成可复用的（reusable），绑定端口号51421（可选大于1024的任一值），调用listen（）函数，开始等待来自客户端的请求，同时设定最多只有一个等候处理的链接。

主循环对a.accept（）函数调用开始，程序连接一个客户端后立马停止，接收用户的输入。

运行一个例子

首先运行server.py

python server.py

另开一个终端，连接localhost的51421端口。　

jihite@ubuntu:~/web$ telnet localhost 51421
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Welcome, ('127.0.0.1', 59853)
Please enter a string: mm
You entered 2 characters.
Connection closed by foreign host.