python网络基础学习笔记：一个简单的server

#! /usr/bin/env pythonimport socket, syshost = 'localhost'port = 54321s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)s.bind((host, port))s.listen(1)print "Server is running in port %d" % portwhile 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()