【Socket编程】篇七之Python实现Socket

一年前使用过C来实现Socket，如今见识了脚本的便利之后，我来尝试用Python再次实现一遍。

UDP：

客户端：

import socket
serverName = "127.0.0.1"
serverPort = 12000
clientSocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
message = raw_input("Input a sentence:")
clientSocket.sendto(message, (serverName, serverPort))
modifiedMessage, serverAddress = clientSocket.recvfrom(2048)
print modifiedMessage
clientSocket.close()

服务端：

import socket
serverPort = 12000
serverSocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
serverSocket.bind(("", serverPort))
print "Ready to receive"
while True:
message, clientAddress = serverSocket.recvfrom(2048)
modifiedMessage = message.upper()
serverSocket.sendto(modifiedMessage, clientAddress)

TCP：

客户端：

import socket
serverName = "127.0.0.1"
serverPort = 12000
clientSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
clientSocket.connect((serverName, serverPort))
message = raw_input("Input a sentence:")
clientSocket.send(message)
modifiedMessage = clientSocket.recv(2048)
print modifiedMessage
clientSocket.close()

服务端：

import socket
serverPort = 12000
serverSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serverSocket.bind(("", serverPort))
serverSocket.listen(5)
print "Ready to receive"
while True:
connectionSocket, addr = serverSocket.accept()
message = connectionSocket.recv(2048)
modifiedMessage = message.upper()
connectionSocket.send(modifiedMessage)
connectionSocket.close()

两种连接实现了相同功能，即客户端输入一句话，通过udp传出到服务器，服务器将小写字母转换为大写再传回客户端，由客户端打印出来。

对比代码就可以窥见TCP与UDP的一些区别：

1、TCP面向连接，需要额外的三次握手，而UDP不需要；

2、TCP连接建立后，发送数据不再需要地址，直接将数据丢给Socket即可，而UDP每次发送都需要地址；

3、TCP连接的断开需要两边都调用close函数。