【Socket編程】篇七之Python實現Socket

一年前使用過C來實現Socket，如今見識了腳本的便利之後，我來嘗試用Python再次實現一遍。

UDP：

客戶端：

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()

服務端：

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：

客戶端：

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()

服務端：

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()

兩種連接實現了相同功能，即客戶端輸入一句話，通過udp傳出到服務器，服務器將小寫字母轉換爲大寫再傳回客戶端，由客戶端打印出來。

對比代碼就可以窺見TCP與UDP的一些區別：

1、TCP面向連接，需要額外的三次握手，而UDP不需要；

2、TCP連接建立後，發送數據不再需要地址，直接將數據丟給Socket即可，而UDP每次發送都需要地址；

3、TCP連接的斷開需要兩邊都調用close函數。