python 通过UDP传输文件

使用一个简单的python脚本将一个本地文件以码流的形式，通过UDP协议发送到对端：

import socket
import os
import stat
import struct

MAX_PACK_SIZE = 100
DEST_IP = 'localhost'
DEST_PORT = 17800

filename = raw_input("input filename")

filesize = os.stat(filename)[stat.ST_SIZE]

f = open(filename, "rb")

chList = []
for i in range(0, filesize):
(ch,) = struct.unpack("B", f.read(1))
chList.append(ch)

client = socket.socket( socket.AF_INET, socket.SOCK_DGRAM )

packSize = 0
string = ""
args = []
for i in range(0, filesize):
packSize = packSize + 1
string = string + struct.pack("B", chList[i])
if (MAX_PACK_SIZE == packSize or i == filesize - 1):
client.sendto(string, (DEST_IP, DEST_PORT))
packSize = 0
string = ""
client.close()

使用到的知识点：
1、UDP客户端最简单的实现:
client = socket.socket( socket.AF_INET, socket.SOCK_DGRAM )
client.sendto(string, (DEST_IP, DEST_PORT))
client.close()

2、python中对码流的操作：struct.pack 和 struct.unpack的使用
(ch,) = struct.unpack("B", f.read(1))
string = string + struct.pack("B", chList[i])

3、二进制文件的读取：
f = open(filename, "rb")

4、获得系统中某个文件的字节数
filesize = os.stat(filename)[stat.ST_SIZE]