python之优雅处理套接字错误

#!/usr/local/bin/python3.5
#coding:utf-8

import sys
import socket
import argparse

def main():
#setup argument Parsing
parser = argparse.ArgumentParser(description='socket error examples')
parser.add_argument('--host', action='store', dest='host', required=False)
parser.add_argument('--port',action='store', dest='port', type=int, required=False)
parser.add_argument('--file', action='store', dest='file', required=False)
given_args=parser.parse_args()
host = given_args.host
port = given_args.port
filename = given_args.file

#first try-except block --create socket
try:
s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error as e:
print("error creating socket:" % e)
sys.exit(1)

#Second try-except block -- connect to given host/PORT
try:
s.connect((host, port))
except socket.gaierror as e:
print("address-related error connectiong to server : %s" % e )
sys.exit(1)
except socket.error as e:
print("connection error: %s" % e)
sys.exit(1)

#third try-except block -- sending data
try:
s.sendall(("GET %s HTTP/1.0\r\n\r\n" % filename).encode(encoding='utf-8'))
except socket.error as e:
print("Error sending data: %s" % e)
sys.exit(1)

while 1:
#Fourth tr-except block --waiting to receive data from remote host
try:
buf = str(s.recv(2048), 'utf-8')
except socket.error as e:
print("error receiving data: %s" % e)
sys.exit(1)
if not len(buf):
break
# write the received data
sys.stdout.write(buf)

if __name__ == '__main__':
main()