基于Python的TCP服务端/客户端简单应用示例

服务端代码：server.py

# -*- coding:utf-8 -*-

import sys
import socket
import argparse

def test_server(host, port):

# 创建TCP套接字
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 启用地址重用
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

# 绑定地址和端口号
srv_addr = (host, port)
sock.bind(srv_addr)

# 侦听客户端
sock.listen(5)

while True:
# 接受客户端连接
client, addr = sock.accept()

# 接受客户端消息
data = client.recv(1024)
if data:
print "Message from client: %s" % data

# 向客户端发送消息
client.send(data)

# 关闭连接
client.close()

if __name__ == "__main__":
'''
parser = argparse.ArgumentParser(description="Socket Server Example")
parser.add_argument("--port", action="store", dest="port", type=int, required=True)
parser.add_argument("--ip", action="store", dest="host", type=str, required=True)
given_args = parser.parse_args()
port = given_args.port
host = given_args.host
test_server(host, port)
'''
if len(sys.argv) == 2:
host = "127.0.0.1"
port = sys.argv[1]
test_server(host, int(port))
elif len(sys.argv) == 3:
host = sys.argv[1]
port = sys.argv[2]
test_server(host, int(port))
else:
print "Input error."

客户端代码：client.py

# -*- coding:utf-8 -*-

import sys
import socket
import argparse

def test_client(host, port):

# 创建TCP套接字
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# 连接服务器
srv_addr = (host, port)
sock.connect(srv_addr)

# 发送并接收数据
try:
# 发送消息
msg = "Test message. This will be echoed."
sock.sendall(msg)

# 接收消息
data = sock.recv(1024)
print "Message from server: %s" % data
except socket.errno, e:
print "Socket error: %s" % str(e)
except Exception as e:
print "Other exception: %s" % str(e)
finally:
sock.close()

if __name__ == "__main__":
parser = argparse.ArgumentParser(description="Socket Server Example")
parser.add_argument("--ip", action="store", dest="host", type=str, required=True)
parser.add_argument("--port", action="store", dest="port", type=int, required=True)
given_args = parser.parse_args()
host = given_args.host
port = given_args.port
test_client(host, port)

几点说明：

1.创建套接字

创建Socket时，AF_INET指定使用IPv4协议，如果要用更先进的IPv6，就指定为AF_INET6。SOCK_DGRAM指定使用面向流的TCP协议，SOCK_STREAM指定使用面向流的UDP协议。

2.套接字地址重用

# 启用地址重用
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

服务端加上上面一句代码就能设定启用重用地址，这样想运行多少次服务器就能运行多少次。如果不加这一句，断开连接之后再马上运行服务器会出现以下错误：

Traceback (most recent call last):
File "server.py", line 54, in <module>
test_server(host, int(port))
File "server.py", line 17, in test_server
sock.bind(srv_addr)
File "/usr/lib/python2.7/socket.py", line 228, in meth
return getattr(self._sock,name)(*args)
socket.error: [Errno 98] Address already in use

3.accept()返回值

accept()函数接受TCP连接并返回（conn,address）,其中conn是新的套接字对象，可以用来接收和发送数据。address是连接客户端的地址。

4.argparse模块

argparse是python用于解析命令行参数和选项的标准模块。
argparse模块的作用是用于解析命令行参数.例如：
python client.py --ip=192.168.31.139 --port=9908
从此命令中解析出参数ip地址192.168.31.139，和端口号9908