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 sysimport socketimport argparsedef 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 sysimport socketimport argparsedef 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