Python服务器开发三：Socket

socket是操作系统中I/O的延续，它可以使进程和机器之间的通信成为可能。socket可以看成一个标准的文件描述符。不同的是文件需要用open()函数打开，而socket用socket()

函数建立.recv()、send()函数和read()、write()函数极为相似。

TCP一般通过accept()来为每个连接的客户端建立一个新的scoket。UDP一般只是使用一个单一的socket，完全依靠recvfrom()返回的值来判断该往哪里发送响应。

客户端：

1、建立一个socket：

//SOCK_STREAM表示TCP，SOCK_DGRAM表示UDP，AF_INET表示IPv4

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

2、连接socket

连接socket需要一个tuple参数，来提供IP和端口号：

s.connect((“www.example.com”, 80))

3、

#!/usr/bin/env python

import socket

print "Creating socket...",
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print "done."

print "Looking up port number...",
port = socket.getservbyname('http', 'tcp')
print "done."

print "Connecting to remote host on port %d..." % port,
s.connect(("www.google.com", port))
print "done."

#获取本身的IP和端口号
print "Connected from", s.getsockname()
#获取远程的IP和端口号
print "Connected to", s.getpeername()

文件类对象：

import socket, sys

port = 70
host = sys.argv[1]
filename = sys.argv[2]

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
fd = s.makefile('rw', 0)

fd.write(filename + "\r\n")

for line in fd.readlines():
    sys.stdout.write(line)
    

高级接口：

import urllib, sys

f = urllib.urlopen(sys.argv[1])
while 1:
    buf = f.read(2048)
    if not len(buf):
        break
    sys.stdout.write(buf)

服务器端：

1、建立一个连接：

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

2、设置socket选项：

//socket 端口可立即复用
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

3、绑定socket：

s.bind((host, port))

4、监听：

s.listen(1)

5、接受连接：

while 1:
    clientsock, clientaddr = s.accept()
    print "Got connection from", clientsock.getpeername()
    clientsock.close()

6、

#!/usr/bin/env python

import socket, traceback

host = ''                               # Bind to all interfaces
port = 51423

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))
#这里设定每次最多只有一个等候处理的请求，真正的服务器会设置一个很高的数字。
s.listen(1)

while 1:
    try:
        clientsock, clientaddr = s.accept()
    except KeyboardInterrupt:
        raise
    except:
        traceback.print_exc()
        continue

    # Process the connection

    try:
        print "Got connection from", clientsock.getpeername()
        # Process the request here
    except (KeyboardInterrupt, SystemExit):
        raise
    except:
        traceback.print_exc()

    # Close the connection

    try:
        clientsock.close()
    except KeyboardInterrupt:
        raise
    except:
        traceback.print_exc()

使用UDP：

#!/usr/bin/env python

import socket, traceback

host = ''                               # Bind to all interfaces
port = 51423

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))

while 1:
    try:
        message, address = s.recvfrom(8192)
        print "Got data from", address
        # Echo it back
        s.sendto(message, address)
    except (KeyboardInterrupt, SystemExit):
        raise
    except:
        traceback.print_exc()