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
filename = sys.argv
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)
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()
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