服务器端：
 1 #!/usr/bin/env python
 2 #coding:utf-8
 3 
 4 
 5 import select
 6 import socket
 7 import sys
 8 import Queue
 9 
10 
11 # Create a TCP/IP socket
12 server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
13 server.setblocking(0)#设置0就是非阻塞模式，1就是阻塞模式
14 
15 # Bind the socket to the port
16 server_address = (‘localhost‘, 10000)
17 print >> sys.stderr, ‘starting up on %s port %s‘ % server_address
18 server.bind(server_address)
19 
20 # Listen for incoming connections
21 server.listen(5)#最大允许的连接数是5
22 
23 
24 # Sockets from which we expect to read
25 inputs = [server]
26 
27 # Sockets to which we expect to write
28 outputs = []
29 
30 
31 # Outgoing message queues (socket:Queue)
32 message_queues = {}
33 
34 while inputs:#死循环
35 
36     # Wait for at least one of the sockets to be ready for processing
37     print >>sys.stderr, ‘\nwaiting for the next event‘
38     readable, writable, exceptional = select.select(inputs, outputs, inputs)#第三个是错误信息，这个select就是要检测是否有就绪的文件描述符
39 
40 
41     # Handle inputs
42     for s in readable:#找出已经就绪的连接
43 
44         if s is server:#如果此时是一个新链接
45             # A "readable" server socket is ready to accept a connection
46             connection, client_address = s.accept()
47             print >> sys.stderr, ‘new connection from‘, client_address
48             connection.setblocking(0)
49             inputs.append(connection)
50 
51             # Give the connection a queue for data we want to send
52             message_queues[connection] = Queue.Queue()#每个连接一个q,保证独立不乱
53 
54         else:#此时是老连接，开始接收数据
55             data = http://www.mamicode.com/s.recv(1024)
56             if data:
57                 # A readable client socket has data
58                 print >> sys.stderr, ‘received "%s" from %s‘ % (data, s.getpeername())
59                 message_queues[s].put(data)
60                 # Add output channel for response
61                 if s not in outputs:
62                     outputs.append(s)
63                 else:
64                     # Interpret empty result as closed connection
65                     print >> sys.stderr, ‘closing‘, client_address, ‘after reading no data‘
66                     # Stop listening for input on the connection
67                     if s in outputs:
68                         outputs.remove(s)  # 既然客户端都断开了，我就不用再给它返回数据了，所以这时候如果这个客户端的连接对象还在outputs列表中，就把它删掉
69                     inputs.remove(s)  # inputs中也删除掉
70                     s.close()  # 把这个连接关闭掉
71 
72                     # Remove message queue
73                     del message_queues[s]
74 
75     # Handle outputs
76     for s in writable:
77         try:
78             next_msg = message_queues[s].get_nowait()
79         except Queue.Empty:
80             # No messages waiting so stop checking for writability.
81             print >>sys.stderr, ‘output queue for‘, s.getpeername(), ‘is empty‘
82             outputs.remove(s)
83         else:
84             print >>sys.stderr, ‘sending "%s" to %s‘ % (next_msg, s.getpeername())
85             s.send(next_msg)
86 
87     # Handle "exceptional conditions"
88     for s in exceptional:
89         print >> sys.stderr, ‘handling exceptional condition for‘, s.getpeername()
90         # Stop listening for input on the connection
91         inputs.remove(s)
92         if s in outputs:
93             outputs.remove(s)
94         s.close()
95 
96         # Remove message queue
97         del message_queues[s]