Python网络Socket编程

jieforest · 发表于 2012-11-4 14:12

一直在运行的服务器

对上述代码稍作改动：

import socket
import sys
HOST = '' # Symbolic name meaning all available interfaces
PORT = 8888 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
try:
s.bind((HOST, PORT))
except socket.error , msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
print 'Socket bind complete'
s.listen(10)
print 'Socket now listening'
#now keep talking with the client
while 1:
#wait to accept a connection - blocking call
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
data = conn.recv(1024)
reply = 'OK...' + data
if not data:
break
conn.sendall(reply)
conn.close()
s.close()

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jieforest · 发表于 2012-11-4 14:13

很简单只是加多一个 while 1 语句而已。

继续运行服务器，然后打开另外三个命令行窗口。每个窗口都使用 telnet 命令连接到服务器：

$ telnet localhost 5000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
happy
OK .. happy
Connection closed by foreign host.

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jieforest · 发表于 2012-11-4 14:13

服务器所在的终端窗口显示的是：

$ python server.py
Socket created
Socket bind complete
Socket now listening
Connected with 127.0.0.1:60225
Connected with 127.0.0.1:60237
Connected with 127.0.0.1:60239

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你看服务器再也不退出了，好吧，用 Ctrl+C 关闭服务器，所有的 telnet 终端将会显示 "Connection closed by foreign host."

已经很不错了，但是这样的通讯效率太低了，服务器程序使用循环来接受连接并发送回应，这相当于是一次最多处理一个客户端的请求，而我们要求服务器可同时处理多个请求。

jieforest · 发表于 2012-11-5 14:15

处理多个连接

为了处理多个连接，我们需要一个独立的处理代码在主服务器接收到连接时运行。一种方法是使用线程，服务器接收到连接然后创建一个线程来处理连接收发数据，然后主服务器程序返回去接收新的连接。

下面是我们使用线程来处理连接请求：

import socket
import sys
from thread import *
HOST = '' # Symbolic name meaning all available interfaces
PORT = 8888 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
#Bind socket to local host and port
try:
s.bind((HOST, PORT))
except socket.error , msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
print 'Socket bind complete'
#Start listening on socket
s.listen(10)
print 'Socket now listening'
#Function for handling connections. This will be used to create threads
def clientthread(conn):
#Sending message to connected client
conn.send('Welcome to the server. Type something and hit enter\n') #send only takes string
#infinite loop so that function do not terminate and thread do not end.
while True:
#Receiving from client
data = conn.recv(1024)
reply = 'OK...' + data
if not data:
break
conn.sendall(reply)
#came out of loop
conn.close()
#now keep talking with the client
while 1:
#wait to accept a connection - blocking call
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
#start new thread takes 1st argument as a function name to be run, second is the tuple of arguments to the function.
start_new_thread(clientthread ,(conn,))
s.close()

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jieforest · 发表于 2012-11-5 14:15

运行上述服务端程序，然后像之前一样打开三个终端窗口并执行 telent 命令：

$ telnet localhost 8888
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Welcome to the server. Type something and hit enter
hi
OK...hi
asd
OK...asd
cv
OK...cv

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jieforest · 发表于 2012-11-5 14:16

服务器端所在终端窗口输出信息如下：

$ python server.py
Socket created
Socket bind complete
Socket now listening
Connected with 127.0.0.1:60730
Connected with 127.0.0.1:60731

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线程接管了连接并返回相应数据给客户端。

这便是我们所要介绍的服务器端编程。

jieforest · 发表于 2012-11-5 14:16

结论

到这里为止，你已经学习了 Python 的 Socket 基本编程，你可自己动手编写一些例子来强化这些知识。

你可能会遇见一些问题：Bind failed. Error Code : 98 Message Address already in use，碰见这种问题只需要简单更改服务器端口即可。

jieforest · 发表于 2012-11-5 14:16

over.

ts12345 · 发表于 2012-11-21 22:28

up,where is the function which called start_new_thread?

Python网络Socket编程

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