Python的网络编程主要支持两种网络协议:TCP和UDP。这两种协议都通过叫Socket的编程抽象进行处理。Socket起源于Unix,是类似于文件的存在,可以像文件一样进行I/O、打开、关闭等操作,最主要的是它可以实现网络上不同主机的进程间通信,所以基本上Socket是任何一种网络通讯中最基础的内容。
Python中建立一个套接字很简单:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- import socket
- s = socket.socket(family, type)
</pre>
地址族
family为地址族,该族指定要使用的网络协议,主要使用的有:
- AF_INET:IPv4协议(TCP,UDP)
- AF_INET6:IPv6协议(TCP,UDP)
- AF_UNIX:UNIX域协议,用于同一台机器的进程间通讯
套接字类型
type为套接字类型,指定给定的协议组中使用的通信类型:
- SOCK_STREAM:用于TCP
- SOCK_DGRAM:用于UDP
TCP和UDP都是基于Client/Server的编程模型,所以Socket编程也分为客户端和服务器端,以TCP为例:
TCP客户端编程
要获取远程主机的ip地址,可以使用socket标准库提供的gethostbyname方法:
socket套接字实例s可用于客户端的方法有以下几个:
- s.connect(addr):连接服务器端套接字。addr格式取决于地址族,对于IPv4来说,是一个包含ip地址与端口的元组,(host, port)。连接失败会报socket.error错误。
- s.sendall(string):尝试发送所有数据,成功则返回None,失败则报异常。
- s.recv(bufsize):接收数据,bufsize指定接收的最大数据量。
- s.close:关闭套接字
OK,现在可以用socket向远程主机发送一个HTTP GET请求了:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- # -*- coding: utf-8 -*-
- import socket
- s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #建立套接字
- host = 'www.baidu.com'
- port = 80
- ip = socket.gethostbyname(host) #获取ip
- s.connect((ip, port)) #建立连接
- message = 'GET / HTTP/1.1rnrn'
- s.sendall(message) #发送GET请求
- r = s.recv(4096) #接收数据
- print r
- s.close #关闭套接字
</pre>
返回:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- HTTP/1.1 302 Moved Temporarily
- Date: Wed, 10 Jan 2018 18:56:45 GMT
- Content-Type: text/html
- Content-Length: 225
- Connection: Keep-Alive
- Location: http://www.baidu.com/search/error.html
- Server: BWS/1.1
- X-UA-Compatible: IE=Edge,chrome=1
- BDPAGETYPE: 3
- Set-Cookie: BDSVRTM=0; path=/
</pre>
下面我们可以实现自己的服务器。
TCP服务器端编程
Socket实例与服务器端编程有关的方法有以下几个:
- s.bind(addr):addr也是(host, port)形式的元组,将套接字绑定到特定的地址和端口上。空字符串表示任意地址,'broadcast'可以用做发送广播信息。
- s.listen(backlog):开始监听连接,backlog为最大挂起连接次数。
- s.accept:返回元组(conn,addr),conn为新的套接字,可以用来发送和接收数据。addr是客户端的套接字地址。
- s.recv、s.sendall和s.close与客户端同。
现在写一个将客户端发送来的信息发送回去的服务器:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- # -*- coding: utf-8 -*-
- import socket
- import sys
- HOST = ''
- PORT = 8088
- s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
- s.bind((HOST, PORT))
- s.listen(5)
- print '开始监听'
- conn, addr = s.accept
- print 'Connected with ' + addr[0] + ':' + str(addr[1])
- data = conn.recv(1024)
- conn.sendall(data)
- conn.close
- s.close
</pre>
运行:
服务器开始监听连接了。修改一下刚才写的客户端程序:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- # -*- coding: utf-8 -*-
- import socket
- s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
- host = 'localhost'
- port = 8088
- s.connect((host, port)) #建立连接
- message = 'GET / HTTP/1.1rnrn'
- s.sendall(message) #发送GET请求
- r = s.recv(4096) #接收数据
- print r
- s.close #关闭套接字
</pre>
运行,连接本地的服务器,服务器端输出:
连接成功。客户端输出:
发送的消息被返回了。
这就是一个最简单的服务器了。上述服务器只能处理一次连接,这显然不是我们想看到的,保持一直运行:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- # -*- coding: utf-8 -*-
- import socket
- import sys
- HOST = ''
- PORT = 8088
- s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
- s.bind((HOST, PORT))
- s.listen(5)
- print '开始监听'
- while True:
- conn, addr = s.accept
- print 'Connected with ' + addr[0] + ':' + str(addr[1])
- data = conn.recv(1024)
- conn.sendall(data)
- conn.close
- s.close
</pre>
现在就可以使用客户端无限连接了:
服务器端多线程处理连接
现在服务器端虽然可以处理无限多个连接,但只能一个一个的处理,后面的客户端连接只能等待前面的连接完成才能发送数据。要同时处理多个连接,可以使用多线程。服务器端接收到新的连接后,开启一个线程处理新连接,主线程去建立下一个连接。
服务器端:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- # -*- coding: utf-8 -*-
- import socket
- import threading
- HOST = ''
- PORT = 8088
- s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
- s.bind((HOST, PORT))
- s.listen(5)
- print '开始监听'
- def runThread(conn):
- data = conn.recv(1024)
- print data
- conn.sendall(data)
- conn.close
- while True:
- conn, addr = s.accept
- print 'Connected with ' + addr[0] + ':' + str(addr[1])
- t = threading.Thread(target=runThread, args=(conn,))
- t.daemon = True
- t.start
</pre>
客户端启动多个连接:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- # -*- coding: utf-8 -*-
- import socket
- import time
- import threading
- def run:
- s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
- host = 'localhost'
- port = 8088
- s.connect((host, port))
- message = 'GET / HTTP/1.1rnrn'
- s.sendall(message)
- print s.recv(4096)
- s.close
- if __name__ == '__main__':
- for i in xrange(4):
- t = threading.Thread(target=run)
- t.start
</pre>
运行:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- 开始监听
- Connected with 127.0.0.1:61772
- GET / HTTP/1.1
- Connected with 127.0.0.1:61773
- GET / HTTP/1.1
- Connected with 127.0.0.1:61774
- GET / HTTP/1.1
- Connected with 127.0.0.1:61775
- GET / HTTP/1.1
</pre>
UDP编程
UDP与TCP的不同之处在于UDP是不用建立连接的。
在此需要使用s.recvfrom与s.sendto方法,前者与s.recv相同,但返回(data, addr)的元组,addr为数据发送端的套接字地址,后者发送数据时需要加入要发送的远程地址。
服务器:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- # -*- coding: utf-8 -*-
- import socket
- s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
- s.bind(('', 10000))
- while True:
- data, addr = s.recvfrom(1024)
- print '接收到%s的连接'%str(addr)
- s.sendto(data, addr)
</pre>
客户端:
<pre style="-webkit-tap-highlight-color: transparent; box-sizing: border-box; font-family: Consolas, Menlo, Courier, monospace; font-size: 16px; white-space: pre-wrap; position: relative; line-height: 1.5; color: rgb(153, 153, 153); margin: 1em 0px; padding: 12px 10px; background: rgb(244, 245, 246); border: 1px solid rgb(232, 232, 232); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
- # -*- coding: utf-8 -*-
- import socket
- s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
- s.sendto('Hello World', ('localhost', 10000))
- r, addr = s.recvfrom(1024)
- print r
- s.close
</pre>
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