python之socket编程

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python之socket编程

shadowcat 2017-03-15 11:23:00 浏览1136
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From : http://www.cnblogs.com/aylin/p/5572104.html


1、socket

        socket起源于Unix,而Unix/Linux基本哲学之一就是“一切皆文件”,对于文件用【打开】【读写】【关闭】模式来操作。socket就是该模式的一个实现,socket即是一种特殊的文件,一些socket函数就是对其进行的操作(读/写IO、打开、关闭)
        基本上,Socket 是任何一种计算机网络通讯中最基础的内容。例如当你在浏览器地址栏中输入 http://www.cnblogs.com/ 时,你会打开一个套接字,然后连接到 http://www.cnblogs.com/ 并读取响应的页面然后然后显示出来。而其他一些聊天客户端如 gtalk 和 skype 也是类似。任何网络通讯都是通过 Socket 来完成的。

Python 官方关于 Socket 的函数请看 http://docs.python.org/library/socket.html

socket和file的区别:

  1、file模块是针对某个指定文件进行【打开】【读写】【关闭】

  2、socket模块是针对 服务器端 和 客户端Socket 进行【打开】【读写】【关闭】


python 编写server的步骤:

1. 第一步是创建socket对象。
    调用socket构造函数。如:
    socket = socket.socket( family, type )
    family参数代表地址家族,可为AF_INET或AF_UNIX。AF_INET家族包括Internet地址,AF_UNIX家族用于同一台机器上的进程间通信。
    type参数代表套接字类型,可为SOCK_STREAM(流套接字)和SOCK_DGRAM(数据报套接字)。
2. 第二步是将socket绑定到指定地址。
    这是通过socket对象的bind方法来实现的:
    socket.bind( address )
    由AF_INET所创建的套接字,address地址必须是一个双元素元组,格式是(host,port)。host代表主机,port代表端口号。
    如果端口号正在使用、主机名不正确或端口已被保留,bind方法将引发socket.error异常。
3. 第三步是使用socket套接字的listen方法接收连接请求。
    socket.listen( backlog )
    backlog指定最多允许多少个客户连接到服务器。它的值至少为1。收到连接请求后,这些请求需要排队,如果队列满,就拒绝请求。
4. 第四步是服务器套接字通过socket的accept方法等待客户请求一个连接。
    connection, address = socket.accept()
    调用accept方法时,socket会时入“waiting”状态。客户请求连接时,方法建立连接并返回服务器。
	accept方法返回一个含有两个元素的元组(connection,address)。
	第一个元素connection是新的socket对象,服务器必须通过它与客户通信;
	第二个元素 address是客户的Internet地址。
5. 第五步是处理阶段。
    服务器和客户端通过send和recv方法通信(传输 数据)。
	服务器调用send,并采用字符串形式向客户发送信息。send方法返回已发送的字符个数。
	服务器使用recv方法从客户接收信息。调用recv 时,服务器必须指定一个整数,它对应于可通过本次方法调用来接收的最大数据量。
	recv方法在接收数据时会进入“blocked”状态,最后返回一个字符串,用它表示收到的数据。
	如果发送的数据量超过了recv所允许的,数据会被截短。多余的数据将缓冲于接收端。以后调用recv时,
	多余的数据会从缓冲区 删除(以及自上次调用recv以来,客户可能发送的其它任何数据)。
6. 传输结束,服务器调用socket的close方法关闭连接。

python编写client的步骤:

1. 创建一个socket以连接服务器:socket = socket.socket( family, type )
2. 使用socket的connect方法连接服务器。对于AF_INET家族,连接格式如下:
    socket.connect( (host,port) )
    host代表服务器主机名或IP,port代表服务器进程所绑定的端口号。
	如连接成功,客户就可通过套接字与服务器通信,如果连接失败,会引发socket.error异常。
3. 处理阶段,客户和服务器将通过send方法和recv方法通信。
4. 传输结束,客户通过调用socket的close方法关闭连接。

# server.py
if __name__ == '__main__':
    import socket
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.bind(('localhost', 8001))
    sock.listen(5)
    while True:
        connection,address = sock.accept()
        try:
            connection.settimeout(5)
            buf = connection.recv(1024)
            if buf == '1':
                connection.send('welcome to server!')
            else:
                connection.send('please go out!')
        except socket.timeout:
            print 'time out'
        connection.close()

		
# client.py		
if __name__ == '__main__':
    import socket
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.connect(('localhost', 8001))
    import time
    time.sleep(2)
    sock.send('1')
    print sock.recv(1024)
    sock.close()

Python 提供了两个基本的 socket 模块。

   第一个是 Socket,它提供了标准的 BSD Sockets API。

   第二个是 SocketServer, 它提供了服务器中心类,可以简化网络服务器的开发。

下面讲的是Socket模块功能

1、Socket 类型

套接字格式:

socket(family,type[,protocal]) 使用给定的地址族、套接字类型、协议编号(默认为0)来创建套接字。

socket类型

描述

socket.AF_UNIX

只能够用于单一的Unix系统进程间通信

socket.AF_INET

服务器之间网络通信

socket.AF_INET6

IPv6

socket.SOCK_STREAM

流式socket , for TCP

socket.SOCK_DGRAM

数据报式socket , for UDP

socket.SOCK_RAW

原始套接字,普通的套接字无法处理ICMPIGMP等网络报文,而SOCK_RAW可以;其次,SOCK_RAW也可以处理特殊的IPv4报文;此外,利用原始套接字,可以通过IP_HDRINCL套接字选项由用户构造IP头。

socket.SOCK_SEQPACKET

可靠的连续数据包服务

创建TCP Socket

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

创建UDP Socket

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


2、Socket 函数

注意点:

1TCP发送数据时,已建立好TCP连接,所以不需要指定地址。UDP是面向无连接的,每次发送要指定是发给谁。

2)服务端与客户端不能直接发送列表,元组,字典。需要字符串化repr(data)

socket函数

描述

服务端socket函数

s.bind(address)

将套接字绑定到地址AF_INET,以元组(host,port)的形式表示地址.

s.listen(backlog)

开始监听TCP传入连接。backlog指定在拒绝连接之前,操作系统可以挂起的最大连接数量。该值至少为1,大部分应用程序设为5就可以了。

s.accept()

接受TCP连接并返回(conn,address,其中conn是新的套接字对象,可以用来接收和发送数据。address是连接客户端的地址。

客户端socket函数

s.connect(address)

连接到address处的套接字。一般address的格式为元组(hostname,port),如果连接出错,返回socket.error错误。

s.connect_ex(adddress)

功能与connect(address)相同,但是成功返回0,失败返回errno的值。

公共socket函数

s.recv(bufsize[,flag])

接受TCP套接字的数据。数据以字符串形式返回,bufsize指定要接收的最大数据量。flag提供有关消息的其他信息,通常可以忽略。

s.send(string[,flag])

发送TCP数据。将string中的数据发送到连接的套接字。返回值是要发送的字节数量,该数量可能小于string的字节大小。

s.sendall(string[,flag])

完整发送TCP数据。将string中的数据发送到连接的套接字,但在返回之前会尝试发送所有数据。成功返回None,失败则抛出异常。

s.recvfrom(bufsize[.flag])

接受UDP套接字的数据。与recv()类似,但返回值是(data,address)。其中data是包含接收数据的字符串,address是发送数据的套接字地址。

s.sendto(string[,flag],address)

发送UDP数据。将数据发送到套接字,address是形式为(ipaddrport)的元组,指定远程地址。返回值是发送的字节数。

s.close()

关闭套接字。

s.getpeername()

返回连接套接字的远程地址。返回值通常是元组(ipaddr,port)。

s.getsockname()

返回套接字自己的地址。通常是一个元组(ipaddr,port)

s.setsockopt(level,optname,value)

设置给定套接字选项的值。

s.getsockopt(level,optname[.buflen])

返回套接字选项的值。

s.settimeout(timeout)

设置套接字操作的超时期,timeout是一个浮点数,单位是秒。值为None表示没有超时期。一般,超时期应该在刚创建套接字时设置,因为它们可能用于连接的操作(如connect()

s.gettimeout()

返回当前超时期的值,单位是秒,如果没有设置超时期,则返回None

s.fileno()

返回套接字的文件描述符。

s.setblocking(flag)

如果flag0,则将套接字设为非阻塞模式,否则将套接字设为阻塞模式(默认值)。非阻塞模式下,如果调用recv()没有发现任何数据,或send()调用无法立即发送数据,那么将引起socket.error异常。

s.makefile()

创建一个与该套接字相关连的文件

3、socket编程思路

TCP服务端:

创建套接字,绑定套接字到本地IP与端口

   # socket.socket(socket.AF_INET,socket.SOCK_STREAM) , s.bind()

开始监听连接                   #s.listen()

进入循环,不断接受客户端的连接请求              #s.accept()

然后接收传来的数据,并发送给对方数据         #s.recv() , s.sendall()

传输完毕后,关闭套接字                     #s.close()


TCP客户端:

创建套接字,连接远端地址

       # socket.socket(socket.AF_INET,socket.SOCK_STREAM) , s.connect()

连接后发送数据和接收数据          # s.sendall(), s.recv()

传输完毕后,关闭套接字          #s.close()

4、Socket编程之服务端代码:

# Server.py
#!/usr/bin/python
import socket   #socket模块
import commands   #执行系统命令模块
HOST='10.0.0.245'
PORT=50007
s= socket.socket(socket.AF_INET,socket.SOCK_STREAM)   #定义socket类型,网络通信,TCP
s.bind((HOST,PORT))   #套接字绑定的IP与端口
s.listen(1)         #开始TCP监听
while 1:
       conn,addr=s.accept()   #接受TCP连接,并返回新的套接字与IP地址
       print'Connected by',addr    #输出客户端的IP地址
       while 1:
                data=conn.recv(1024)    #把接收的数据实例化
               cmd_status,cmd_result=commands.getstatusoutput(data)   #commands.getstatusoutput执行系统命令(即shell命令),返回两个结果,第一个是状态,成功则为0,第二个是执行成功或失败的输出信息
                if len(cmd_result.strip()) ==0:   #如果输出结果长度为0,则告诉客户端完成。此用法针对于创建文件或目录,创建成功不会有输出信息
                        conn.sendall('Done.')
                else:
                       conn.sendall(cmd_result)   #否则就把结果发给对端(即客户端)
conn.close()     #关闭连接


# Client.py
#!/usr/bin/python
import socket
HOST='10.0.0.245'
PORT=50007
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)      #定义socket类型,网络通信,TCP
s.connect((HOST,PORT))       #要连接的IP与端口
while 1:
       cmd=raw_input("Please input cmd:")       #与人交互,输入命令
       s.sendall(cmd)      #把命令发送给对端
       data=s.recv(1024)     #把接收的数据定义为变量
        print data         #输出变量
s.close()   #关闭连接

socket更多功能

def bind(self, address): # real signature unknown; restored from __doc__
        """
        bind(address)
        
        Bind the socket to a local address.  For IP sockets, the address is a
        pair (host, port); the host must refer to the local host. For raw packet
        sockets the address is a tuple (ifname, proto [,pkttype [,hatype]])
        """
'''将套接字绑定到本地地址。是一个IP套接字的地址对(主机、端口),主机必须参考本地主机。'''
        pass

    def close(self): # real signature unknown; restored from __doc__
        """
        close()
        
        Close the socket.  It cannot be used after this call.
        """
        '''关闭socket'''
        pass

    def connect(self, address): # real signature unknown; restored from __doc__
        """
        connect(address)
        
        Connect the socket to a remote address.  For IP sockets, the address
        is a pair (host, port).
        """
        '''将套接字连接到远程地址。IP套接字的地址'''
        pass

    def connect_ex(self, address): # real signature unknown; restored from __doc__
        """
        connect_ex(address) -> errno
        
        This is like connect(address), but returns an error code (the errno value)
        instead of raising an exception when an error occurs.
        """
        pass

    def detach(self): # real signature unknown; restored from __doc__
        """
        detach()
        
        Close the socket object without closing the underlying file descriptor.
        The object cannot be used after this call, but the file descriptor
        can be reused for other purposes.  The file descriptor is returned.
        """
'''关闭套接字对象没有关闭底层的文件描述符。'''
        pass

    def fileno(self): # real signature unknown; restored from __doc__
        """
        fileno() -> integer
        
        Return the integer file descriptor of the socket.
        """
        '''返回整数的套接字的文件描述符。'''
        return 0

    def getpeername(self): # real signature unknown; restored from __doc__
        """
        getpeername() -> address info
        
        Return the address of the remote endpoint.  For IP sockets, the address
        info is a pair (hostaddr, port).
            """
        '''返回远程端点的地址。IP套接字的地址'''
        pass

    def getsockname(self): # real signature unknown; restored from __doc__
        """
        getsockname() -> address info
        
        Return the address of the local endpoint.  For IP sockets, the address
        info is a pair (hostaddr, port).
        """
        '''返回远程端点的地址。IP套接字的地址'''
        pass

    def getsockopt(self, level, option, buffersize=None): # real signature unknown; restored from __doc__
        """
        getsockopt(level, option[, buffersize]) -> value
        
        Get a socket option.  See the Unix manual for level and option.
        If a nonzero buffersize argument is given, the return value is a
        string of that length; otherwise it is an integer.
        """
        '''得到一个套接字选项'''
        pass

    def gettimeout(self): # real signature unknown; restored from __doc__
        """
        gettimeout() -> timeout
        
        Returns the timeout in seconds (float) associated with socket 
        operations. A timeout of None indicates that timeouts on socket 
        operations are disabled.
        """
        '''返回的超时秒数(浮动)与套接字相关联'''
        return timeout

    def ioctl(self, cmd, option): # real signature unknown; restored from __doc__
        """
        ioctl(cmd, option) -> long
        
        Control the socket with WSAIoctl syscall. Currently supported 'cmd' values are
        SIO_RCVALL:  'option' must be one of the socket.RCVALL_* constants.
        SIO_KEEPALIVE_VALS:  'option' is a tuple of (onoff, timeout, interval).
        """
        return 0

    def listen(self, backlog=None): # real signature unknown; restored from __doc__
        """
        listen([backlog])
        
        Enable a server to accept connections.  If backlog is specified, it must be
        at least 0 (if it is lower, it is set to 0); it specifies the number of
        unaccepted connections that the system will allow before refusing new
        connections. If not specified, a default reasonable value is chosen.
        """
        '''使服务器能够接受连接。'''
        pass

    def recv(self, buffersize, flags=None): # real signature unknown; restored from __doc__
        """
        recv(buffersize[, flags]) -> data
        
        Receive up to buffersize bytes from the socket.  For the optional flags
        argument, see the Unix manual.  When no data is available, block until
        at least one byte is available or until the remote end is closed.  When
        the remote end is closed and all data is read, return the empty string.
        """
'''当没有数据可用,阻塞,直到至少一个字节是可用的或远程结束之前关闭。'''
        pass

    def recvfrom(self, buffersize, flags=None): # real signature unknown; restored from __doc__
        """
        recvfrom(buffersize[, flags]) -> (data, address info)
        
        Like recv(buffersize, flags) but also return the sender's address info.
        """
        pass

    def recvfrom_into(self, buffer, nbytes=None, flags=None): # real signature unknown; restored from __doc__
        """
        recvfrom_into(buffer[, nbytes[, flags]]) -> (nbytes, address info)
        
        Like recv_into(buffer[, nbytes[, flags]]) but also return the sender's address info.
        """
        pass

    def recv_into(self, buffer, nbytes=None, flags=None): # real signature unknown; restored from __doc__
        """
        recv_into(buffer, [nbytes[, flags]]) -> nbytes_read
        
        A version of recv() that stores its data into a buffer rather than creating 
        a new string.  Receive up to buffersize bytes from the socket.  If buffersize 
        is not specified (or 0), receive up to the size available in the given buffer.
        
        See recv() for documentation about the flags.
        """
        pass

    def send(self, data, flags=None): # real signature unknown; restored from __doc__
        """
        send(data[, flags]) -> count
        
        Send a data string to the socket.  For the optional flags
        argument, see the Unix manual.  Return the number of bytes
        sent; this may be less than len(data) if the network is busy.
        """
        '''发送一个数据字符串到套接字。'''
        pass

    def sendall(self, data, flags=None): # real signature unknown; restored from __doc__
        """
        sendall(data[, flags])
        
        Send a data string to the socket.  For the optional flags
        argument, see the Unix manual.  This calls send() repeatedly
        until all data is sent.  If an error occurs, it's impossible
        to tell how much data has been sent.
        """
        '''发送一个数据字符串到套接字,直到所有数据发送完成'''
        pass

    def sendto(self, data, flags=None, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 
        """
        sendto(data[, flags], address) -> count
        
        Like send(data, flags) but allows specifying the destination address.
        For IP sockets, the address is a pair (hostaddr, port).
        """
        pass

    def setblocking(self, flag): # real signature unknown; restored from __doc__
        """
        setblocking(flag)
        
        Set the socket to blocking (flag is true) or non-blocking (false).
        setblocking(True) is equivalent to settimeout(None);
        setblocking(False) is equivalent to settimeout(0.0).
        """
'''是否阻塞(默认True),如果设置False,那么accept和recv时一旦无数据,则报错。'''
        pass

    def setsockopt(self, level, option, value): # real signature unknown; restored from __doc__
        """
        setsockopt(level, option, value)
        
        Set a socket option.  See the Unix manual for level and option.
        The value argument can either be an integer or a string.
        """
        pass

    def settimeout(self, timeout): # real signature unknown; restored from __doc__
        """
        settimeout(timeout)
        
        Set a timeout on socket operations.  'timeout' can be a float,
        giving in seconds, or None.  Setting a timeout of None disables
        the timeout feature and is equivalent to setblocking(1).
        Setting a timeout of zero is the same as setblocking(0).
        """
        pass

    def share(self, process_id): # real signature unknown; restored from __doc__
        """
        share(process_id) -> bytes
        
        Share the socket with another process.  The target process id
        must be provided and the resulting bytes object passed to the target
        process.  There the shared socket can be instantiated by calling
        socket.fromshare().
        """
        return b""

    def shutdown(self, flag): # real signature unknown; restored from __doc__
        """
        shutdown(flag)
        
        Shut down the reading side of the socket (flag == SHUT_RD), the writing side
        of the socket (flag == SHUT_WR), or both ends (flag == SHUT_RDWR).
        """
        pass

    def _accept(self): # real signature unknown; restored from __doc__
        """
        _accept() -> (integer, address info)
        
        Wait for an incoming connection.  Return a new socket file descriptor
        representing the connection, and the address of the client.
        For IP sockets, the address info is a pair (hostaddr, port).
        """
        pass
    
注:撸主知道大家懒,所以把全部功能的中文标记在每个功能的下面啦。下面撸主列一些经常用到的吧

sk.bind(address)
  s.bind(address) 将套接字绑定到地址。address地址的格式取决于地址族。在AF_INET下,以元组(host,port)的形式表示地址。
sk.listen(backlog)
  开始监听传入连接。backlog指定在拒绝连接之前,可以挂起的最大连接数量。backlog等于5,表示内核已经接到了连接请求,但服务器还没有调用accept进行处理的连接个数最大为5。这个值不能无限大,因为要在内核中维护连接队列
sk.setblocking(bool)
  是否阻塞(默认True),如果设置False,那么accept和recv时一旦无数据,则报错。
sk.accept()
  接受连接并返回(conn,address),其中conn是新的套接字对象,可以用来接收和发送数据。address是连接客户端的地址。
  接收TCP 客户的连接(阻塞式)等待连接的到来
sk.connect(address)
  连接到address处的套接字。一般,address的格式为元组(hostname,port),如果连接出错,返回socket.error错误。
sk.connect_ex(address)
  同上,只不过会有返回值,连接成功时返回 0 ,连接失败时候返回编码,例如:10061
sk.close()
  关闭套接字
sk.recv(bufsize[,flag])
  接受套接字的数据。数据以字符串形式返回,bufsize指定最多可以接收的数量。flag提供有关消息的其他信息,通常可以忽略。
sk.recvfrom(bufsize[.flag])
  与recv()类似,但返回值是(data,address)。其中data是包含接收数据的字符串,address是发送数据的套接字地址。
sk.send(string[,flag])
  将string中的数据发送到连接的套接字。返回值是要发送的字节数量,该数量可能小于string的字节大小。即:可能未将指定内容全部发送。
sk.sendall(string[,flag])
  将string中的数据发送到连接的套接字,但在返回之前会尝试发送所有数据。成功返回None,失败则抛出异常。内部通过递归调用send,将所有内容发送出去。
sk.sendto(string[,flag],address)
  将数据发送到套接字,address是形式为(ipaddr,port)的元组,指定远程地址。返回值是发送的字节数。该函数主要用于UDP协议。
sk.settimeout(timeout)
  设置套接字操作的超时期,timeout是一个浮点数,单位是秒。值为None表示没有超时期。一般,超时期应该在刚创建套接字时设置,因为它们可能用于连接的操作(如 client 连接最多等待5s )
sk.getpeername()
  返回连接套接字的远程地址。返回值通常是元组(ipaddr,port)。
sk.getsockname()
  返回套接字自己的地址。通常是一个元组(ipaddr,port)
sk.fileno()
  套接字的文件描述符

TCP:

案例一:机器人聊天

import  socketserver
服务端

class Myserver(socketserver.BaseRequestHandler):

    def handle(self):

        conn = self.request
        conn.sendall(bytes("你好,我是机器人",encoding="utf-8"))
        while True:
            ret_bytes = conn.recv(1024)
            ret_str = str(ret_bytes,encoding="utf-8")
            if ret_str == "q":
                break
            conn.sendall(bytes(ret_str+"你好我好大家好",encoding="utf-8"))

if __name__ == "__main__":
    server = socketserver.ThreadingTCPServer(("127.0.0.1",8080),Myserver)
    server.serve_forever()

客户端

import socket

obj = socket.socket()

obj.connect(("127.0.0.1",8080))

ret_bytes = obj.recv(1024)
ret_str = str(ret_bytes,encoding="utf-8")
print(ret_str)

while True:
    inp = input("你好请问您有什么问题? \n >>>")
    if inp == "q":
        obj.sendall(bytes(inp,encoding="utf-8"))
        break
    else:
        obj.sendall(bytes(inp, encoding="utf-8"))
        ret_bytes = obj.recv(1024)
        ret_str = str(ret_bytes,encoding="utf-8")
        print(ret_str)

案例二 上传文件

服务端

import socket

sk = socket.socket()

sk.bind(("127.0.0.1",8080))
sk.listen(5)

while True:
    conn,address = sk.accept()
    conn.sendall(bytes("欢迎光临我爱我家",encoding="utf-8"))

    size = conn.recv(1024)
    size_str = str(size,encoding="utf-8")
    file_size = int(size_str)

    conn.sendall(bytes("开始传送", encoding="utf-8"))

    has_size = 0
    f = open("db_new.jpg","wb")
    while True:
        if file_size == has_size:
            break
        date = conn.recv(1024)
        f.write(date)
        has_size += len(date)

    f.close()

客户端

import socket
import os

obj = socket.socket()

obj.connect(("127.0.0.1",8080))

ret_bytes = obj.recv(1024)
ret_str = str(ret_bytes,encoding="utf-8")
print(ret_str)

size = os.stat("yan.jpg").st_size
obj.sendall(bytes(str(size),encoding="utf-8"))

obj.recv(1024)

with open("yan.jpg","rb") as f:
    for line in f:
        obj.sendall(line)

UDP:

udp传输

import socket
ip_port = ('127.0.0.1',9999)
sk = socket.socket(socket.AF_INET,socket.SOCK_DGRAM,0)
sk.bind(ip_port)

while True:
    data = sk.recv(1024)
    print data




import socket
ip_port = ('127.0.0.1',9999)

sk = socket.socket(socket.AF_INET,socket.SOCK_DGRAM,0)
while True:
    inp = input('数据:').strip()
    if inp == 'exit':
        break
    sk.sendto(bytes(inp,encoding = "utf-8"),ip_port)

sk.close()

WEB服务应用:

#!/usr/bin/env python
#coding:utf-8
import socket
  
def handle_request(client):
    buf = client.recv(1024)
    client.send("HTTP/1.1 200 OK\r\n\r\n")
    client.send("Hello, World")
  
def main():
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.bind(('localhost',8080))
    sock.listen(5)
  
    while True:
        connection, address = sock.accept()
        handle_request(connection)
        connection.close()
  
if __name__ == '__main__':
  main()


2、IO多路复用

I/O(input/output),即输入/输出端口。每个设备都会有一个专用的I/O地址,用来处理自己的输入输出信息。首先什么是I/O:I/O分为磁盘io和网络io,这里说的是网络io
IO多路复用:I/O多路复用指:通过一种机制,可以监视多个描述符(socket),一旦某个描述符就绪(一般是读就绪或者写就绪),能够通知程序进行相应的读写操作。
Linux中的 select,poll,epoll 都是IO多路复用的机制。
Linux下网络I/O使用socket套接字来通信,普通I/O模型只能监听一个socket,而I/O多路复用可同时监听多个socket.
I/O多路复用避免阻塞在io上,原本为多进程或多线程来接收多个连接的消息变为单进程或单线程保存多个socket的状态后轮询处理.

Python中有一个select模块,其中提供了:select、poll、epoll三个方法,分别调用系统的 select,poll,epoll 从而实现IO多

Windows Python: 提供: select
Mac Python:     提供: select
Linux Python:   提供: select、poll、epoll

对于select模块操作的方法:

句柄列表11, 句柄列表22, 句柄列表33 = select.select(句柄序列1, 句柄序列2, 句柄序列3, 超时时间)
  
参数: 可接受四个参数(前三个必须)
返回值:三个列表
  
select方法用来监视文件句柄,如果句柄发生变化,则获取该句柄。
1、当 参数1 序列中的句柄发生可读时(accetp和read),则获取发生变化的句柄并添加到 返回值1 序列中
2、当 参数2 序列中含有句柄时,则将该序列中所有的句柄添加到 返回值2 序列中
3、当 参数3 序列中的句柄发生错误时,则将该发生错误的句柄添加到 返回值3 序列中
4、当 超时时间 未设置,则select会一直阻塞,直到监听的句柄发生变化
5、当 超时时间 = 1时,那么如果监听的句柄均无任何变化,则select会阻塞 1 秒,之后返回三个空列表,如果监听的句柄有变化,则直接执行。

利用select监听终端操作实例

import socket
import select


sk1 = socket.socket()
sk1.bind(("127.0.0.1",8001))
sk1.listen()

sk2 = socket.socket()
sk2.bind(("127.0.0.1",8002))
sk2.listen()

sk3 = socket.socket()
sk3.bind(("127.0.0.1",8003))
sk3.listen()

li = [sk1,sk2,sk3]

while True:
    r_list,w_list,e_list = select.select(li,[],[],1) # r_list可变化的
    for line in r_list: 
        conn,address = line.accept()
        conn.sendall(bytes("Hello World !",encoding="utf-8"))

利用select实现伪同时处理多个Socket客户端请求

服务端:
sk1 = socket.socket()
sk1.bind(("127.0.0.1",8001))
sk1.listen()

inpu = [sk1,]

while True:
    r_list,w_list,e_list = select.select(inpu,[],[],1)
    for sk in r_list:
        if sk == sk1:
            conn,address = sk.accept()
            inpu.append(conn)
        else:
            try:
                ret = str(sk.recv(1024),encoding="utf-8")
                sk.sendall(bytes(ret+"hao",encoding="utf-8"))
            except Exception as ex:
                inpu.remove(sk)

客户端
import socket

obj = socket.socket()

obj.connect(('127.0.0.1',8001))

while True:
    inp = input("Please(q\退出):\n>>>")
    obj.sendall(bytes(inp,encoding="utf-8"))
    if inp == "q":
        break
    ret = str(obj.recv(1024),encoding="utf-8")
    print(ret)

利用select实现伪同时处理多个Socket客户端请求读写分离

服务端:
import socket
sk1 = socket.socket()
sk1.bind(("127.0.0.1",8001))
sk1.listen()
inputs = [sk1]
import select
message_dic = {}
outputs = []
while True:

    r_list, w_list, e_list = select.select(inputs,[],inputs,1)
    print("正在监听的socket对象%d" % len(inputs))
    print(r_list)
    for sk1_or_conn in r_list:
        if sk1_or_conn == sk1:
            conn,address = sk1_or_conn.accept()
            inputs.append(conn)
            message_dic[conn] = []
        else:
            try:
                data_bytes = sk1_or_conn.recv(1024)
                data_str = str(data_bytes,encoding="utf-8")
                sk1_or_conn.sendall(bytes(data_str+"好",encoding="utf-8"))
            except Exception as ex:
                inputs.remove(sk1_or_conn)
            else:
                data_str = str(data_bytes,encoding="utf-8")
                message_dic[sk1_or_conn].append(data_str)
                outputs.append(sk1_or_conn)
        for conn in w_list:
            recv_str = message_dic[conn][0]
            del message_dic[conn][0]
            conn.sendall(bytes(recv_str+"好",encoding="utf-8"))
        for sk in e_list:
            inputs.remove(sk)

客户端:
import socket

obj = socket.socket()

obj.connect(('127.0.0.1',8001))

while True:
    inp = input("Please(q\退出):\n>>>")
    obj.sendall(bytes(inp,encoding="utf-8"))
    if inp == "q":
        break
    ret = str(obj.recv(1024),encoding="utf-8")
    print(ret)


3、socketserver


SocketServer内部使用 IO多路复用 以及 “多线程” 和 “多进程” ,从而实现并发处理多个客户端请求的Socket服务端。即:每个客户端请求连接到服务器时,Socket服务端都会在服务器是创建一个“线程”或者“进程” 专门负责处理当前客户端的所有请求。

ThreadingTCPServer

ThreadingTCPServer实现的Soket服务器内部会为每个client创建一个 “线程”,该线程用来和客户端进行交互。

1、ThreadingTCPServer基础

使用ThreadingTCPServer:

  • 创建一个继承自 SocketServer.BaseRequestHandler 的类
  • 类中必须定义一个名称为 handle 的方法
  • 启动ThreadingTCPServer
# 服务端
import  socketserver

class Myserver(socketserver.BaseRequestHandler):

    def handle(self):

        conn = self.request
        conn.sendall(bytes("你好,我是机器人",encoding="utf-8"))
        while True:
            ret_bytes = conn.recv(1024)
            ret_str = str(ret_bytes,encoding="utf-8")
            if ret_str == "q":
                break
            conn.sendall(bytes(ret_str+"你好我好大家好",encoding="utf-8"))

if __name__ == "__main__":
    server = socketserver.ThreadingTCPServer(("127.0.0.1",8080),Myserver)
    server.serve_forever()

############################
# 客户端
import socket

obj = socket.socket()

obj.connect(("127.0.0.1",8080))

ret_bytes = obj.recv(1024)
ret_str = str(ret_bytes,encoding="utf-8")
print(ret_str)

while True:
    inp = input("你好请问您有什么问题? \n >>>")
    if inp == "q":
        obj.sendall(bytes(inp,encoding="utf-8"))
        break
    else:
        obj.sendall(bytes(inp, encoding="utf-8"))
        ret_bytes = obj.recv(1024)
        ret_str = str(ret_bytes,encoding="utf-8")
        print(ret_str)

2、ThreadingTCPServer源码剖析

ThreadingTCPServer的类图关系如下:


内部调用流程为:

  • 启动服务端程序
  • 执行 TCPServer.__init__ 方法,创建服务端Socket对象并绑定 IP 和 端口
  • 执行 BaseServer.__init__ 方法,将自定义的继承自SocketServer.BaseRequestHandler 的类 MyRequestHandle赋值给 self.RequestHandlerClass
  • 执行 BaseServer.server_forever 方法,While 循环一直监听是否有客户端请求到达 ...
  • 当客户端连接到达服务器
  • 执行 ThreadingMixIn.process_request 方法,创建一个 “线程” 用来处理请求
  • 执行 ThreadingMixIn.process_request_thread 方法
  • 执行 BaseServer.finish_request 方法,执行 self.RequestHandlerClass()  即:执行 自定义 MyRequestHandler 的构造方法(自动调用基类BaseRequestHandler的构造方法,在该构造方法中又会调用 MyRequestHandler的handle方法)

# Baseserver
class BaseServer:

    """Base class for server classes.

    Methods for the caller:

    - __init__(server_address, RequestHandlerClass)
    - serve_forever(poll_interval=0.5)
    - shutdown()
    - handle_request()  # if you do not use serve_forever()
    - fileno() -> int   # for select()

    Methods that may be overridden:

    - server_bind()
    - server_activate()
    - get_request() -> request, client_address
    - handle_timeout()
    - verify_request(request, client_address)
    - server_close()
    - process_request(request, client_address)
    - shutdown_request(request)
    - close_request(request)
    - handle_error()

    Methods for derived classes:

    - finish_request(request, client_address)

    Class variables that may be overridden by derived classes or
    instances:

    - timeout
    - address_family
    - socket_type
    - allow_reuse_address

    Instance variables:

    - RequestHandlerClass
    - socket

    """

    timeout = None

    def __init__(self, server_address, RequestHandlerClass):
        """Constructor.  May be extended, do not override."""
        self.server_address = server_address
        self.RequestHandlerClass = RequestHandlerClass
        self.__is_shut_down = threading.Event()
        self.__shutdown_request = False

    def server_activate(self):
        """Called by constructor to activate the server.

        May be overridden.

        """
        pass

    def serve_forever(self, poll_interval=0.5):
        """Handle one request at a time until shutdown.

        Polls for shutdown every poll_interval seconds. Ignores
        self.timeout. If you need to do periodic tasks, do them in
        another thread.
        """
        self.__is_shut_down.clear()
        try:
            while not self.__shutdown_request:
                # XXX: Consider using another file descriptor or
                # connecting to the socket to wake this up instead of
                # polling. Polling reduces our responsiveness to a
                # shutdown request and wastes cpu at all other times.
                r, w, e = _eintr_retry(select.select, [self], [], [],
                                       poll_interval)
                if self in r:
                    self._handle_request_noblock()
        finally:
            self.__shutdown_request = False
            self.__is_shut_down.set()

    def shutdown(self):
        """Stops the serve_forever loop.

        Blocks until the loop has finished. This must be called while
        serve_forever() is running in another thread, or it will
        deadlock.
        """
        self.__shutdown_request = True
        self.__is_shut_down.wait()

    # The distinction between handling, getting, processing and
    # finishing a request is fairly arbitrary.  Remember:
    #
    # - handle_request() is the top-level call.  It calls
    #   select, get_request(), verify_request() and process_request()
    # - get_request() is different for stream or datagram sockets
    # - process_request() is the place that may fork a new process
    #   or create a new thread to finish the request
    # - finish_request() instantiates the request handler class;
    #   this constructor will handle the request all by itself

    def handle_request(self):
        """Handle one request, possibly blocking.

        Respects self.timeout.
        """
        # Support people who used socket.settimeout() to escape
        # handle_request before self.timeout was available.
        timeout = self.socket.gettimeout()
        if timeout is None:
            timeout = self.timeout
        elif self.timeout is not None:
            timeout = min(timeout, self.timeout)
        fd_sets = _eintr_retry(select.select, [self], [], [], timeout)
        if not fd_sets[0]:
            self.handle_timeout()
            return
        self._handle_request_noblock()

    def _handle_request_noblock(self):
        """Handle one request, without blocking.

        I assume that select.select has returned that the socket is
        readable before this function was called, so there should be
        no risk of blocking in get_request().
        """
        try:
            request, client_address = self.get_request()
        except socket.error:
            return
        if self.verify_request(request, client_address):
            try:
                self.process_request(request, client_address)
            except:
                self.handle_error(request, client_address)
                self.shutdown_request(request)

    def handle_timeout(self):
        """Called if no new request arrives within self.timeout.

        Overridden by ForkingMixIn.
        """
        pass

    def verify_request(self, request, client_address):
        """Verify the request.  May be overridden.

        Return True if we should proceed with this request.

        """
        return True

    def process_request(self, request, client_address):
        """Call finish_request.

        Overridden by ForkingMixIn and ThreadingMixIn.

        """
        self.finish_request(request, client_address)
        self.shutdown_request(request)

    def server_close(self):
        """Called to clean-up the server.

        May be overridden.

        """
        pass

    def finish_request(self, request, client_address):
        """Finish one request by instantiating RequestHandlerClass."""
        self.RequestHandlerClass(request, client_address, self)

    def shutdown_request(self, request):
        """Called to shutdown and close an individual request."""
        self.close_request(request)

    def close_request(self, request):
        """Called to clean up an individual request."""
        pass

    def handle_error(self, request, client_address):
        """Handle an error gracefully.  May be overridden.

        The default is to print a traceback and continue.

        """
        print '-'*40
        print 'Exception happened during processing of request from',
        print client_address
        import traceback
        traceback.print_exc() # XXX But this goes to stderr!
        print '-'*40

# TCP server
class TCPServer(BaseServer):

    """Base class for various socket-based server classes.

    Defaults to synchronous IP stream (i.e., TCP).

    Methods for the caller:

    - __init__(server_address, RequestHandlerClass, bind_and_activate=True)
    - serve_forever(poll_interval=0.5)
    - shutdown()
    - handle_request()  # if you don't use serve_forever()
    - fileno() -> int   # for select()

    Methods that may be overridden:

    - server_bind()
    - server_activate()
    - get_request() -> request, client_address
    - handle_timeout()
    - verify_request(request, client_address)
    - process_request(request, client_address)
    - shutdown_request(request)
    - close_request(request)
    - handle_error()

    Methods for derived classes:

    - finish_request(request, client_address)

    Class variables that may be overridden by derived classes or
    instances:

    - timeout
    - address_family
    - socket_type
    - request_queue_size (only for stream sockets)
    - allow_reuse_address

    Instance variables:

    - server_address
    - RequestHandlerClass
    - socket

    """

    address_family = socket.AF_INET

    socket_type = socket.SOCK_STREAM

    request_queue_size = 5

    allow_reuse_address = False

    def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True):
        """Constructor.  May be extended, do not override."""
        BaseServer.__init__(self, server_address, RequestHandlerClass)
        self.socket = socket.socket(self.address_family,
                                    self.socket_type)
        if bind_and_activate:
            try:
                self.server_bind()
                self.server_activate()
            except:
                self.server_close()
                raise

    def server_bind(self):
        """Called by constructor to bind the socket.

        May be overridden.

        """
        if self.allow_reuse_address:
            self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.socket.bind(self.server_address)
        self.server_address = self.socket.getsockname()

    def server_activate(self):
        """Called by constructor to activate the server.

        May be overridden.

        """
        self.socket.listen(self.request_queue_size)

    def server_close(self):
        """Called to clean-up the server.

        May be overridden.

        """
        self.socket.close()

    def fileno(self):
        """Return socket file number.

        Interface required by select().

        """
        return self.socket.fileno()

    def get_request(self):
        """Get the request and client address from the socket.

        May be overridden.

        """
        return self.socket.accept()

    def shutdown_request(self, request):
        """Called to shutdown and close an individual request."""
        try:
            #explicitly shutdown.  socket.close() merely releases
            #the socket and waits for GC to perform the actual close.
            request.shutdown(socket.SHUT_WR)
        except socket.error:
            pass #some platforms may raise ENOTCONN here
        self.close_request(request)

    def close_request(self, request):
        """Called to clean up an individual request."""
        request.close()

# ThreadingMixIn
class ThreadingMixIn:
    """Mix-in class to handle each request in a new thread."""

    # Decides how threads will act upon termination of the
    # main process
    daemon_threads = False

    def process_request_thread(self, request, client_address):
        """Same as in BaseServer but as a thread.

        In addition, exception handling is done here.

        """
        try:
            self.finish_request(request, client_address)
            self.shutdown_request(request)
        except:
            self.handle_error(request, client_address)
            self.shutdown_request(request)

    def process_request(self, request, client_address):
        """Start a new thread to process the request."""
        t = threading.Thread(target = self.process_request_thread,
                             args = (request, client_address))
        t.daemon = self.daemon_threads
        t.start()

# SocketServer.BaseRequestHandler
class BaseRequestHandler:

    """Base class for request handler classes.

    This class is instantiated for each request to be handled.  The
    constructor sets the instance variables request, client_address
    and server, and then calls the handle() method.  To implement a
    specific service, all you need to do is to derive a class which
    defines a handle() method.

    The handle() method can find the request as self.request, the
    client address as self.client_address, and the server (in case it
    needs access to per-server information) as self.server.  Since a
    separate instance is created for each request, the handle() method
    can define arbitrary other instance variariables.

    """

    def __init__(self, request, client_address, server):
        self.request = request
        self.client_address = client_address
        self.server = server
        self.setup()
        try:
            self.handle()
        finally:
            self.finish()

    def setup(self):
        pass

    def handle(self):
        pass

    def finish(self):
        pass

SocketServer的ThreadingTCPServer之所以可以同时处理请求得益于 select 和 Threading 两个东西,其实本质上就是在服务器端为每一个客户端创建一个线程,当前线程用来处理对应客户端的请求,所以,可以支持同时n个客户端链接(长连接)。



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