使用Python的Twisted框架编写简单的网络客户端


Posted in Python onApril 16, 2015

Protocol
  和服务器一样,也是通过该类来实现。先看一个简短的例程:

from twisted.internet.protocol import Protocol
from sys import stdout

class Echo(Protocol):
  def dataReceived(self, data):
    stdout.write(data)

在本程序中,只是简单的将获得的数据输出到标准输出中来显示,还有很多其他的事件没有作出任何响应,下面
有一个回应其他事件的例子:

from twisted.internet.protocol import Protocol

class WelcomeMessage(Protocol):
  def connectionMade(self):
    self.transport.write("Hello server, I am the client!/r/n")
    self.transport.loseConnection()

本协议连接到服务器,发送了一个问候消息,然后关闭了连接。
connectionMade事件通常被用在建立连接的事件发生时触发。关闭连接的时候会触发connectionLost事件函数

(Simple, single-use clients)简单的单用户客户端
  在许多情况下,protocol仅仅是需要连接服务器一次,并且代码仅仅是要获得一个protocol连接的实例。在
这样的情况下,twisted.internet.protocol.ClientCreator提供了一个恰当的API

from twisted.internet import reactor
from twisted.internet.protocol import Protocol, ClientCreator

class Greeter(Protocol):
  def sendMessage(self, msg):
    self.transport.write("MESSAGE %s/n" % msg)

def gotProtocol(p):
  p.sendMessage("Hello")
  reactor.callLater(1, p.sendMessage, "This is sent in a second")
  reactor.callLater(2, p.transport.loseConnection)

c = ClientCreator(reactor, Greeter)
c.connectTCP("localhost", 1234).addCallback(gotProtocol)

ClientFactory(客户工厂)
  ClientFactory负责创建Protocol,并且返回相关事件的连接状态。这样就允许它去做像连接发生错误然后
重新连接的事情。这里有一个ClientFactory的简单例子使用Echo协议并且打印当前的连接状态

from twisted.internet.protocol import Protocol, ClientFactory
from sys import stdout

class Echo(Protocol):
  def dataReceived(self, data):
    stdout.write(data)

class EchoClientFactory(ClientFactory):
  def startedConnecting(self, connector):
    print 'Started to connect.'
  
  def buildProtocol(self, addr):
    print 'Connected.'
    return Echo()
  
  def clientConnectionLost(self, connector, reason):
    print 'Lost connection. Reason:', reason
  
  def clientConnectionFailed(self, connector, reason):
    print 'Connection failed. Reason:', reason

要想将EchoClientFactory连接到服务器,可以使用下面代码:

from twisted.internet import reactor
reactor.connectTCP(host, port, EchoClientFactory())
reactor.run()

注意:clientConnectionFailed是在Connection不能被建立的时候调用,clientConnectionLost是在连接关闭的时候被调用,两个是有区别的。

Reconnection(重新连接)
  许多时候,客户端连接可能由于网络错误经常被断开。一个重新建立连接的方法是在连接断开的时候调用

connector.connect()方法。

from twisted.internet.protocol import ClientFactory

class EchoClientFactory(ClientFactory):
  def clientConnectionLost(self, connector, reason):
    connector.connect()

   connector是connection和protocol之间的一个接口被作为第一个参数传递给clientConnectionLost,

factory能调用connector.connect()方法重新进行连接
   然而,许多程序在连接失败和连接断开进行重新连接的时候使用ReconnectingClientFactory函数代替这个

函数,并且不断的尝试重新连接。这里有一个Echo Protocol使用ReconnectingClientFactory的例子:

from twisted.internet.protocol import Protocol, ReconnectingClientFactory
from sys import stdout

class Echo(Protocol):
  def dataReceived(self, data):
    stdout.write(data)

class EchoClientFactory(ReconnectingClientFactory):
  def startedConnecting(self, connector):
    print 'Started to connect.'

  def buildProtocol(self, addr):
    print 'Connected.'
    print 'Resetting reconnection delay'
    self.resetDelay()
    return Echo()

  def clientConnectionLost(self, connector, reason):
    print 'Lost connection. Reason:', reason
    ReconnectingClientFactory.clientConnectionLost(self, connector, reason)

  def clientConnectionFailed(self, connector, reason):
    print 'Connection failed. Reason:', reason
    ReconnectingClientFactory.clientConnectionFailed(self, connector,reason)

A Higher-Level Example: ircLogBot
上面的所有例子都非常简单,下面是一个比较复杂的例子来自于doc/examples目录

# twisted imports
from twisted.words.protocols import irc
from twisted.internet import reactor, protocol
from twisted.python import log

# system imports
import time, sys


class MessageLogger:
  """
  An independent logger class (because separation of application
  and protocol logic is a good thing).
  """
  def __init__(self, file):
    self.file = file

  def log(self, message):
    """Write a message to the file."""
    timestamp = time.strftime("[%H:%M:%S]", time.localtime(time.time()))
    self.file.write('%s %s/n' % (timestamp, message))
    self.file.flush()

  def close(self):
    self.file.close()


class LogBot(irc.IRCClient):
  """A logging IRC bot."""

  nickname = "twistedbot"

  def connectionMade(self):
    irc.IRCClient.connectionMade(self)
    self.logger = MessageLogger(open(self.factory.filename, "a"))
    self.logger.log("[connected at %s]" %
            time.asctime(time.localtime(time.time())))

  def connectionLost(self, reason):
    irc.IRCClient.connectionLost(self, reason)
    self.logger.log("[disconnected at %s]" %
            time.asctime(time.localtime(time.time())))
    self.logger.close()


  # callbacks for events

  def signedOn(self):
    """Called when bot has succesfully signed on to server."""
    self.join(self.factory.channel)

  def joined(self, channel):
    """This will get called when the bot joins the channel."""
    self.logger.log("[I have joined %s]" % channel)

  def privmsg(self, user, channel, msg):
    """This will get called when the bot receives a message."""
    user = user.split('!', 1)[0]
    self.logger.log("<%s> %s" % (user, msg))

    # Check to see if they're sending me a private message
    if channel == self.nickname:
      msg = "It isn't nice to whisper! Play nice with the group."
      self.msg(user, msg)
      return

    # Otherwise check to see if it is a message directed at me
    if msg.startswith(self.nickname + ":"):
      msg = "%s: I am a log bot" % user
      self.msg(channel, msg)
      self.logger.log("<%s> %s" % (self.nickname, msg))

  def action(self, user, channel, msg):
    """This will get called when the bot sees someone do an action."""
    user = user.split('!', 1)[0]
    self.logger.log("* %s %s" % (user, msg))

  # irc callbacks

  def irc_NICK(self, prefix, params):
    """Called when an IRC user changes their nickname."""
    old_nick = prefix.split('!')[0]
    new_nick = params[0]
    self.logger.log("%s is now known as %s" % (old_nick, new_nick))


class LogBotFactory(protocol.ClientFactory):
  """A factory for LogBots.

  A new protocol instance will be created each time we connect to the server.
  """

  # the class of the protocol to build when new connection is made
  protocol = LogBot

  def __init__(self, channel, filename):
    self.channel = channel
    self.filename = filename

  def clientConnectionLost(self, connector, reason):
    """If we get disconnected, reconnect to server."""
    connector.connect()

  def clientConnectionFailed(self, connector, reason):
    print "connection failed:", reason
    reactor.stop()


if __name__ == '__main__':
  # initialize logging
  log.startLogging(sys.stdout)

  # create factory protocol and application
  f = LogBotFactory(sys.argv[1], sys.argv[2])

  # connect factory to this host and port
  reactor.connectTCP("irc.freenode.net", 6667, f)

  # run bot
  reactor.run()

ircLogBot.py 连接到了IRC服务器,加入了一个频道,并且在文件中记录了所有的通信信息,这表明了在断开连接进行重新连接的连接级别的逻辑以及持久性数据是被存储在Factory的。

Persistent Data in the Factory
  由于Protocol在每次连接的时候重建,客户端需要以某种方式来记录数据以保证持久化。就好像日志机器人一样他需要知道那个那个频道正在登陆,登陆到什么地方去。

from twisted.internet import protocol
from twisted.protocols import irc

class LogBot(irc.IRCClient):

  def connectionMade(self):
    irc.IRCClient.connectionMade(self)
    self.logger = MessageLogger(open(self.factory.filename, "a"))
    self.logger.log("[connected at %s]" %
            time.asctime(time.localtime(time.time())))
  
  def signedOn(self):
    self.join(self.factory.channel)

  
class LogBotFactory(protocol.ClientFactory):
  
  protocol = LogBot
  
  def __init__(self, channel, filename):
    self.channel = channel
    self.filename = filename

当protocol被创建之后,factory会获得他本身的一个实例的引用。然后,就能够在factory中存在他的属性。

更多的信息:
  本文档讲述的Protocol类是IProtocol的子类,IProtocol方便的被应用在大量的twisted应用程序中。要学习完整的 IProtocol接口,请参考API文档IProtocol.
  在本文档一些例子中使用的trasport属性提供了ITCPTransport接口,要学习完整的接口,请参考API文档ITCPTransport
  接口类是指定对象有什么方法和属性以及他们的表现形式的一种方法。参考 Components: Interfaces and Adapters文档

Python 相关文章推荐
python实现爬虫下载漫画示例
Feb 16 Python
Python开发的单词频率统计工具wordsworth使用方法
Jun 25 Python
Python实现的一个自动售饮料程序代码分享
Aug 25 Python
Python程序退出方式小结
Dec 09 Python
Python实现的根据文件名查找数据文件功能示例
May 02 Python
flask-restful使用总结
Dec 04 Python
对python中dict和json的区别详解
Dec 18 Python
使用Windows批处理和WMI设置Python的环境变量方法
Aug 14 Python
python orm 框架中sqlalchemy用法实例详解
Feb 02 Python
Python自带的IDE在哪里
Jul 01 Python
Python基础之条件语句详解
Jun 16 Python
利用For循环遍历Python字典的三种方法实例
Mar 25 Python
从Python的源码浅要剖析Python的内存管理
Apr 16 #Python
用Python实现换行符转换的脚本的教程
Apr 16 #Python
Python下的subprocess模块的入门指引
Apr 16 #Python
Python下的twisted框架入门指引
Apr 15 #Python
Python代码调试的几种方法总结
Apr 15 #Python
详解Python中with语句的用法
Apr 15 #Python
python获取本机外网ip的方法
Apr 15 #Python
You might like
PHP 使用header函数设置HTTP头的示例解析 表头
2013/06/17 PHP
Codeigniter中禁止A Database Error Occurred错误提示的方法
2014/06/12 PHP
php过滤html标记属性类用法实例
2014/09/23 PHP
js 匿名调用实现代码
2009/06/19 Javascript
JavaScript实现QueryString获取GET参数的方法
2013/07/02 Javascript
如何正确使用javascript 来进行我们的程序开发
2014/06/23 Javascript
JavaScript 变量、作用域及内存
2015/04/08 Javascript
jQuery中extend函数详解
2015/07/13 Javascript
Bootstrap实现默认导航栏效果
2020/09/21 Javascript
JavaScript导航脚本判断当前导航
2016/07/12 Javascript
BootStrap中Table分页插件使用详解
2016/10/09 Javascript
浅析JS中的 map, filter, some, every, forEach, for in, for of 用法总结
2017/03/29 Javascript
js图片放大镜效果实现方法详解
2020/10/28 Javascript
基于Vuejs的搜索匹配功能实现方法
2018/03/03 Javascript
Vue触发式全局组件构建的方法
2018/11/28 Javascript
JavaScript JMap类定义与使用方法示例
2019/01/22 Javascript
[48:00]EG vs LGD 2018国际邀请赛淘汰赛BO3 第二场 8.26
2018/08/29 DOTA
低版本中Python除法运算小技巧
2015/04/05 Python
linux下python使用sendmail发送邮件
2018/05/22 Python
Python利用heapq实现一个优先级队列的方法
2019/02/03 Python
pandas条件组合筛选和按范围筛选的示例代码
2019/08/26 Python
Python编译成.so文件进行加密后调用的实现
2019/12/23 Python
Python实现的北京积分落户数据分析示例
2020/03/27 Python
Python绘制组合图的示例
2020/09/18 Python
Ralph Lauren法国官网:美国高品味时装品牌
2017/12/08 全球购物
SmartBuyGlasses英国:购买太阳镜和眼镜
2018/01/29 全球购物
商务专员岗位职责
2013/11/23 职场文书
学生感冒英文请假条
2014/02/04 职场文书
计算机网络工程专业职业生涯规划书
2014/03/10 职场文书
最新结婚典礼主持词
2014/03/14 职场文书
学习群众路线的心得体会
2014/11/05 职场文书
2015年感恩母亲节的演讲稿
2015/03/18 职场文书
小学四年级班主任工作经验交流材料
2015/11/02 职场文书
六年级语文教学反思
2016/03/03 职场文书
Python面向对象之内置函数相关知识总结
2021/06/24 Python
VMware虚拟机安装 Windows Server 2022的详细图文教程
2022/09/23 Servers