python网络编程框架twisted学习笔记(2)

接上篇，我们来看看怎么分别用defer和reactor来实现同样的http客户端。

这个是官方文档给的例子，使用了defer： <pre class=python name=code> from pprint import pformat

from twisted.internet import reactor from twisted.internet.defer import Deferred from twisted.internet.protocol import Protocol from twisted.web.client import Agent from twisted.web.http_headers import Headers

class BeginningPrinter(Protocol): def init(self, finished): self.finished = finished self.remaining = 1024 * 10

def dataReceived(self, bytes):
    if self.remaining:
        display = bytes[:self.remaining]
        print 'Some data received:'
        print display
        self.remaining -= len(display)

def connectionLost(self, reason):
    print 'Finished receiving body:', reason.getErrorMessage()
    self.finished.callback(None)

agent = Agent(reactor) d = agent.request( ‘GET’, ‘http://example.com/’, Headers({‘User-Agent’: [‘Twisted Web Client Example’]}), None)

def cbRequest(response): print ‘Response version:’, response.version print ‘Response code:’, response.code print ‘Response phrase:’, response.phrase print ‘Response headers:’ print pformat(list(response.headers.getAllRawHeaders())) finished = Deferred() response.deliverBody(BeginningPrinter(finished)) return finished d.addCallback(cbRequest)

def cbShutdown(ignored): reactor.stop() d.addBoth(cbShutdown)

reactor.run() </pre>

下面是只用reactor实现的例子： <pre class=python name=code> from twisted.internet import protocol, reactor, defer, utils, interfaces from twisted.web import http, client

class HTTPClient(http.HTTPClient): def init(self, fatcory): self._factory = fatcory

def connectionMade(self): 
    print 'connected'
    self.sendCommand('GET', self._factory.url)
    self.sendHeader('User-Agent', 'Twisted Web Client Example')
    self.endHeaders()
    
def handleStatus(self, version, status, message):
    print("%s %s %s\r\n" %(version, status, message))
    
def handleHeader(self, key, val):
    print("%s: %s\r\n" %(key, val))
    
def handleEndHeaders(self):
    print("\r\n")
    
def rawDataReceived(self, data):
    print(data)
    
def handleResponseEnd(self):
    reactor.stop()

class HTTPClientFactory(client.HTTPClientFactory): def init(self, url): client.HTTPClientFactory.init(self, url) self.url = url

def buildProtocol(self, addr):
    return HTTPClient(self)

reactor.connectTCP(‘google.com’, 80, HTTPClientFactory(‘/’))
reactor.run() </pre>

是不是比defer要清晰一点，可能也有其他场景下使用defer要更好点，但是初学可以选择从reactor入手，能更快的熟悉这个框架。