发布于 2015-10-10 03:26:02 | 238 次阅读 | 评论: 0 | 来源: 网友投递

这里有新鲜出炉的Python教程,程序狗速度看过来!

Python编程语言

Python 是一种面向对象、解释型计算机程序设计语言,由Guido van Rossum于1989年底发明,第一个公开发行版发行于1991年。Python语法简洁而清晰,具有丰富和强大的类库。它常被昵称为胶水语言,它能够把用其他语言制作的各种模块(尤其是C/C++)很轻松地联结在一起。


这篇文章主要介绍了Python实现在线程里运行scrapy的方法,涉及Python线程操作的技巧,非常具有实用价值,需要的朋友可以参考下

本文实例讲述了Python实现在线程里运行scrapy的方法。分享给大家供大家参考。具体如下:

如果你希望在一个写好的程序里调用scrapy,就可以通过下面的代码,让scrapy运行在一个线程里。

"""
Code to run Scrapy crawler in a thread - works on Scrapy 0.8
"""
import threading, Queue
from twisted.internet import reactor
from scrapy.xlib.pydispatch import dispatcher
from scrapy.core.manager import scrapymanager
from scrapy.core.engine import scrapyengine
from scrapy.core import signals
class CrawlerThread(threading.Thread):
  def __init__(self):
    threading.Thread.__init__(self)
    self.running = False
  def run(self):
    self.running = True
    scrapymanager.configure(control_reactor=False)
    scrapymanager.start()
    reactor.run(installSignalHandlers=False)
  def crawl(self, *args):
    if not self.running:
      raise RuntimeError("CrawlerThread not running")
    self._call_and_block_until_signal(signals.spider_closed, 
      scrapymanager.crawl, *args)
  def stop(self):
    reactor.callFromThread(scrapyengine.stop)
  def _call_and_block_until_signal(self, signal, f, *a, **kw):
    q = Queue.Queue()
    def unblock():
      q.put(None)
    dispatcher.connect(unblock, signal=signal)
    reactor.callFromThread(f, *a, **kw)
    q.get()
# Usage example below:
 
import os
os.environ.setdefault('SCRAPY_SETTINGS_MODULE', 'myproject.settings')
from scrapy.xlib.pydispatch import dispatcher
from scrapy.core import signals
from scrapy.conf import settings
from scrapy.crawler import CrawlerThread
settings.overrides['LOG_ENABLED'] = False # avoid log noise
def item_passed(item):
  print "Just scraped item:", item
dispatcher.connect(item_passed, signal=signals.item_passed)
crawler = CrawlerThread()
print "Starting crawler thread..."
crawler.start()
print "Crawling somedomain.com...."
crawler.crawl('somedomain.com) # blocking call
print "Crawling anotherdomain.com..."
crawler.crawl('anotherdomain.com') # blocking call
print "Stopping crawler thread..."
crawler.stop()



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