Scrapy框架: middlewares.py设置

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# -*- coding: utf-8 -*-# Define here the models for your spider middleware
#
# See documentation in:
# https://doc.scrapy.org/en/latest/topics/spider-middleware.htmlfrom scrapy import signalsclass DownloadtestSpiderMiddleware(object):
# Not all methods need to be defined. If a method is not defined,
# scrapy acts as if the spider middleware does not modify the
# passed objects. @classmethod
def from_crawler(cls, crawler):
# This method is used by Scrapy to create your spiders.
s = cls()
crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
return s def process_spider_input(self, response, spider):
# Called for each response that goes through the spider
# middleware and into the spider. # Should return None or raise an exception.
return None def process_spider_output(self, response, result, spider):
# Called with the results returned from the Spider, after
# it has processed the response. # Must return an iterable of Request, dict or Item objects.
for i in result:
yield i def process_spider_exception(self, response, exception, spider):
# Called when a spider or process_spider_input() method
# (from other spider middleware) raises an exception. # Should return either None or an iterable of Response, dict
# or Item objects.
pass def process_start_requests(self, start_requests, spider):
# Called with the start requests of the spider, and works
# similarly to the process_spider_output() method, except
# that it doesn’t have a response associated. # Must return only requests (not items).
for r in start_requests:
yield r def spider_opened(self, spider):
spider.logger.info('Spider opened: %s' % spider.name)class DownloadtestDownloaderMiddleware(object):
# Not all methods need to be defined. If a method is not defined,
# scrapy acts as if the downloader middleware does not modify the
# passed objects. @classmethod
def from_crawler(cls, crawler):
# This method is used by Scrapy to create your spiders.
s = cls()
crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
return s def process_request(self, request, spider):
# Called for each request that goes through the downloader
# middleware. # Must either:
# - return None: continue processing this request
# - or return a Response object
# - or return a Request object
# - or raise IgnoreRequest: process_exception() methods of
# installed downloader middleware will be called
return None def process_response(self, request, response, spider):
# Called with the response returned from the downloader. # Must either;
# - return a Response object
# - return a Request object
# - or raise IgnoreRequest
return response def process_exception(self, request, exception, spider):
# Called when a download handler or a process_request()
# (from other downloader middleware) raises an exception. # Must either:
# - return None: continue processing this exception
# - return a Response object: stops process_exception() chain
# - return a Request object: stops process_exception() chain
pass def spider_opened(self, spider):
spider.logger.info('Spider opened: %s' % spider.name)import random#设置请求头
class RandomUA():
def __init__(self):
self.user_agent=[
'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_1) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0.1 Safari/605.1.16',
'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20100101 Firefox/12.0',
'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)'
] def process_request(self, request, spider):
request.headers['User-Agent'] = random.choice(self.user_agent) def process_response(self, request, response, spider):
response.status=201
return response#设置代理
class ProxyMiddleware:
proxy_list=[
"http://127.0.0.1:8080"
# "http://183.91.33.41:80",
# "http://111.29.3.190:80",
# "http://124.156.108.71:82"
] def process_request(self, request, spider):
ip=random.choice(self.proxy_list)
request.meta['proxy']=ip