一、异步非阻塞

  1.自定义异步非阻塞

 import socket
import select class Request(object):
def __init__(self,sock,func,url):
self.sock = sock
self.func = func
self.url = url def fileno(self):
return self.sock.fileno() def async_request(url_list): input_list = []
conn_list = [] for url in url_list:
client = socket.socket()
client.setblocking(False)
# 创建连接,不阻塞
try:
client.connect((url[],,)) # 100个向百度发送的请求
except BlockingIOError as e:
pass obj = Request(client,url[],url[]) input_list.append(obj)
conn_list.append(obj) while True:
# 监听socket是否已经发生变化 [request_obj,request_obj....request_obj]
# 如果有请求连接成功:wlist = [request_obj,request_obj]
# 如果有响应的数据: rlist = [request_obj,request_obj....client100]
rlist,wlist,elist = select.select(input_list,conn_list,[],0.05)
for request_obj in wlist:
# print('连接成功')
# # # # 发送Http请求
# print('发送请求')
request_obj.sock.sendall("GET / HTTP/1.0\r\nhost:{0}\r\n\r\n".format(request_obj.url).encode('utf-8'))
conn_list.remove(request_obj) for request_obj in rlist:
data = request_obj.sock.recv()
request_obj.func(data)
request_obj.sock.close()
input_list.remove(request_obj) if not input_list:
break

  2. 调用上面自定义模块

 import s2

 def callback1(data):
print('百度回来了',data) def callback2(data):
print('必应回来了',data) url_list = [
['www.baidu.com',callback1],
['www.bing.com',callback2]
]
s2.async_request(url_list) # ################################# twisted #################################
from twisted.web.client import getPage, defer
from twisted.internet import reactor def all_done(arg):
reactor.stop() def callback1(contents):
print(contents) def callback2(contents):
print(contents)
deferred_list = [] url_list = [
('http://www.bing.com',callback1),
('http://www.baidu.com',callback2)
]
for url in url_list:
deferred = getPage(bytes(url[0], encoding='utf8'))
deferred.addCallback(url[1])
deferred_list.append(deferred) dlist = defer.DeferredList(deferred_list)
dlist.addBoth(all_done)

二、scrapy

  

  1. 安装

pip3 install scrapy

  2. 基本命令

1. scrapy startproject p1
2. scrapy genspider chouti chouti.com
3. scrapy list
4. scrapy crawl chouti

  3. 项目文件介绍

scrapy.cfg  项目的主配置信息。(真正爬虫相关的配置信息在settings.py文件中)
items.py 设置数据存储模板,用于结构化数据,如:Django的Model
pipelines 数据处理行为,如:一般结构化的数据持久化
settings.py 配置文件,如:递归的层数、并发数,延迟下载等
spiders 爬虫目录,如:创建文件,编写爬虫规则

  4. 小试牛刀

 import scrapy
from scrapy.selector import HtmlXPathSelector
from scrapy.http.request import Request class DigSpider(scrapy.Spider):
# 爬虫应用的名称,通过此名称启动爬虫命令
name = "dig" # 允许的域名
allowed_domains = ["chouti.com"] # 起始URL
start_urls = [
'http://dig.chouti.com/',
] has_request_set = {} def parse(self, response):
print(response.url) hxs = HtmlXPathSelector(response)
page_list = hxs.select('//div[@id="dig_lcpage"]//a[re:test(@href, "/all/hot/recent/\d+")]/@href').extract()
for page in page_list:
page_url = 'http://dig.chouti.com%s' % page
key = self.md5(page_url)
if key in self.has_request_set:
pass
else:
self.has_request_set[key] = page_url
obj = Request(url=page_url, method='GET', callback=self.parse)
yield obj @staticmethod
def md5(val):
import hashlib
ha = hashlib.md5()
ha.update(bytes(val, encoding='utf-8'))
key = ha.hexdigest()
return key

  运行:scrapy crawl chouti.com --nolog

  5. 选择器

 from scrapy.selector import Selector, HtmlXPathSelector
from scrapy.http import HtmlResponse
html = """<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
</head>
<body>
<ul>
<li class="item-"><a id='i1' href="link.html">first item</a></li>
<li class="item-0"><a id='i2' href="llink.html">first item</a></li>
<li class="item-1"><a href="llink2.html">second item<span>vv</span></a></li>
</ul>
<div><a href="llink2.html">second item</a></div>
</body>
</html>
"""
response = HtmlResponse(url='http://example.com', body=html,encoding='utf-8')
# hxs = HtmlXPathSelector(response)
# print(hxs)
# hxs = Selector(response=response).xpath('//a')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[2]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@id]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@id="i1"]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@href="link.html"][@id="i1"]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[contains(@href, "link")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[starts-with(@href, "link")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]/text()').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]/@href').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('/html/body/ul/li/a/@href').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('//body/ul/li/a/@href').extract_first()
# print(hxs) # ul_list = Selector(response=response).xpath('//body/ul/li')
# for item in ul_list:
# v = item.xpath('./a/span')
# # 或
# # v = item.xpath('a/span')
# # 或
# # v = item.xpath('*/a/span')
# print(v)
 import scrapy
from scrapy.selector import HtmlXPathSelector
from scrapy.http.request import Request
from scrapy.http.cookies import CookieJar
from scrapy import FormRequest class ChouTiSpider(scrapy.Spider):
# 爬虫应用的名称,通过此名称启动爬虫命令
name = "chouti"
# 允许的域名
allowed_domains = ["chouti.com"] cookie_dict = {}
has_request_set = {} def start_requests(self):
url = 'http://dig.chouti.com/'
# return [Request(url=url, callback=self.login)]
yield Request(url=url, callback=self.login) def login(self, response):
cookie_jar = CookieJar()
cookie_jar.extract_cookies(response, response.request)
for k, v in cookie_jar._cookies.items():
for i, j in v.items():
for m, n in j.items():
self.cookie_dict[m] = n.value req = Request(
url='http://dig.chouti.com/login',
method='POST',
headers={'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'},
body='phone=8615131255089&password=pppppppp&oneMonth=1',
cookies=self.cookie_dict,
callback=self.check_login
)
yield req def check_login(self, response):
req = Request(
url='http://dig.chouti.com/',
method='GET',
callback=self.show,
cookies=self.cookie_dict,
dont_filter=True
)
yield req def show(self, response):
# print(response)
hxs = HtmlXPathSelector(response)
news_list = hxs.select('//div[@id="content-list"]/div[@class="item"]')
for new in news_list:
# temp = new.xpath('div/div[@class="part2"]/@share-linkid').extract()
link_id = new.xpath('*/div[@class="part2"]/@share-linkid').extract_first()
yield Request(
url='http://dig.chouti.com/link/vote?linksId=%s' %(link_id,),
method='POST',
cookies=self.cookie_dict,
callback=self.do_favor
) page_list = hxs.select('//div[@id="dig_lcpage"]//a[re:test(@href, "/all/hot/recent/\d+")]/@href').extract()
for page in page_list: page_url = 'http://dig.chouti.com%s' % page
import hashlib
hash = hashlib.md5()
hash.update(bytes(page_url,encoding='utf-8'))
key = hash.hexdigest()
if key in self.has_request_set:
pass
else:
self.has_request_set[key] = page_url
yield Request(
url=page_url,
method='GET',
callback=self.show
) def do_favor(self, response):
print(response.text)

自动登录抽屉点赞

  6. 格式化处理

spider/xiahuar.py
 import scrapy

 class XiaoHuarItem(scrapy.Item):
name = scrapy.Field()
school = scrapy.Field()
url = scrapy.Field()

items

 import json
import os
import requests class JsonPipeline(object):
def __init__(self):
self.file = open('xiaohua.txt', 'w') def process_item(self, item, spider):
v = json.dumps(dict(item), ensure_ascii=False)
self.file.write(v)
self.file.write('\n')
self.file.flush()
return item class FilePipeline(object):
def __init__(self):
if not os.path.exists('imgs'):
os.makedirs('imgs') def process_item(self, item, spider):
response = requests.get(item['url'], stream=True)
file_name = '%s_%s.jpg' % (item['name'], item['school'])
with open(os.path.join('imgs', file_name), mode='wb') as f:
f.write(response.content)
return item

pipelines

 ITEM_PIPELINES = {
'spider1.pipelines.JsonPipeline': 100,
'spider1.pipelines.FilePipeline': 300,
}
# 每行后面的整型值,确定了他们运行的顺序,item按数字从低到高的顺序,通过pipeline,通常将这些数字定义在0-1000范围内。

settings

  7. 自定义pipelines

 from scrapy.exceptions import DropItem

 class CustomPipeline(object):
def __init__(self,v):
self.value = v def process_item(self, item, spider):
# 操作并进行持久化 # return表示会被后续的pipeline继续处理
return item # 表示将item丢弃,不会被后续pipeline处理
# raise DropItem() @classmethod
def from_crawler(cls, crawler):
"""
初始化时候,用于创建pipeline对象
:param crawler:
:return:
"""
val = crawler.settings.getint('MMMM')
return cls(val) def open_spider(self,spider):
"""
爬虫开始执行时,调用
:param spider:
:return:
"""
print('') def close_spider(self,spider):
"""
爬虫关闭时,被调用
:param spider:
:return:
"""
print('') 自定义pipeline

  8. 中间件  

 class SpiderMiddleware(object):

     def process_spider_input(self,response, spider):
"""
下载完成,执行,然后交给parse处理
:param response:
:param spider:
:return:
"""
pass def process_spider_output(self,response, result, spider):
"""
spider处理完成,返回时调用
:param response:
:param result:
:param spider:
:return: 必须返回包含 Request 或 Item 对象的可迭代对象(iterable)
"""
return result def process_spider_exception(self,response, exception, spider):
"""
异常调用
:param response:
:param exception:
:param spider:
:return: None,继续交给后续中间件处理异常;含 Response 或 Item 的可迭代对象(iterable),交给调度器或pipeline
"""
return None def process_start_requests(self,start_requests, spider):
"""
爬虫启动时调用
:param start_requests:
:param spider:
:return: 包含 Request 对象的可迭代对象
"""
return start_requests 爬虫中间件

爬虫中间件

 class DownMiddleware1(object):
def process_request(self, request, spider):
"""
请求需要被下载时,经过所有下载器中间件的process_request调用
:param request:
:param spider:
:return:
None,继续后续中间件去下载;
Response对象,停止process_request的执行,开始执行process_response
Request对象,停止中间件的执行,将Request重新调度器
raise IgnoreRequest异常,停止process_request的执行,开始执行process_exception
"""
pass def process_response(self, request, response, spider):
"""
spider处理完成,返回时调用
:param response:
:param result:
:param spider:
:return:
Response 对象:转交给其他中间件process_response
Request 对象:停止中间件,request会被重新调度下载
raise IgnoreRequest 异常:调用Request.errback
"""
print('response1')
return response def process_exception(self, request, exception, spider):
"""
当下载处理器(download handler)或 process_request() (下载中间件)抛出异常
:param response:
:param exception:
:param spider:
:return:
None:继续交给后续中间件处理异常;
Response对象:停止后续process_exception方法
Request对象:停止中间件,request将会被重新调用下载
"""
return None 下载器中间件

下载中间件

  9. 自定制命令

  A.在spiders同级创建任意目录,在目录创建crawlall.py

 from scrapy.commands import ScrapyCommand
from scrapy.utils.project import get_project_settings class Command(ScrapyCommand): requires_project = True def syntax(self):
return '[options]' def short_desc(self):
return 'Runs all of the spiders' def run(self, args, opts):
spider_list = self.crawler_process.spiders.list()
for name in spider_list:
self.crawler_process.crawl(name, **opts.__dict__)
self.crawler_process.start()

crawlall.py

  B.在settings.py 中添加配置 COMMANDS_MODULE = '项目名称.目录名称

  C.scrapy crawlall

 

  10. 避免重复访问

    scrapy默认使用 scrapy.dupefilter.RFPDupeFilter 进行去重,相关配置有:

DUPEFILTER_CLASS = 'scrapy.dupefilter.RFPDupeFilter'
DUPEFILTER_DEBUG = False
JOBDIR = "保存范文记录的日志路径,如:/root/" # 最终路径为 /root/requests.seen

  11. settings其它配置

 # -*- coding: utf-8 -*-

 # Scrapy settings for step8_king project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
# http://doc.scrapy.org/en/latest/topics/settings.html
# http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
# http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html # 1. 爬虫名称
BOT_NAME = 'step8_king' # 2. 爬虫应用路径
SPIDER_MODULES = ['step8_king.spiders']
NEWSPIDER_MODULE = 'step8_king.spiders' # Crawl responsibly by identifying yourself (and your website) on the user-agent
# 3. 客户端 user-agent请求头
# USER_AGENT = 'step8_king (+http://www.yourdomain.com)' # Obey robots.txt rules
# 4. 禁止爬虫配置
# ROBOTSTXT_OBEY = False # Configure maximum concurrent requests performed by Scrapy (default: 16)
# 5. 并发请求数
# CONCURRENT_REQUESTS = 4 # Configure a delay for requests for the same website (default: 0)
# See http://scrapy.readthedocs.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
# 6. 延迟下载秒数
# DOWNLOAD_DELAY = 2 # The download delay setting will honor only one of:
# 7. 单域名访问并发数,并且延迟下次秒数也应用在每个域名
# CONCURRENT_REQUESTS_PER_DOMAIN = 2
# 单IP访问并发数,如果有值则忽略:CONCURRENT_REQUESTS_PER_DOMAIN,并且延迟下次秒数也应用在每个IP
# CONCURRENT_REQUESTS_PER_IP = 3 # Disable cookies (enabled by default)
# 8. 是否支持cookie,cookiejar进行操作cookie
# COOKIES_ENABLED = True
# COOKIES_DEBUG = True # Disable Telnet Console (enabled by default)
# 9. Telnet用于查看当前爬虫的信息,操作爬虫等...
# 使用telnet ip port ,然后通过命令操作
# TELNETCONSOLE_ENABLED = True
# TELNETCONSOLE_HOST = '127.0.0.1'
# TELNETCONSOLE_PORT = [6023,] # 10. 默认请求头
# Override the default request headers:
# DEFAULT_REQUEST_HEADERS = {
# 'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
# 'Accept-Language': 'en',
# } # Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
# 11. 定义pipeline处理请求
# ITEM_PIPELINES = {
# 'step8_king.pipelines.JsonPipeline': 700,
# 'step8_king.pipelines.FilePipeline': 500,
# } # 12. 自定义扩展,基于信号进行调用
# Enable or disable extensions
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html
# EXTENSIONS = {
# # 'step8_king.extensions.MyExtension': 500,
# } # 13. 爬虫允许的最大深度,可以通过meta查看当前深度;0表示无深度
# DEPTH_LIMIT = 3 # 14. 爬取时,0表示深度优先Lifo(默认);1表示广度优先FiFo # 后进先出,深度优先
# DEPTH_PRIORITY = 0
# SCHEDULER_DISK_QUEUE = 'scrapy.squeue.PickleLifoDiskQueue'
# SCHEDULER_MEMORY_QUEUE = 'scrapy.squeue.LifoMemoryQueue'
# 先进先出,广度优先 # DEPTH_PRIORITY = 1
# SCHEDULER_DISK_QUEUE = 'scrapy.squeue.PickleFifoDiskQueue'
# SCHEDULER_MEMORY_QUEUE = 'scrapy.squeue.FifoMemoryQueue' # 15. 调度器队列
# SCHEDULER = 'scrapy.core.scheduler.Scheduler'
# from scrapy.core.scheduler import Scheduler # 16. 访问URL去重
# DUPEFILTER_CLASS = 'step8_king.duplication.RepeatUrl' # Enable and configure the AutoThrottle extension (disabled by default)
# See http://doc.scrapy.org/en/latest/topics/autothrottle.html """
17. 自动限速算法
from scrapy.contrib.throttle import AutoThrottle
自动限速设置
1. 获取最小延迟 DOWNLOAD_DELAY
2. 获取最大延迟 AUTOTHROTTLE_MAX_DELAY
3. 设置初始下载延迟 AUTOTHROTTLE_START_DELAY
4. 当请求下载完成后,获取其"连接"时间 latency,即:请求连接到接受到响应头之间的时间
5. 用于计算的... AUTOTHROTTLE_TARGET_CONCURRENCY
target_delay = latency / self.target_concurrency
new_delay = (slot.delay + target_delay) / 2.0 # 表示上一次的延迟时间
new_delay = max(target_delay, new_delay)
new_delay = min(max(self.mindelay, new_delay), self.maxdelay)
slot.delay = new_delay
""" # 开始自动限速
# AUTOTHROTTLE_ENABLED = True
# The initial download delay
# 初始下载延迟
# AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
# 最大下载延迟
# AUTOTHROTTLE_MAX_DELAY = 10
# The average number of requests Scrapy should be sending in parallel to each remote server
# 平均每秒并发数
# AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0 # Enable showing throttling stats for every response received:
# 是否显示
# AUTOTHROTTLE_DEBUG = True # Enable and configure HTTP caching (disabled by default)
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings """
18. 启用缓存
目的用于将已经发送的请求或相应缓存下来,以便以后使用 from scrapy.downloadermiddlewares.httpcache import HttpCacheMiddleware
from scrapy.extensions.httpcache import DummyPolicy
from scrapy.extensions.httpcache import FilesystemCacheStorage
"""
# 是否启用缓存策略
# HTTPCACHE_ENABLED = True # 缓存策略:所有请求均缓存,下次在请求直接访问原来的缓存即可
# HTTPCACHE_POLICY = "scrapy.extensions.httpcache.DummyPolicy"
# 缓存策略:根据Http响应头:Cache-Control、Last-Modified 等进行缓存的策略
# HTTPCACHE_POLICY = "scrapy.extensions.httpcache.RFC2616Policy" # 缓存超时时间
# HTTPCACHE_EXPIRATION_SECS = 0 # 缓存保存路径
# HTTPCACHE_DIR = 'httpcache' # 缓存忽略的Http状态码
# HTTPCACHE_IGNORE_HTTP_CODES = [] # 缓存存储的插件
# HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage' """
19. 代理,需要在环境变量中设置
from scrapy.contrib.downloadermiddleware.httpproxy import HttpProxyMiddleware 方式一:使用默认
os.environ
{
http_proxy:http://root:woshiniba@192.168.11.11:9999/
https_proxy:http://192.168.11.11:9999/
}
方式二:使用自定义下载中间件 def to_bytes(text, encoding=None, errors='strict'):
if isinstance(text, bytes):
return text
if not isinstance(text, six.string_types):
raise TypeError('to_bytes must receive a unicode, str or bytes '
'object, got %s' % type(text).__name__)
if encoding is None:
encoding = 'utf-8'
return text.encode(encoding, errors) class ProxyMiddleware(object):
def process_request(self, request, spider):
PROXIES = [
{'ip_port': '111.11.228.75:80', 'user_pass': ''},
{'ip_port': '120.198.243.22:80', 'user_pass': ''},
{'ip_port': '111.8.60.9:8123', 'user_pass': ''},
{'ip_port': '101.71.27.120:80', 'user_pass': ''},
{'ip_port': '122.96.59.104:80', 'user_pass': ''},
{'ip_port': '122.224.249.122:8088', 'user_pass': ''},
]
proxy = random.choice(PROXIES)
if proxy['user_pass'] is not None:
request.meta['proxy'] = to_bytes("http://%s" % proxy['ip_port'])
encoded_user_pass = base64.encodestring(to_bytes(proxy['user_pass']))
request.headers['Proxy-Authorization'] = to_bytes('Basic ' + encoded_user_pass)
print "**************ProxyMiddleware have pass************" + proxy['ip_port']
else:
print "**************ProxyMiddleware no pass************" + proxy['ip_port']
request.meta['proxy'] = to_bytes("http://%s" % proxy['ip_port']) DOWNLOADER_MIDDLEWARES = {
'step8_king.middlewares.ProxyMiddleware': 500,
} """ """
20. Https访问
Https访问时有两种情况:
1. 要爬取网站使用的可信任证书(默认支持)
DOWNLOADER_HTTPCLIENTFACTORY = "scrapy.core.downloader.webclient.ScrapyHTTPClientFactory"
DOWNLOADER_CLIENTCONTEXTFACTORY = "scrapy.core.downloader.contextfactory.ScrapyClientContextFactory" 2. 要爬取网站使用的自定义证书
DOWNLOADER_HTTPCLIENTFACTORY = "scrapy.core.downloader.webclient.ScrapyHTTPClientFactory"
DOWNLOADER_CLIENTCONTEXTFACTORY = "step8_king.https.MySSLFactory" # https.py
from scrapy.core.downloader.contextfactory import ScrapyClientContextFactory
from twisted.internet.ssl import (optionsForClientTLS, CertificateOptions, PrivateCertificate) class MySSLFactory(ScrapyClientContextFactory):
def getCertificateOptions(self):
from OpenSSL import crypto
v1 = crypto.load_privatekey(crypto.FILETYPE_PEM, open('/Users/wupeiqi/client.key.unsecure', mode='r').read())
v2 = crypto.load_certificate(crypto.FILETYPE_PEM, open('/Users/wupeiqi/client.pem', mode='r').read())
return CertificateOptions(
privateKey=v1, # pKey对象
certificate=v2, # X509对象
verify=False,
method=getattr(self, 'method', getattr(self, '_ssl_method', None))
)
其他:
相关类
scrapy.core.downloader.handlers.http.HttpDownloadHandler
scrapy.core.downloader.webclient.ScrapyHTTPClientFactory
scrapy.core.downloader.contextfactory.ScrapyClientContextFactory
相关配置
DOWNLOADER_HTTPCLIENTFACTORY
DOWNLOADER_CLIENTCONTEXTFACTORY """ """
21. 爬虫中间件
class SpiderMiddleware(object): def process_spider_input(self,response, spider):
'''
下载完成,执行,然后交给parse处理
:param response:
:param spider:
:return:
'''
pass def process_spider_output(self,response, result, spider):
'''
spider处理完成,返回时调用
:param response:
:param result:
:param spider:
:return: 必须返回包含 Request 或 Item 对象的可迭代对象(iterable)
'''
return result def process_spider_exception(self,response, exception, spider):
'''
异常调用
:param response:
:param exception:
:param spider:
:return: None,继续交给后续中间件处理异常;含 Response 或 Item 的可迭代对象(iterable),交给调度器或pipeline
'''
return None def process_start_requests(self,start_requests, spider):
'''
爬虫启动时调用
:param start_requests:
:param spider:
:return: 包含 Request 对象的可迭代对象
'''
return start_requests 内置爬虫中间件:
'scrapy.contrib.spidermiddleware.httperror.HttpErrorMiddleware': 50,
'scrapy.contrib.spidermiddleware.offsite.OffsiteMiddleware': 500,
'scrapy.contrib.spidermiddleware.referer.RefererMiddleware': 700,
'scrapy.contrib.spidermiddleware.urllength.UrlLengthMiddleware': 800,
'scrapy.contrib.spidermiddleware.depth.DepthMiddleware': 900, """
# from scrapy.contrib.spidermiddleware.referer import RefererMiddleware
# Enable or disable spider middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
SPIDER_MIDDLEWARES = {
# 'step8_king.middlewares.SpiderMiddleware': 543,
} """
22. 下载中间件
class DownMiddleware1(object):
def process_request(self, request, spider):
'''
请求需要被下载时,经过所有下载器中间件的process_request调用
:param request:
:param spider:
:return:
None,继续后续中间件去下载;
Response对象,停止process_request的执行,开始执行process_response
Request对象,停止中间件的执行,将Request重新调度器
raise IgnoreRequest异常,停止process_request的执行,开始执行process_exception
'''
pass def process_response(self, request, response, spider):
'''
spider处理完成,返回时调用
:param response:
:param result:
:param spider:
:return:
Response 对象:转交给其他中间件process_response
Request 对象:停止中间件,request会被重新调度下载
raise IgnoreRequest 异常:调用Request.errback
'''
print('response1')
return response def process_exception(self, request, exception, spider):
'''
当下载处理器(download handler)或 process_request() (下载中间件)抛出异常
:param response:
:param exception:
:param spider:
:return:
None:继续交给后续中间件处理异常;
Response对象:停止后续process_exception方法
Request对象:停止中间件,request将会被重新调用下载
'''
return None 默认下载中间件
{
'scrapy.contrib.downloadermiddleware.robotstxt.RobotsTxtMiddleware': 100,
'scrapy.contrib.downloadermiddleware.httpauth.HttpAuthMiddleware': 300,
'scrapy.contrib.downloadermiddleware.downloadtimeout.DownloadTimeoutMiddleware': 350,
'scrapy.contrib.downloadermiddleware.useragent.UserAgentMiddleware': 400,
'scrapy.contrib.downloadermiddleware.retry.RetryMiddleware': 500,
'scrapy.contrib.downloadermiddleware.defaultheaders.DefaultHeadersMiddleware': 550,
'scrapy.contrib.downloadermiddleware.redirect.MetaRefreshMiddleware': 580,
'scrapy.contrib.downloadermiddleware.httpcompression.HttpCompressionMiddleware': 590,
'scrapy.contrib.downloadermiddleware.redirect.RedirectMiddleware': 600,
'scrapy.contrib.downloadermiddleware.cookies.CookiesMiddleware': 700,
'scrapy.contrib.downloadermiddleware.httpproxy.HttpProxyMiddleware': 750,
'scrapy.contrib.downloadermiddleware.chunked.ChunkedTransferMiddleware': 830,
'scrapy.contrib.downloadermiddleware.stats.DownloaderStats': 850,
'scrapy.contrib.downloadermiddleware.httpcache.HttpCacheMiddleware': 900,
} """
# from scrapy.contrib.downloadermiddleware.httpauth import HttpAuthMiddleware
# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
# DOWNLOADER_MIDDLEWARES = {
# 'step8_king.middlewares.DownMiddleware1': 100,
# 'step8_king.middlewares.DownMiddleware2': 500,
# } settings

  

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