Scrapy 学习笔记（-）

Scrapy

Scrapy 是一个为了爬取网站数据，提取结构性数据而编写的应用框架。其可以应用在数据挖掘，信息处理或存储历史数据等一系列的程序中。其最初是为了页面抓取 (更确切来说, 网络抓取 )所设计的，也可以应用在获取API所返回的数据(例如 Amazon Associates Web Services ) 或者通用的网络爬虫。Scrapy用途广泛，可以用于数据挖掘、监测和自动化测试。

Scrapy 使用了 Twisted异步网络库来处理网络通讯。整体架构大致如下

Scrapy主要包括了以下组件：

引擎(Scrapy)
用来处理整个系统的数据流处理, 触发事务(框架核心)
调度器(Scheduler)
用来接受引擎发过来的请求, 压入队列中, 并在引擎再次请求的时候返回. 可以想像成一个URL（抓取网页的网址或者说是链接）的优先队列, 由它来决定下一个要抓取的网址是什么, 同时去除重复的网址
下载器(Downloader)
用于下载网页内容, 并将网页内容返回给蜘蛛(Scrapy下载器是建立在twisted这个高效的异步模型上的)
爬虫(Spiders)
爬虫是主要干活的, 用于从特定的网页中提取自己需要的信息, 即所谓的实体(Item)。用户也可以从中提取出链接,让Scrapy继续抓取下一个页面
项目管道(Pipeline)
负责处理爬虫从网页中抽取的实体，主要的功能是持久化实体、验证实体的有效性、清除不需要的信息。当页面被爬虫解析后，将被发送到项目管道，并经过几个特定的次序处理数据。
下载器中间件(Downloader Middlewares)
位于Scrapy引擎和下载器之间的框架，主要是处理Scrapy引擎与下载器之间的请求及响应。
爬虫中间件(Spider Middlewares)
介于Scrapy引擎和爬虫之间的框架，主要工作是处理蜘蛛的响应输入和请求输出。
调度中间件(Scheduler Middewares)
介于Scrapy引擎和调度之间的中间件，从Scrapy引擎发送到调度的请求和响应。

Scrapy运行流程大概如下：

引擎从调度器中取出一个链接(URL)用于接下来的抓取
引擎把URL封装成一个请求(Request)传给下载器
下载器把资源下载下来，并封装成应答包(Response)
爬虫解析Response
解析出实体（Item）,则交给实体管道进行进一步的处理
解析出的是链接（URL）,则把URL交给调度器等待抓取

一、安装：

Linux：pip3 install scrapyWindows：1、直接安装：pip3 install scrapy2、可能报错（需要安装twisted）：2.1、下载twisted http://www.lfd.uci.edu/~gohlke/pythonlibs/#twisted2.2、进入下载目录，执行 pip3 install Twisted‑17.1.0‑cp35‑cp35m‑win_amd64.whl3、 安装pywin32：pip install pywin32

二、基本使用

2.1、基本命令

1. scrapy startproject 项目名称- 在当前目录中创建中创建一个项目文件（类似于Django）2. scrapy genspider [-t template] <name> <domain>- 创建爬虫应用如：scrapy gensipider -t basic oldboy oldboy.comscrapy gensipider -t xmlfeed autohome autohome.com.cnPS:查看所有命令：scrapy gensipider -l查看模板命令：scrapy gensipider -d 模板名称3. scrapy list- 展示爬虫应用列表4. scrapy crawl 爬虫应用名称- 运行单独爬虫应用

2.2、项目结构以及爬虫应用简介

project_name/scrapy.cfgproject_name/__init__.pyitems.pypipelines.pysettings.pyspiders/__init__.py爬虫1.py爬虫2.py爬虫3.py

文件说明：

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

注意：一般创建爬虫文件时，以网站域名命名

import scrapyclass XiaoHuarSpider(scrapy.spiders.Spider):name = "xiaohuar"                            # 爬虫名称 *****allowed_domains = ["xiaohuar.com"]  # 允许的域名start_urls = ["http://www.xiaohuar.com/hua/",   # 其实URL
    ]def parse(self, response):# 访问起始URL并获取结果后的回调函数

import scrapy
from scrapy.selector import HtmlXPathSelector
from scrapy.http.request import Requestclass 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URLstart_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' % pagekey = self.md5(page_url)if key in self.has_request_set:passelse:self.has_request_set[key] = page_urlobj = Request(url=page_url, method='GET', callback=self.parse)yield obj@staticmethoddef md5(val):import hashlibha = hashlib.md5()ha.update(bytes(val, encoding='utf-8'))key = ha.hexdigest()return key

demo

执行此爬虫文件，则在终端进入项目目录执行如下命令：

scrapy crawl dig --nolog  # --nolog：不显示日志

对于上述代码重要之处在于：

Request是一个封装用户请求的类，在回调函数中yield该对象表示继续访问
HtmlXpathSelector用于结构化HTML代码并提供选择器功能

yield scrapy.Request(url, callback=self.parse)

解析：

因为使用的yield，而不是return。parse函数将会被当做一个生成器使用。scrapy会逐一获取parse方法中生成的结果，并判断该结果是一个什么样的类型。如果是request则加入爬取队列，如果是item类型则使用pipeline处理，其他类型则返回错误信息。具体见源代码

2.3、url去重

scrapy下的request中init自带参数：

其中有个参数：dont_filter = False ， scrapy默认使用 scrapy.dupefilter.RFPDupeFilter 进行去重，具体可进源码（RFPDupeFilter ）查看，相关配置：

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

我们自己自定义去重操作，这样能更灵活的操作数据，比如将已访问的url 存进内存、数据库、文件、缓存等，更换方式灵活

1）首先，我们要自定义url去重的类：RepeatFilter ，在setting.py中将scrapy默认去重的路径改成我们自定义的路径：

# setting.py
DUPEFILTER_CLASS = 'scrapy.dupefilter.RepeatFilter'

2）然后再新建dupefilter.py文件，在该py文件中自定义RepeatFilter类，重写RFPDupeFilter 类的几个方法：

def from_settings(cls, settings) : 会定义成类方法，默认调用的第一个方法就是这个方法，作用：实例化RepeatFilter
def request_seen(self, request) : 检查当前请求是否被访问过，返回True表示访问过，返回False表示未访问过
def open(self) : 开始爬取请求时调用
def close(self, reason) : 结束爬虫爬取时调用
def log(self, request, spider) : 日志记录

调用顺序：1、from_settings 方法 → 2、init 方法 → 3、open 方法 → 4、request_seen 方法 →5、close 方法

# dupefilter.py/RepeatFilter
class RepeatFilter(object):def __init__(self):self.visited_url = set()@classmethoddef from_settings(cls, settings):"""初始化时，调用:param settings: :return: """return cls()def request_seen(self, request):"""检测当前请求是否已经被访问过:param request: :return: True表示已经访问过；False表示未访问过"""if request.url in self.visited_url:return Trueself.visited_url.add(request.url)return Falsedef open(self):"""开始爬去请求时，调用:return: """print('open replication')def close(self, reason):"""结束爬虫爬取时，调用:param reason: :return: """print('close replication')def log(self, request, spider):"""记录日志:param request: :param spider: :return: """print('repeat', request.url)

2.4、pipelines相关

scrapy中items将数据格式化，之后传递给pipelines处理，

通过下述yield方法，即可将items数据传递到pipelines中，执行pipelines中各类下的 process_item 方法，进行数据持久化处理，执行优先级由setting中注册(ITEM_PIPELINES)配置的数据决定，数值越小越先执行

yield item_example  #此语句一执行，就会跳到pipelines.py下的类中执行其中的方法，比如 process_item方法：数据做持久化时调用 ，open_spider方法：爬虫开始爬取数据时调用的

pipelines相关类是在pipelines.py中编写的，要使pipelines.py下的类能正常运行，需要在setting中将需要用到的类注册进去，如：

#pipelines.py/ArticleImagePipeline类class ArticleImagePipeline(ImagesPipeline):def item_completed(self, results, item, info):if "front_image_url" in item:for ok, value in results:image_file_path = value["path"]item["front_image_path"] = image_file_pathreturn item  #return item：会将item交个下个类继续处理，如不想让其他类处理，则需手动报异常：Raise DropItem（），表示丢弃item，不再被其他类处理

setting中注册：

ITEM_PIPELINES = {'ArticleSpider.pipelines.ArticleImagePipeline': 2, # 自定义ArticleImagePipeline ，需配置好管道路径
}

pipelines中的类，也有几个方法，有点类似上述去重的类：

def process_item(self, item, spider) ：操作并进行持久化时调用
def from_crawler(cls, crawler) ：初始化时调用，用于读取setting信息及实例化pipelines对象
def open_spider(self,spider) ：爬虫开始执行时调用
def close_spider(self,spider) ：爬虫结束时调用

2.5、cookie相关

# -*- coding: utf-8 -*-
import scrapy
from scrapy.http.response.html import HtmlResponse
from scrapy.http import Request
from scrapy.http.cookies import CookieJarclass ChoutiSpider(scrapy.Spider):name = "chouti"allowed_domains = ["chouti.com"]start_urls = ('http://www.chouti.com/',)def start_requests(self):url = 'http://dig.chouti.com/'yield Request(url=url, callback=self.login, meta={'cookiejar': True})def login(self, response):print(response.headers.getlist('Set-Cookie'))req = Request(url='http://dig.chouti.com/login',method='POST',headers={'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'},body='phone=8613121758648&password=woshiniba&oneMonth=1',callback=self.check_login,meta={'cookiejar': True})yield reqdef check_login(self, response):print(response.text)

处理cookie

# -*- coding: utf-8 -*-
import scrapy
import sys
import io
from scrapy.http import Request
from scrapy.selector import Selector, HtmlXPathSelector
from ..items import ChoutiItemsys.stdout = io.TextIOWrapper(sys.stdout.buffer,encoding='gb18030')
from scrapy.http.cookies import CookieJar
class ChoutiSpider(scrapy.Spider):name = "chouti"allowed_domains = ["chouti.com",]start_urls = ['http://dig.chouti.com/']cookie_dict = Nonedef parse(self, response):cookie_obj = CookieJar()cookie_obj.extract_cookies(response,response.request)self.cookie_dict = cookie_obj._cookies  # cookie# 带上用户名密码+cookieyield Request(url="http://dig.chouti.com/login",method='POST',body = "phone=8615131255089&password=woshiniba&oneMonth=1",headers={'Content-Type': "application/x-www-form-urlencoded; charset=UTF-8"},cookies=cookie_obj._cookies,callback=self.check_login)def check_login(self,response):print(response.text)yield Request(url="http://dig.chouti.com/",callback=self.good)def good(self,response):id_list = Selector(response=response).xpath('//div[@share-linkid]/@share-linkid').extract()for nid in id_list:print(nid)url = "http://dig.chouti.com/link/vote?linksId=%s" % nidyield Request(url=url,method="POST",cookies=self.cookie_dict,callback=self.show)# page_urls = Selector(response=response).xpath('//div[@id="dig_lcpage"]//a/@href').extract()# for page in page_urls:#     url = "http://dig.chouti.com%s" % page#     yield Request(url=url,callback=self.good)def show(self,response):print(response.text)

示例：自动登录抽屉并批量点赞

2.6、Scrapy框架扩展，自定义扩展利用信号在指定位置注册制定操作

Scrapy框架扩展，scrapy提供一些扩展（钩子）可以供自定义操作，setting.py中：

EXTENSIONS = {'scrapy.extensions.telnet.TelnetConsole': None,
}

我们进入TelnetConsole 源码中，通过重写init方法、from_crawler方法，可以自定义我们的钩子

scrapy.signals中提供多种信号状态，可供我们自定义扩展钩子时使用：

engine_started = object()  # 引擎开始时
engine_stopped = object()  # 引擎结束时
spider_opened = object()  # 爬虫开始时
spider_idle = object()    #
spider_closed = object()   # 爬虫结束时
spider_error = object()   # 爬虫错误时
request_scheduled = object()   # request给到调度器时
request_dropped = object()  # request丢弃时
response_received = object()  # response接收时
response_downloaded = object()   # response下载时
item_scraped = object()  # item执行时
item_dropped = object()  # item丢弃时

自定义钩子：

新建 extensions.py文件，创建类 MyExtension

from scrapy import signalsclass MyExtension(object):def __init__(self, value):self.value = value@classmethoddef from_crawler(cls, crawler):val = crawler.settings.getint('MMMM')ext = cls(val)crawler.signals.connect(ext.spider_opened, signal=signals.spider_opened)crawler.signals.connect(ext.spider_closed, signal=signals.spider_closed)return extdef spider_opened(self, spider):print('open')def spider_closed(self, spider):print('close')

setting.py中注册：

EXTENSIONS = {# 'scrapy.extensions.telnet.TelnetConsole': None,'articlespider.extensions.MyExtend': 300,
}

2.7、setting.py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_DELAY2. 获取最大延迟 AUTOTHROTTLE_MAX_DELAY3. 设置初始下载延迟 AUTOTHROTTLE_START_DELAY4. 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_CONCURRENCYtarget_delay = latency / self.target_concurrencynew_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 HttpCacheMiddlewarefrom scrapy.extensions.httpcache import DummyPolicyfrom 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 textif 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.pyfrom scrapy.core.downloader.contextfactory import ScrapyClientContextFactoryfrom twisted.internet.ssl import (optionsForClientTLS, CertificateOptions, PrivateCertificate)class MySSLFactory(ScrapyClientContextFactory):def getCertificateOptions(self):from OpenSSL import cryptov1 = 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.HttpDownloadHandlerscrapy.core.downloader.webclient.ScrapyHTTPClientFactoryscrapy.core.downloader.contextfactory.ScrapyClientContextFactory相关配置DOWNLOADER_HTTPCLIENTFACTORYDOWNLOADER_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: '''passdef 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 resultdef 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 Nonedef 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_responseRequest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'''passdef 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_responseRequest 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 responsedef 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,
# }

setting.py

2.8、scrapy配置之自动限速以及缓存

"""
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_DELAY2. 获取最大延迟 AUTOTHROTTLE_MAX_DELAY3. 设置初始下载延迟 AUTOTHROTTLE_START_DELAY4. 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_CONCURRENCYtarget_delay = latency / self.target_concurrencynew_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

setting.py 动态限速

"""
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 HttpCacheMiddlewarefrom scrapy.extensions.httpcache import DummyPolicyfrom 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'

缓存

2.9、scrapy之默认代理及扩展代理

"""
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 textif 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,}"""

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2.10、scrapy之自定义https证书

"""
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.pyfrom scrapy.core.downloader.contextfactory import ScrapyClientContextFactoryfrom twisted.internet.ssl import (optionsForClientTLS, CertificateOptions, PrivateCertificate)class MySSLFactory(ScrapyClientContextFactory):def getCertificateOptions(self):from OpenSSL import cryptov1 = 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.HttpDownloadHandlerscrapy.core.downloader.webclient.ScrapyHTTPClientFactoryscrapy.core.downloader.contextfactory.ScrapyClientContextFactory相关配置DOWNLOADER_HTTPCLIENTFACTORYDOWNLOADER_CLIENTCONTEXTFACTORY"""

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2.11、 scrapy之爬虫中间件

1）下载中间件

"""
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_responseRequest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'''passdef 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_responseRequest 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 responsedef 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,}"""

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2）爬虫中间件

"""
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: '''passdef 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 resultdef 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 Nonedef 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,"""

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转载于:https://www.cnblogs.com/Eric15/articles/9733824.html