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, 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)。或者发送新的请求 - 项目管道(Pipeline)
在items被提取后负责处理它们,主要包括清理、验证、持久化(比如存到数据库)等操作 - 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。(最新版本,没有了)
概括scrapy框架分成几部分:
爬虫,引擎,pipeline,调度器,下载器
持久化:通俗的讲,就是瞬时数据持久化为持久数据。主要应用是将内存中的对象存储在数据库中,或者存储在磁盘文件中、XML数据文件中等等
Scrapy运行流程大概如下:
1.引擎从调度器中取出一个链接(URL)用于接下来的抓取
2.引擎把URL封装成一个请求(Request)传给下载器
3.下载器把资源下载下来,并封装成应答包(Response)
4.爬虫解析Response
5.解析出实体(Item),则交给管道进行进一步的处理
6.解析出的是 链接(URL),则把URL交给调度器等待抓取
一.基本使用
1.基本命令
1. 创建爬虫项目
scrapy startproject 项目名称
- scrapy startproject sp1
2.创建爬虫应用
cd sp1
scrapy genspider baidu baidu.com
PS:
查看所有命令:scrapy gensipider -l
查看模板命令:scrapy gensipider -d 模板名称
3. scrapy crawl 爬虫应用名称
- 运行单独爬虫应用
4. scrapy list
- 展示爬虫应用列表
2.项目结构以及爬虫应用简介
project_name/
scrapy.cfg
project_name/
__init__.py
items.py
pipelines.py
settings.py
spiders/
__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 scrapy
class 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
爬虫1.py
import sys,os
sys.stdout=io.TextIOWrapper(sys.stdout.buffer,encoding='gb18030')
关于Windows编码
3.小试牛刀
# -*- coding: utf-8 -*-
import scrapy
from scrapy.selector import HtmlXPathSelector
from scrapy.http.request import Request
class ChoutiSpider(scrapy.Spider):
# scrapy crawl chouti --nolog,启动爬虫命令
name = 'chouti'
#允许的域名
allowed_domains = ['chouti.com']
#起始URL
start_urls = ['http://chouti.com/']
has_request_set = {}
def parse(self, response):
print('response.url',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
对于上述代码重要之处:
- 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
4.Scrapy定制起始URL函数
#-------------标配
import scrapy
class BaiduSpider(scrapy.Spider):
name = 'baidu'
allowed_domains = ['baidu.com']
start_urls = ['http://baidu.com/']
def parse(self, response):
print(response.text)
#-------------自定制
import scrapy
from scrapy.http import Request
class ChoutiSpider(scrapy.Spider):
name = 'chouti'
allowed_domains = ['chouti.com']
start_urls = ['http://chouti.com/']
def start_requests(self): ##返回 可迭代对象或生成器
for url in self.start_urls:
yield Request(url, dont_filter=True, callback=self.parse1)
def parse1(self, response):
pass
View Code
5.POST请求,请求头,cookie
requests.get(params={}, headers={}, cookies={})
requests.post(params={}, headers={}, cookies={}, data={}, json={})
GET请求:
url,
method='GET',
headers={},
cookies={}, cookiejar
POST请求:
url,
method='GET',
headers={},
cookies={}, cookiejar
body=None,
#请求头格式一
application/x-www-form-urlencoded; charset=UTF-8
form_data = {
'user':'Tom',
'pwd': 123
}
import urllib.parse
data = urllib.parse.urlencode({'k1':'v1','k2':'v2'})
结果:"k1=v1&k2=v3"
#请求头格式二
application/json; charset=UTF-8
json.dumsp()
"{k1:'v1','k2':'v2'}"
示例:
Request(
url='http://dig.chouti.com/login',
method='POST',
headers={'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'},
body='phone=861517243291&password=pppppppp&oneMonth=1',
callback=self.check_login
)
Get,Post请求
class ChoutiSpider(scrapy.Spider):
name = 'chouti'
allowed_domains = ['chouti.com']
start_urls = ['http://chouti.com/']
cookie_dict = {}
"""
1. 发送一个GET请求,抽屉
获取cookie
2. 用户密码POST登录:携带上一次cookie
返回值:9999
3. 为所欲为,携带cookie
"""
def start_requests(self):
for url in self.start_urls:
yield Request(url, dont_filter=True,callback=self.parse1)
def parse1(self,response):
# response.text 首页所有内容
from scrapy.http.cookies import CookieJar
cookie_jar = CookieJar() # 对象,中封装了 cookies
cookie_jar.extract_cookies(response, response.request) # 去响应中获取cookies
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
post_dict = {
'phone': '8615131255089',
'password': 'woshiniba',
'oneMonth': 1,
}
import urllib.parse
# 目的:发送POST进行登录
yield Request(
url="http://dig.chouti.com/login",
method='POST',
cookies=self.cookie_dict,
body=urllib.parse.urlencode(post_dict),
headers={'Content-Type':'application/x-www-form-urlencoded; charset=UTF-8'},
callback=self.parse2
)
Cookie
5.选择器
5.格式化处理
上述实例只是简单的处理,所以在parse方法中直接处理。如果对于想要获取更多的数据处理,则可以利用Scrapy的items将数据格式化,然后统一交由pipelines来处理。
import scrapy
from scrapy.http import Request
from scrapy.selector import Selector
class JianDanSpider(scrapy.Spider):
name = 'jiandan'
allowed_domains = ['jandan.net']
start_urls = ['http://jandan.net/']
def start_requests(self):
for url in self.start_urls:
yield Request(url, dont_filter=True,callback=self.parse1)
def parse1(self,response):
# response.text 首页所有内容
hxs = Selector(response)
a_list = hxs.xpath('//div[@class="indexs"]/h2')
for tag in a_list:
url = tag.xpath('./a/@href').extract_first()
text = tag.xpath('./a/text()').extract_first()
from ..items import Sp2Item
yield Sp2Item(url=url,text=text)
# 获取页码 [url,url]
"""
for url in url_list:
yield Request(url=url,callback=self.parse1)
"""
spiders/jiandan.py
import scrapy
class Sp2Item(scrapy.Item):
# define the fields for your item here like:
# name = scrapy.Field()
url = scrapy.Field()
text = scrapy.Field()
items.py
class Sp2Pipeline(object):
def __init__(self):
self.f = None
def process_item(self, item, spider):
"""
:param item: 爬虫中yield回来的对象
:param spider: 爬虫对象 obj = JianDanSpider()
:return:
"""
if spider.name == 'jiadnan':
pass
print(item)
self.f.write('....')
# 将item传递给下一个pipeline的process_item方法
# return item
# from scrapy.exceptions import DropItem
# raise DropItem() 下一个pipeline的process_item方法不在执行
@classmethod
def from_crawler(cls, crawler):
"""
初始化时候,用于创建pipeline对象
:param crawler:
:return:
"""
# val = crawler.settings.get('MMMM') #settings 设置 数据库
print('执行pipeline的from_crawler,进行实例化对象')
return cls()
def open_spider(self,spider):
"""
爬虫开始执行时,调用
:param spider:
:return:
"""
print('打开爬虫')
self.f = open('a.log','a+')
def close_spider(self,spider):
"""
爬虫关闭时,被调用
:param spider:
:return:
"""
self.f.close()
#再加个一个
class Sp3Pipeline(object):
def __init__(self):
self.f = None
def process_item(self, item, spider):
"""
:param item: 爬虫中yield回来的对象
:param spider: 爬虫对象 obj = JianDanSpider()
:return:
"""
print(item)
self.f.write('....')
return item
@classmethod
def from_crawler(cls, crawler):
"""
初始化时候,用于创建pipeline对象
:param crawler:
:return:
"""
# val = crawler.settings.get('MMMM')
print('执行pipeline的from_crawler,进行实例化对象')
return cls()
def open_spider(self, spider):
"""
爬虫开始执行时,调用
:param spider:
:return:
"""
print('打开爬虫')
self.f = open('a.log', 'a+')
def close_spider(self, spider):
"""
爬虫关闭时,被调用
:param spider:
:return:
"""
self.f.close()
pipelines
ITEM_PIPELINES = {
'sp2.pipelines.Sp2Pipeline': 300,
'sp2.pipelines.Sp3Pipeline': 100,
}
# 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。(越小越优先)
settings.py
对于pipeline可以做更多,如下:
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('000000')
def close_spider(self,spider):
"""
爬虫关闭时,被调用
:param spider:
:return:
"""
print('111111')
"""
检测 CustomPipeline类中是否有 from_crawler方法
如果有:
obj = 类.from_crawler()
如果没有:
obj = 类()
obj.open_spider()
while True:
爬虫运行,并且执行parse各种各样的from_crawler方法,yield item
obj.process_item()
obj.close_spider()
"""
View Code
6.去重
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
自定义URL去重:
class RepeatUrl:
def __init__(self):
self.visited_url = set() # 放在当前服务的内存
@classmethod
def 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 True
self.visited_url.add(request.url)
return False
def 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)
rep.py
在settings.py配置:
DUPEFILTER_CLASS = 'sp1.rep.RepeatUrl'
7.基于信号自定义扩展
利用信号在指定位置注册制定操作
from scrapy import signals
class MyExtension(object):
def __init__(self, value):
self.value = value
@classmethod
def from_crawler(cls, crawler):
val = crawler.settings.getint('MMMM')
ext = cls(val)
# 在scrapy中注册信号: spider_opened
crawler.signals.connect(ext.opened, signal=signals.spider_opened)
# 在scrapy中注册信号: spider_closed
crawler.signals.connect(ext.closed, signal=signals.spider_closed)
return ext
def opened(self, spider):
print('基于信号:open')
def closed(self, spider):
print('基于信号:close')
#settings.py 配置
# EXTENSIONS = {
# 'sp1.extends.MyExtension': 100,
# }
View Code
#Django的信号:给我们预留的扩展功能。
就是一些动作发生的时候,信号允许特定的发送者去提醒一些接受者。
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
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
"""
#最重要的两种情况
"""
from scrapy.http import Request
# print(request)
# request.method = "POST"
request.headers['proxy'] = "{'ip_port': '111.11.228.75:80', 'user_pass': ''},"
return None
"""
"""
from scrapy.http import Response
import requests
v = request.get('http://www.baidu.com')
data = Response(url='xxxxxxxx',body=v.content,request=request)
return data
"""
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')
# from scrapy.http import Response
# response.encoding = 'utf-8'
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
下载中间件
9.自定制命令
- 在spiders同级创建任意目录,如:commands
- 在其中创建 crawlall.py 文件 (此处文件名就是自定义的命令)
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
- 在settings.py 中添加配置 COMMANDS_MODULE = '项目名称.目录名称'
- 在项目目录执行命令:scrapy crawlall
10.代理
本质就是设置请求头
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,
}
"""
View Code
#源码(了解)
从模块 进入源码:
from scrapy.downloadermiddlewares.httpproxy import HttpProxyMiddleware
源码:
def _set_proxy(self, request, scheme):
creds, proxy = self.proxies[scheme] #第一个 授权,第二个 代理
request.meta['proxy'] = proxy
if creds:
request.headers['Proxy-Authorization'] = b'Basic ' + creds
from urllib.request import getproxies
源码:
# Proxy handling
def getproxies_environment():
proxies = {}
for name, value in os.environ.items():
name = name.lower()
if value and name[-6:] == '_proxy':
proxies[name[:-6]] = value
if 'REQUEST_METHOD' in os.environ:
proxies.pop('http', None)
for name, value in os.environ.items():
if name[-6:] == '_proxy': #------》【-6】
name = name.lower()
if value:
proxies[name[:-6]] = value
else:
proxies.pop(name[:-6], None)
return proxies
View Code
11、其他
# -*- 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配置文件
12.TinyScrapy
#!/usr/bin/env python
# -*- coding:utf-8 -*-
import types
from twisted.internet import defer
from twisted.web.client import getPage
from twisted.internet import reactor
class Request(object):
def __init__(self, url, callback):
self.url = url
self.callback = callback
self.priority = 0
class HttpResponse(object):
def __init__(self, content, request):
self.content = content
self.request = request
class ChouTiSpider(object):
def start_requests(self):
url_list = ['', 'http://www.bing.com']
for url in url_list:
yield Request(url=url, callback=self.parse)
def parse(self, response):
print(response.request.url)
# yield Request(url="http://www.baidu.com", callback=self.parse)
from queue import Queue
Q = Queue()
class CallLaterOnce(object):
def __init__(self, func, *a, **kw):
self._func = func
self._a = a
self._kw = kw
self._call = None
def schedule(self, delay=0):
if self._call is None:
self._call = reactor.callLater(delay, self)
def cancel(self):
if self._call:
self._call.cancel()
def __call__(self):
self._call = None
return self._func(*self._a, **self._kw)
class Engine(object):
def __init__(self):
self.nextcall = None
self.crawlling = []
self.max = 5
self._closewait = None
def get_response(self,content, request):
response = HttpResponse(content, request)
gen = request.callback(response)
if isinstance(gen, types.GeneratorType):
for req in gen:
req.priority = request.priority + 1
Q.put(req)
def rm_crawlling(self,response,d):
self.crawlling.remove(d)
def _next_request(self,spider):
if Q.qsize() == 0 and len(self.crawlling) == 0:
self._closewait.callback(None)
if len(self.crawlling) >= 5:
return
while len(self.crawlling) < 5:
try:
req = Q.get(block=False)
except Exception as e:
req = None
if not req:
return
d = getPage(req.url.encode('utf-8'))
self.crawlling.append(d)
d.addCallback(self.get_response, req)
d.addCallback(self.rm_crawlling,d)
d.addCallback(lambda _: self.nextcall.schedule())
@defer.inlineCallbacks
def crawl(self):
spider = ChouTiSpider()
start_requests = iter(spider.start_requests())
flag = True
while flag:
try:
req = next(start_requests)
Q.put(req)
except StopIteration as e:
flag = False
self.nextcall = CallLaterOnce(self._next_request,spider)
self.nextcall.schedule()
self._closewait = defer.Deferred()
yield self._closewait
@defer.inlineCallbacks
def pp(self):
yield self.crawl()
_active = set()
obj = Engine()
d = obj.crawl()
_active.add(d)
li = defer.DeferredList(_active)
li.addBoth(lambda _,*a,**kw: reactor.stop())
reactor.run()
#额外拿出--注释
#!/usr/bin/env python
# -*- coding:utf-8 -*-
import types
from twisted.internet import defer
from twisted.web.client import getPage
from twisted.internet import reactor
from queue import Queue
class Request(object):
"""
封装请求相关信息
"""
def __init__(self, url, callback):
self.url = url
self.callback = callback
self.priority = 0
class HttpResponse(object):
"""
封装相应相关信息
"""
def __init__(self, content, request):
self.content = content
self.request = request
class Scheduler(object):
"""
任务调度器
"""
def __init__(self):
self.q = Queue()
def open(self):
pass
def next_request(self):
try:
request = self.q.get(block=False)
except Exception as e:
request = None
return request
def enqueue_request(self, request):
self.q.put(request,block=False)
def size(self):
return self.q.qsize()
class CallLaterOnce(object):
"""
用于封装:执行下次nextcall.schedule()时,可以携带spider参数
"""
def __init__(self, func, *a, **kw):
self._func = func
self._a = a
self._kw = kw
self._call = None
def schedule(self, delay=0):
if self._call is None:
self._call = reactor.callLater(delay, self)
def cancel(self):
if self._call:
self._call.cancel()
def __call__(self):
self._call = None
return self._func(*self._a, **self._kw)
class ExecutionEngine(object):
def __init__(self, crawler):
self.crawler = crawler
self.nextcall = None
self.crawlling = []
self.max = 5
self._closewait = None
self.scheduler = None
def get_response(self, content, request):
response = HttpResponse(content, request)
gen = request.callback(response)
if isinstance(gen, types.GeneratorType):
for req in gen:
req.priority = request.priority + 1
self.scheduler.enqueue_request(req)
def _next_request(self, spider):
if self.scheduler.size() == 0 and len(self.crawlling) == 0:
self._closewait.callback(None)
if len(self.crawlling) >= 5:
return
while len(self.crawlling) < 5:
req = self.scheduler.next_request()
if not req:
return
d = getPage(req.url.encode('utf-8'))
self.crawlling.append(d)
#执行回调函数且向调度器中添加yield返回的request对象
d.addCallback(self.get_response, req)
#去掉
d.addCallback(lambda _,d:self.crawlling.remove(d), d)
#再去调度器中获取一个人物,继续执行下载(递归执行_next_request:这里的递归是说,执行一次在执行一次)
d.addCallback(lambda _: self.nextcall.schedule())
@defer.inlineCallbacks
def open_spider(self, spider, start_requests):
self.scheduler = Scheduler()
flag = True
while flag:
try:
req = next(start_requests)
self.scheduler.enqueue_request(req)
except StopIteration as e:
flag = False
self.nextcall = CallLaterOnce(self._next_request, spider)
self.nextcall.schedule()
yield None
@defer.inlineCallbacks
def start(self):
self._closewait = defer.Deferred()
yield self._closewait
class Crawler(object):
def __init__(self, spider_cls_path, settings):
self.spider_cls_path = spider_cls_path
self.settings = settings
self.spider = None
self.engine = None
def _create_spider(self):
"""
创建爬虫对象
:return:
"""
module_path, cls_name = self.spider_cls_path.rsplit('.', maxsplit=1)
import importlib
m = importlib.import_module(module_path)
cls = getattr(m, cls_name)
return cls()
def _create_engine(self):
"""
创建引擎
:return:
"""
return ExecutionEngine(self)
@defer.inlineCallbacks
def crawl(self):
"""
:param args:
:param kwargs:
:return:
"""
self.spider = self._create_spider()
self.engine = self._create_engine()
start_requests = iter(self.spider.start_requests())
#去获取数据
yield self.engine.open_spider(self.spider, start_requests)
#hold住请求,不终止
yield self.engine.start()
# _closewait.callback(None) 直到有此操作,才全部结束
class CrawlerProcess(object):
def __init__(self, settings):
self.settings = settings
self._active = set()
self.crawlers = set()
def crawl(self, spider_cls_path):
"""
创建Crawler对象
:param spider_cls_path: 爬虫spider路径
:param args:
:param kwargs:
:return:
"""
crawler = Crawler(spider_cls_path, self.settings) #实例化对象
d = crawler.crawl() # defer.Deferred() ----返回defer对象
self._active.add(d) #d 加到 _active。若执行完,_active里只有一个值,一个 defer对象
def _done(result):
self.crawlers.discard(crawler)
self._active.discard(d)
return result
return d.addBoth(_done)
def start(self):
"""
所有爬虫开始工作
:return:
"""
dl = defer.DeferredList(self._active)
dl.addBoth(self._stop_reactor)
reactor.run()
def _stop_reactor(self, _=None):
"""
爬虫爬去数据完毕
:return:
"""
reactor.stop()
class Commond(object):
def __init__(self):
self.crawl_process = CrawlerProcess({})
def run(self):
# spider_path_list = [
# "spider.chouti.ChoutiSpider",
# "spider.cnblogs.CnblogsSpider",
# ]
# for spider_cls_path in spider_path_list:
# self.crawl_process.crawl(spider_cls_path)
self.crawl_process.crawl('spider.chouti.ChoutiSpider') #只是当做 字符串,并未 实例化
self.crawl_process.start()
if __name__ == '__main__':
cmd = Commond() #如果是主函数,实例化一个对象
cmd.run()
engine.py