简介
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
安装
Linux/mac
- pip3 install scrapy
Windows:
- 安装twsited
a. pip3 install wheel
b. 下载twisted http://www.lfd.uci.edu/~gohlke/pythonlibs/#twisted
c. 进入下载目录，执行 pip3 install Twisted-xxxxx.whl
- 安装scrapy
d. pip3 install scrapy -i http://pypi.douban.com/simple --trusted-host pypi.douban.com
- 安装pywin32
e. pip3 install pywin32 -i http://pypi.douban.com/simple --trusted-host pypi.douban.com
快速使用
Django：
django-admin startproject mysite
cd mysite
python manage.py startapp app01
# 写代码
python manage.py runserver
Scrapy：
创建project:
scrapy startproject xianglong # 创建项目
cd xianglong # 进入项目目录
scrapy genspider chouti chouti.com # 类似于django的创建app
# 写代码
scrapy crawl chouti --nolog # 启动
启动时，如果打印结果出现编码错误，在windows下可以在chouti.py中加上下面的内容
# -*- coding: utf-8 -*- import scrapy # import sys, io # sys.stdout=io.TextIOWrapper(sys.stdout.buffer,encoding='gb18030')
创建完成后的项目目录
文件说明：
- scrapy.cfg 项目的配置信息，主要为Scrapy命令行工具提供一个基础的配置信息。（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
在chouti.py中我们就可以编写我们的爬虫内容了
# -*- coding: utf-8 -*-
import scrapy
from bs4 import BeautifulSoup
from scrapy.selector import HtmlXPathSelector
from scrapy.http import Request
from ..items import XianglongItem
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']
# 起始URL，也就是爬取的url，可以有多个
start_urls = ['http://dig.chouti.com/', ]
# 爬取完成后默认执行的回调函数
def parse(self, response):
"""
当起始URL下载完毕后，自动执行parse函数：response封装了响应相关的所有内容。
:param response:
:return:
"""
hxs = HtmlXPathSelector(response=response)
# 去下载的页面中：找新闻
items = hxs.xpath("//div[@id='content-list']/div[@class='item']") # //获取子子孙孙 /获取子标签
for item in items:
href = item.xpath('.//div[@class="part1"]//a[1]/@href').extract_first() # .//获取相对当前对象的子子孙孙 /@href获取href属性
text = item.xpath('.//div[@class="part1"]//a[1]/text()').extract_first() # /text()获取文本内容
item = XianglongItem(title=text, href=href)
yield item
执行scrapy crawl chouti --nolog命令，会自动爬取start_urls中的网址，爬取完成后会执行回调函数parse，这里传的response就是爬取结果的对象，在处理这个对象时，我们不再使用bs4模块，而是使用scrapy提供好的HtmlXPathSelector，这个对象的用法很多
View Code
#!/usr/bin/env python
# -*- coding:utf-8 -*-
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)
在获取到想要的内容后，如果要做持久化，可以通过yield一个特殊的对象，这个对象就是下面这个文件中类的对象
该文件内容为
# -*- coding: utf-8 -*-
# Define here the models for your scraped items
#
# See documentation in:
# https://doc.scrapy.org/en/latest/topics/items.html
import scrapy
class XianglongItem(scrapy.Item):
# define the fields for your item here like:
# name = scrapy.Field()
title = scrapy.Field()
href = scrapy.Field()
只要yield这个特殊对象，这个框架会自动将这个对象传给下面的文件
在这个文件中我们可以执行持久化操作
# -*- coding: utf-8 -*-
# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://doc.scrapy.org/en/latest/topics/item-pipeline.html
class XianglongPipeline(object):
def process_item(self, item, spider): # 每次yield都会执行这个函数，spider为chouti.py中那个类的对象，item为我们yield的特殊对象
self.f.write(item['href']+'\n')
self.f.flush()
return item
def open_spider(self, spider):
"""
爬虫开始执行时，调用
:param spider:
:return:
"""
self.f = open('url.log','w')
def close_spider(self, spider):
"""
爬虫关闭时，被调用
:param spider:
:return:
"""
self.f.close()
要使用这个功能还需要在配置文件中配置，这段内容本来被注释了，只要取消注释就行了，300表示权重
ITEM_PIPELINES = {
'xianglong.pipelines.XianglongPipeline': 300,
}
如果我们在爬取完一个网页后，又从中得到了其它url，想要爬取这个url该怎么办呢，不能直接在start_urls中添加，这个start_urls只会在开始时读取一次，后面添加是不会管了，这时我们需要yield一个Request对象，这样框架就会帮我们爬取相关的内容了
# -*- coding: utf-8 -*-
import scrapy
from bs4 import BeautifulSoup
from scrapy.selector import HtmlXPathSelector
from scrapy.http import Request
from ..items import XianglongItem
class ChoutiSpider(scrapy.Spider):
name = 'chouti'
allowed_domains = ['chouti.com']
start_urls = ['http://dig.chouti.com/', ]
def parse(self, response):
"""
当起始URL下载完毕后，自动执行parse函数：response封装了响应相关的所有内容。
:param response:
:return:
"""
hxs = HtmlXPathSelector(response=response)
# 去下载的页面中：找新闻
items = hxs.xpath("//div[@id='content-list']/div[@class='item']")
for item in items:
href = item.xpath('.//div[@class="part1"]//a[1]/@href').extract_first()
text = item.xpath('.//div[@class="part1"]//a[1]/text()').extract_first()
item = XianglongItem(title=text, href=href)
yield item
pages = hxs.xpath('//div[@id="page-area"]//a[@class="ct_pagepa"]/@href').extract()
for page_url in pages:
page_url = "https://dig.chouti.com" + page_url
yield Request(url=page_url, callback=self.parse)
上面我们从爬取的内容中提取了一些a标签的href，然后yield了Request对象Request(url=page_url, callback=self.parse)，这样就可以爬取这个对象中的url了，爬取完成后还会执行我们传入的回调函数
相关配置，settings中
DEPTH_LIMIT = 2
这个表示只会爬取2层url，也就是第一层爬取过程中yield出的url为第二层，爬取第二层时yield出来的为第三层，第三层不会接着爬取
start_requests
如果我们在爬取start_urls中的地址后不想要执行默认的parse回调函数，而是想执行其它的函数，那么我们可以使用start_requests
# -*- coding: utf-8 -*-
import scrapy
from bs4 import BeautifulSoup
from scrapy.selector import HtmlXPathSelector
from scrapy.http import Request
from ..items import XianglongItem
from scrapy.http import HtmlResponse
from scrapy.http.response.html import HtmlResponse
"""
obj = ChoutiSpider()
obj.start_requests()
"""
class ChoutiSpider(scrapy.Spider):
name = 'chouti'
allowed_domains = ['chouti.com']
start_urls = ['https://dig.chouti.com/',]
def start_requests(self):
for url in self.start_urls:
yield Request(
url=url,
callback=self.parse,
headers={'User-Agent':'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36'}
)
def parse(self, response):
"""
当起始URL下载完毕后，自动执行parse函数：response封装了响应相关的所有内容。
:param response:
:return:
"""
pages = response.xpath('//div[@id="page-area"]//a[@class="ct_pagepa"]/@href').extract()
for page_url in pages:
page_url = "https://dig.chouti.com" + page_url
yield Request(url=page_url,callback=self.parse,headers={'User-Agent':'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36'})
爬取start_urls时其实会先执行start_requests，在里面会返回Request对象，我们只要修改Request对象的参数就可以改变回调函数
解析器
上面我们提到了使用HtmlXPathSelector来解析爬取的内容，其实response对象本身也有xpath方法，可以来解析数据
将字符串转换成对象：
- 方式一：
response.xpath('//div[@id='content-list']/div[@class='item']')
- 方式二：
hxs = HtmlXPathSelector(response=response)
items = hxs.xpath("//div[@id='content-list']/div[@class='item']")
查找规则：
//a
//div/a
//a[re:test(@id, "i\d+")]
items = hxs.xpath("//div[@id='content-list']/div[@class='item']")
for item in items:
item.xpath('.//div')
解析：
标签对象：xpath('/html/body/ul/li/a/@href')
列表： xpath('/html/body/ul/li/a/@href').extract()
值： xpath('//body/ul/li/a/@href').extract_first()
同时这个解析器还可以单独应用
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')
obj = response.xpath('//a[@id="i1"]/text()').extract_first()
print(obj)
pipelines
上面我们介绍了pipelines是用来持久化数据的，我们只是配置了一个类，其实从配置文件可以看出，由于有权重，所以可以配置多个pipelines，他们会按照权重从小到大执行
配置文件
ITEM_PIPELINES = {
'xianglong.pipelines.FilePipeline': 300,
'xianglong.pipelines.DBPipeline': 301,
}
pipelines
# -*- coding: utf-8 -*-
# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://doc.scrapy.org/en/latest/topics/item-pipeline.html
"""
当根据配置文件：
ITEM_PIPELINES = {
'xianglong.pipelines.FilePipeline': 300,
'xianglong.pipelines.DBPipeline': 301,
}
"""
from scrapy.exceptions import DropItem
class FilePipeline(object):
def process_item(self, item, spider):
print('写入文件',item.href)
return item
def open_spider(self, spider):
"""
爬虫开始执行时，调用
:param spider:
:return:
"""
print('打开文件')
def close_spider(self, spider):
"""
爬虫关闭时，被调用
:param spider:
:return:
"""
print('关闭文件')
class DBPipeline(object):
def process_item(self, item, spider):
print('数据库',item.href)
return item
def open_spider(self, spider):
"""
爬虫开始执行时，调用
:param spider:
:return:
"""
print('打开数据')
def close_spider(self, spider):
"""
爬虫关闭时，被调用
:param spider:
:return:
"""
print('关闭数据库')
可以看到FilePipeline的300比DBPipeline的301小，所以会先执行FilePipeline，执行结果
执行完FilePipeline的process_item就会接着执行DBPipeline的，我们可以看到这里FilePipeline的process_item的返回值为item，这个返回值就是下一个pipelines类接收到的item，也就是DBPipeline的process_item接收到的item，如果返回的是None，那么DBPipeline的process_item接收到的就是None，前一个类还可以抛出一个异常DropItem()，这样后面接收到这个异常的process_item就不会执行了
from scrapy.exceptions import DropItem
class FilePipeline(object):
def process_item(self, item, spider):
print('文件',item.href)
raise DropItem()
pipelines的所有方法
上面我们使用了pipelines的三种方法，其实pipelines总共有5种方法
# -*- coding: utf-8 -*-
# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://doc.scrapy.org/en/latest/topics/item-pipeline.html
"""
当根据配置文件：
ITEM_PIPELINES = {
'xianglong.pipelines.FilePipeline': 300,
'xianglong.pipelines.DBPipeline': 301,
}
找到相关的类：FilePipeline之后，会优先判断类中是否含有 from_crawler
如果有：
obj = FilePipeline.from_crawler()
没有则：
obj = FilePipeline()
obj.open_spider(..)
ob.process_item(..)
obj.close_spider(..)
"""
from scrapy.exceptions import DropItem
class FilePipeline(object):
def __init__(self,path):
self.path = path
self.f = None
@classmethod
def from_crawler(cls, crawler):
"""
初始化时候，用于创建pipeline对象
:param crawler:
:return:
"""
# return cls()
path = crawler.settings.get('XL_FILE_PATH')
return cls(path)
def process_item(self, item, spider):
self.f.write(item['href']+'\n')
return item
def open_spider(self, spider):
"""
爬虫开始执行时，调用
:param spider:
:return:
"""
self.f = open(self.path,'w')
def close_spider(self, spider):
"""
爬虫关闭时，被调用
:param spider:
:return:
"""
self.f.close()
from_crawler方法就是用来返回当前类的对象的，一般没有特别的操作可以不写他，如果想要从配置文件中读取东西（如写入文件的路径），就可以用到这个方法的crawler参数（配置必须是大写的），然后将获取的内容在实例化时传给类，再配合另一个初始化方法
就可以在当前对象中调用我们获取到的内容了，如上面的self.path就是从配置文件中获取的文件路径
POST/请求头/Cookie
之前我们都是发送的get请求，如何发送post请求并且携带请求头和cookie呢，其实都是在Request对象中设置
获取cookie我们可以手动获取，这里以登录抽屉并点赞为例
# -*- coding: utf-8 -*-
import scrapy
from bs4 import BeautifulSoup
from scrapy.selector import HtmlXPathSelector
from scrapy.http import Request
from ..items import XianglongItem
from scrapy.http import HtmlResponse
from scrapy.http.response.html import HtmlResponse
"""
obj = ChoutiSpider()
obj.start_requests()
"""
class ChoutiSpider(scrapy.Spider):
name = 'chouti'
allowed_domains = ['chouti.com']
start_urls = ['http://dig.chouti.com/',]
cookie_dict = {}
def start_requests(self):
for url in self.start_urls:
yield Request(url=url,callback=self.parse_index)
def parse_index(self,response):
# 原始cookie
# print(response.headers.getlist('Set-Cookie'))
# 解析后的cookie
from scrapy.http.cookies import CookieJar
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=8613121758648&password=woshiniba&oneMonth=1',
cookies=self.cookie_dict,
callback=self.parse_check_login
)
yield req
def parse_check_login(self,response):
print(response.text)
yield Request(
url='https://dig.chouti.com/link/vote?linksId=19440976',
method='POST',
cookies=self.cookie_dict,
callback=self.parse_show_result
)
def parse_show_result(self,response):
print(response.text)
上面我们通过CookieJar自己通过循环获取了cookie字典，并且在每次yield的Request对象中加上了cookies和请求头等信息，post请求还带上了body，请求体的信息，上面发送的是form-data格式的请求体，如果是json格式序列化一下即可
这样通过手动的方式获取cookie较为麻烦，我们可以让scrapy自动帮我们带cookie
View Code
# -*- coding: utf-8 -*-
import scrapy
from bs4 import BeautifulSoup
from scrapy.selector import HtmlXPathSelector
from scrapy.http import Request
from ..items import XianglongItem
from scrapy.http import HtmlResponse
from scrapy.http.response.html import HtmlResponse
"""
obj = ChoutiSpider()
obj.start_requests()
"""
class ChoutiSpider(scrapy.Spider):
name = 'chouti'
allowed_domains = ['chouti.com']
start_urls = ['http://dig.chouti.com/',]
def start_requests(self):
for url in self.start_urls:
yield Request(url=url,callback=self.parse_index,meta={'cookiejar':True})
def parse_index(self,response):
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.parse_check_login,
meta={'cookiejar': True}
)
yield req
def parse_check_login(self,response):
# print(response.text)
yield Request(
url='https://dig.chouti.com/link/vote?linksId=19440976',
method='POST',
callback=self.parse_show_result,
meta={'cookiejar': True}
)
def parse_show_result(self,response):
print(response.text)
只要在每一个Request对象中传入meta={'cookiejar': True}，那么scrapy就会自动帮我们获取cookie并在访问时携带了
配置文件制定是否允许操作cookie:
# Disable cookies (enabled by default) # COOKIES_ENABLED = False
去重规则
当我们爬取网站时，对于一些爬取过的url我们需要做记录，下次再遇到时就不再爬取了
在Request类实例化时有一个dont_filter=False参数，False表示需要去重，如果为True则不会执行去重
在去重时我们首先要定义配置文件
DUPEFILTER_CLASS = 'xianglong.dupe.MyDupeFilter'
定义完成后访问爬取url时会先执行这个类中的内容
from scrapy.dupefilter import BaseDupeFilter
from scrapy.utils.request import request_fingerprint
"""
1. 根据配置文件找到 DUPEFILTER_CLASS = 'xianglong.dupe.MyDupeFilter'
2. 判断是否存在from_settings
如果有：
obj = MyDupeFilter.from_settings()
否则：
obj = MyDupeFilter()
"""
class MyDupeFilter(BaseDupeFilter):
def __init__(self):
self.record = set()
@classmethod
def from_settings(cls, settings):
return cls()
def request_seen(self, request):
ident = request_fingerprint(request)
if ident in self.record:
print('已经访问过了', request.url)
return True
self.record.add(ident)
def open(self): # can return deferred 可以打开redis
pass
def close(self, reason): # can return a deferred 可以关闭redis
pass
在这个类中我们定义了一个空集合，每次拿到要爬取的url后会先判断这个url在不在集合中，如果在，那么说明已经访问过了，return True，如果不在则添加到集合再访问，这里添加url时我们不是直接添加的url，而是利用request_fingerprint(request)对这个类进行加密
这样可以固定存入的长度，而且如果是存入url，有些url只是参数的位置变了，其实还是一样的，但是只存url则无法判断
为请求创建唯一标识
http://www.oldboyedu.com?id=1&age=2 http://www.oldboyedu.com?age=2&id=1 from scrapy.utils.request import request_fingerprint from scrapy.http import Request u1 = Request(url='http://www.oldboyedu.com?id=1&age=2') u2 = Request(url='http://www.oldboyedu.com?age=2&id=1') result1 = request_fingerprint(u1) result2 = request_fingerprint(u2) print(result1,result2) # c49a0582ee359d61d0fe5f28084b2ea04106050d c49a0582ee359d61d0fe5f28084b2ea04106050d
可以看到通过request_fingerprint处理后存入的值长度固定，且只是参数位置不同的url存入的值也相同
记录到低要不要放在数据库
访问记录可以放在redis中【使用redis集合存储】
dont_filter到低在哪里
from scrapy.core.scheduler import Scheduler
def enqueue_request(self, request):
# request.dont_filter=False
# self.df.request_seen(request):
# - True,已经访问
# - False，未访问
# request.dont_filter=True，全部加入到调度器
if not request.dont_filter and self.df.request_seen(request):
self.df.log(request, self.spider)
return False
# 如果往下走，把请求加入调度器
dqok = self._dqpush(request)
下载中间件
对爬虫中所有请求发送时，携带请求头
方案一：在每个Request对象中添加一个请求头
方案二：使用下载中间件
配置文件
DOWNLOADER_MIDDLEWARES = {
'xianglong.middlewares.UserAgentDownloaderMiddleware': 543,
}
# -*- coding: utf-8 -*-
# Define here the models for your spider middleware
#
# See documentation in:
# https://doc.scrapy.org/en/latest/topics/spider-middleware.html
from scrapy import signals
class UserAgentDownloaderMiddleware(object):
@classmethod
def from_crawler(cls, crawler):
# This method is used by Scrapy to create your spiders.
s = cls()
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
request.headers['User-Agent'] = "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36"
# return None # 继续执行后续的中间件的process_request
# from scrapy.http import Request
# return Request(url='www.baidu.com') # 重新放入调度器中，当前请求不再继续处理
# from scrapy.http import HtmlResponse # 执行从最后一个开始执行所有的process_response
# return HtmlResponse(url='www.baidu.com',body=b'asdfuowjelrjaspdoifualskdjf;lajsdf')
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
中间件中不同的return值有不同的结果，在process_request中如果return的是一个request对象，则会返回调度器，访问这个request，这样会成为一个死循环，如果return None，则继续执行，如果返回一个Response对象，则从最后一个开始执行所有process_response
如果抛出异常则执行process_exception，在process_response中如果return的是一个request对象则返回调度器访问这个request，如果返回Response对象则继续执行，如果抛出异常则执行process_exception
方案三：内置下载中间件
配置文件：
USER_AGENT = 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36'
scrapy中如何添加代理
方式一：内置添加代理功能
# -*- coding: utf-8 -*-
import os
import scrapy
from scrapy.http import Request
class ChoutiSpider(scrapy.Spider):
name = 'chouti'
allowed_domains = ['chouti.com']
start_urls = ['https://dig.chouti.com/']
def start_requests(self):
os.environ['HTTP_PROXY'] = "http://192.168.11.11"
for url in self.start_urls:
yield Request(url=url,callback=self.parse)
def parse(self, response):
print(response)
只需要添加os.environ['HTTP_PROXY'] = "http://192.168.11.11"，就可以添加代理了，HTTP可以更改成其它名字 但是这种方法会一直使用代理ip进行爬取，容易被封 方式二：自定义下载中间件 配置下载中间件
import random
import base64
import six
def to_bytes(text, encoding=None, errors='strict'):
"""Return the binary representation of `text`. If `text`
is already a bytes object, return it as-is."""
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 MyProxyDownloaderMiddleware(object):
def process_request(self, request, spider):
proxy_list = [
{'ip_port': '111.11.228.75:80', 'user_pass': 'xxx:123'},
{'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(proxy_list)
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)
else:
request.meta['proxy'] = to_bytes("http://%s" % proxy['ip_port'])
这种方法每次访问会随机从代理ip中选一个使用
配置文件
DOWNLOADER_MIDDLEWARES = {
# 'xiaohan.middlewares.MyProxyDownloaderMiddleware': 543,
}
scrapy中如何处理https
如果是花钱买的认证那么我们不需要进行操作就可以直接访问，如果是自己生成的https证书，那么要进行下面的操作
middleware中间件文件中
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))
)
配置文件中
DOWNLOADER_HTTPCLIENTFACTORY = "scrapy.core.downloader.webclient.ScrapyHTTPClientFactory" DOWNLOADER_CLIENTCONTEXTFACTORY = "xiaohan.middlewares.MySSLFactory"
下载中间件的作用？
在每次下载前和下载后对请求和响应可以定制功能。例如：user-agent/代理/cookie
爬虫中间件
编写
middlewares.py
class XiaohanSpiderMiddleware(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.
def __init__(self):
pass
@classmethod
def from_crawler(cls, crawler):
# This method is used by Scrapy to create your spiders.
s = cls()
return s
# 每次下载完成之后，未执行parse函数之前。
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.
print('process_spider_input',response)
return None
# 执行完回调函数执行
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.
print('process_spider_output',response)
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
# 爬虫启动时，第一次执行start_requests时，触发。（只执行一次）
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).
print('process_start_requests')
for r in start_requests:
yield r
应用
SPIDER_MIDDLEWARES = {
'xiaohan.middlewares.XiaohanSpiderMiddleware': 543,
}
信号
首先创建一个新的文件
extends.py
from scrapy import signals
class MyExtension(object):
def __init__(self):
pass
@classmethod
def from_crawler(cls, crawler):
obj = cls()
# 在爬虫打开时，触发spider_opened信号相关的所有函数：xxxxxxxxxxx
crawler.signals.connect(obj.xxxxxxxxxxx1, signal=signals.spider_opened)
# 在爬虫关闭时，触发spider_closed信号相关的所有函数：xxxxxxxxxxx
crawler.signals.connect(obj.uuuuuuuuuu, signal=signals.spider_closed)
return obj
def xxxxxxxxxxx1(self, spider):
print('open')
def uuuuuuuuuu(self, spider):
print('close')
return obj
在这里定义一个类，这个类实例化时，可以添加触发信号时的函数
配置文件
EXTENSIONS = {
'xiaohan.extends.MyExtension':500,
}
这条配置其实就是会实例化这个类的对象，也就是调用上面的from_crawler方法，而这个方法中又绑定了信号函数
配置文件
Settings
# -*- 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
自定义命令
首先创建一个commands目录，在其中创建一个文件，文件名就是命令名
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()
这样使用scrapy crawlall命令启动项目就可以执行所有的spider爬虫文件了，这里的self.crawler_process.crawl(name, **opts.__dict__)和self.crawler_process.start()就是爬虫项目的入口
short_desc中的内容就是scrapy --help时能看到的命令解释
源码
def run(self, args, opts):
from scrapy.crawler import CrawlerProcess
CrawlerProcess.crawl
CrawlerProcess.start
"""
self.crawler_process对象中含有：_active = {d,}
"""
self.crawler_process.crawl('chouti',**opts.__dict__)
self.crawler_process.crawl('cnblogs',**opts.__dict__)
#
self.crawler_process.start()
TinyScrapy
示例1
from twisted.web.client import getPage
from twisted.internet import reactor
from twisted.internet import defer
url_list = ['http://www.bing.com', 'http://www.baidu.com', ]
def callback(arg):
print('回来一个', arg)
defer_list = []
for url in url_list:
ret = getPage(bytes(url, encoding='utf8'))
ret.addCallback(callback)
defer_list.append(ret)
def stop(arg):
print('已经全部现在完毕', arg)
reactor.stop()
d = defer.DeferredList(defer_list)
d.addBoth(stop)
reactor.run()
示例1
示例2
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from twisted.web.client import getPage
from twisted.internet import reactor
from twisted.internet import defer
@defer.inlineCallbacks
def task(url):
ret = getPage(bytes(url, encoding='utf8'))
ret.addCallback(callback)
yield ret
def callback(arg):
print('回来一个', arg)
url_list = ['http://www.bing.com', 'http://www.baidu.com', ]
defer_list = []
for url in url_list:
ret = task(url)
defer_list.append(ret)
def stop(arg):
print('已经全部现在完毕', arg)
reactor.stop()
d = defer.DeferredList(defer_list)
d.addBoth(stop)
reactor.run()
示例2
示例3
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from twisted.internet import defer
from twisted.web.client import getPage
from twisted.internet import reactor
import threading
def _next_request():
_next_request_from_scheduler()
def _next_request_from_scheduler():
ret = getPage(bytes('http://www.chouti.com', encoding='utf8'))
ret.addCallback(callback)
ret.addCallback(lambda _: reactor.callLater(0, _next_request))
_closewait = None
@defer.inlineCallbacks
def engine_start():
global _closewait
_closewait = defer.Deferred()
yield _closewait
@defer.inlineCallbacks
def task(url):
reactor.callLater(0, _next_request)
yield engine_start()
counter = 0
def callback(arg):
global counter
counter +=1
if counter == 10:
_closewait.callback(None)
print('one', len(arg))
def stop(arg):
print('all done', arg)
reactor.stop()
if __name__ == '__main__':
url = 'http://www.cnblogs.com'
defer_list = []
deferObj = task(url)
defer_list.append(deferObj)
v = defer.DeferredList(defer_list)
v.addBoth(stop)
reactor.run()
示例3
模拟scrapy框架
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from twisted.web.client import getPage, defer
from twisted.internet import reactor
import queue
class Response(object):
def __init__(self, body, request):
self.body = body
self.request = request
self.url = request.url
@property
def text(self):
return self.body.decode('utf-8')
class Request(object):
def __init__(self, url, callback=None):
self.url = url
self.callback = callback
class Scheduler(object):
def __init__(self, engine):
self.q = queue.Queue()
self.engine = engine
def enqueue_request(self, request):
self.q.put(request)
def next_request(self):
try:
req = self.q.get(block=False)
except Exception as e:
req = None
return req
def size(self):
return self.q.qsize()
class ExecutionEngine(object):
def __init__(self):
self._closewait = None
self.running = True
self.start_requests = None
self.scheduler = Scheduler(self)
self.inprogress = set()
def check_empty(self, response):
if not self.running:
self._closewait.callback('......')
def _next_request(self):
while self.start_requests:
try:
request = next(self.start_requests)
except StopIteration:
self.start_requests = None
else:
self.scheduler.enqueue_request(request)
while len(self.inprogress) < 5 and self.scheduler.size() > 0: # 最大并发数为5
request = self.scheduler.next_request()
if not request:
break
self.inprogress.add(request)
d = getPage(bytes(request.url, encoding='utf-8'))
d.addBoth(self._handle_downloader_output, request)
d.addBoth(lambda x, req: self.inprogress.remove(req), request)
d.addBoth(lambda x: self._next_request())
if len(self.inprogress) == 0 and self.scheduler.size() == 0:
self._closewait.callback(None)
def _handle_downloader_output(self, body, request):
"""
获取内容，执行回调函数，并且把回调函数中的返回值获取，并添加到队列中
:param response:
:param request:
:return:
"""
import types
response = Response(body, request)
func = request.callback or self.spider.parse
gen = func(response)
if isinstance(gen, types.GeneratorType):
for req in gen:
self.scheduler.enqueue_request(req)
@defer.inlineCallbacks
def start(self):
self._closewait = defer.Deferred()
yield self._closewait
def open_spider(self, spider, start_requests):
self.start_requests = start_requests
self.spider = spider
reactor.callLater(0, self._next_request)
class Crawler(object):
def __init__(self, spidercls):
self.spidercls = spidercls
self.spider = None
self.engine = None
@defer.inlineCallbacks
def crawl(self):
self.engine = ExecutionEngine()
self.spider = self.spidercls()
start_requests = iter(self.spider.start_requests())
start_requests = iter(start_requests)
self.engine.open_spider(self.spider, start_requests)
yield self.engine.start()
class CrawlerProcess(object):
def __init__(self):
self._active = set()
self.crawlers = set()
def crawl(self, spidercls, *args, **kwargs):
crawler = Crawler(spidercls)
self.crawlers.add(crawler)
d = crawler.crawl(*args, **kwargs)
self._active.add(d)
return d
def start(self):
dl = defer.DeferredList(self._active)
dl.addBoth(self._stop_reactor)
reactor.run()
def _stop_reactor(self, _=None):
reactor.stop()
class Spider(object):
def start_requests(self):
for url in self.start_urls:
yield Request(url)
class ChoutiSpider(Spider):
name = "chouti"
start_urls = [
'http://dig.chouti.com/',
]
def parse(self, response):
print(response.text)
class CnblogsSpider(Spider):
name = "cnblogs"
start_urls = [
'http://www.cnblogs.com/',
]
def parse(self, response):
print(response.text)
if __name__ == '__main__':
spider_cls_list = [ChoutiSpider, CnblogsSpider]
crawler_process = CrawlerProcess()
for spider_cls in spider_cls_list:
crawler_process.crawl(spider_cls)
crawler_process.start()
模拟scrapy框架
参考版
#!/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.cnblogs.com/', '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()
参考版
