爬虫、框架scrapy

时间 2019-11-24

原文原文链接

阅读目录css

一介绍

Scrapy一个开源和协做的框架，其最初是为了页面抓取 (更确切来讲, 网络抓取 )所设计的，使用它能够以快速、简单、可扩展的方式从网站中提取所需的数据。但目前Scrapy的用途十分普遍，可用于如数据挖掘、监测和自动化测试等领域，也能够应用在获取API所返回的数据(例如 Amazon Associates Web Services ) 或者通用的网络爬虫。html

Scrapy 是基于twisted框架开发而来，twisted是一个流行的事件驱动的python网络框架。所以Scrapy使用了一种非阻塞（又名异步）的代码来实现并发。总体架构大体以下
python

The data flow in Scrapy is controlled by the execution engine, and goes like this:mysql

The Engine gets the initial Requests to crawl from the Spider.
The Engine schedules the Requests in the Scheduler and asks for the next Requests to crawl.
The Scheduler returns the next Requests to the Engine.
The Engine sends the Requests to the Downloader, passing through the Downloader Middlewares (see process_request()).
Once the page finishes downloading the Downloader generates a Response (with that page) and sends it to the Engine, passing through the Downloader Middlewares (see process_response()).
The Engine receives the Response from the Downloader and sends it to the Spider for processing, passing through the Spider Middleware (see process_spider_input()).
The Spider processes the Response and returns scraped items and new Requests (to follow) to the Engine, passing through the Spider Middleware (see process_spider_output()).
The Engine sends processed items to Item Pipelines, then send processed Requests to the Scheduler and asks for possible next Requests to crawl.
The process repeats (from step 1) until there are no more requests from the Scheduler.

Components：web

引擎(EGINE)

引擎负责控制系统全部组件之间的数据流，并在某些动做发生时触发事件。有关详细信息，请参见上面的数据流部分。ajax
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. 能够想像成一个URL的优先级队列, 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(DOWLOADER)
用于下载网页内容, 并将网页内容返回给EGINE，下载器是创建在twisted这个高效的异步模型上的
爬虫(SPIDERS)
SPIDERS是开发人员自定义的类，用来解析responses，而且提取items，或者发送新的请求
项目管道(ITEM PIPLINES)
在items被提取后负责处理它们，主要包括清理、验证、持久化（好比存到数据库）等操做
下载器中间件(Downloader Middlewares)
位于Scrapy引擎和下载器之间，主要用来处理从EGINE传到DOWLOADER的请求request，已经从DOWNLOADER传到EGINE的响应response，你可用该中间件作如下几件事
1. process a request just before it is sent to the Downloader (i.e. right before Scrapy sends the request to the website);
2. change received response before passing it to a spider;
3. send a new Request instead of passing received response to a spider;
4. pass response to a spider without fetching a web page;
5. silently drop some requests.
爬虫中间件(Spider Middlewares)
位于EGINE和SPIDERS之间，主要工做是处理SPIDERS的输入（即responses）和输出（即requests）

官网连接：https://docs.scrapy.org/en/latest/topics/architecture.html正则表达式

二安装

#Windows平台
    一、pip3 install wheel #安装后，便支持经过wheel文件安装软件，wheel文件官网：https://www.lfd.uci.edu/~gohlke/pythonlibs
    3、pip3 install lxml
    4、pip3 install pyopenssl
    五、下载并安装pywin32：https://sourceforge.net/projects/pywin32/files/pywin32/
    六、下载twisted的wheel文件：http://www.lfd.uci.edu/~gohlke/pythonlibs/#twisted
    七、执行pip3 install 下载目录\Twisted-17.9.0-cp36-cp36m-win_amd64.whl
    8、pip3 install scrapy
  
#Linux平台
    一、pip3 install scrapy

三命令行工具

#1 查看帮助
    scrapy -h
    scrapy <command> -h

#2 有两种命令：其中Project-only必须切到项目文件夹下才能执行，而Global的命令则不须要
    Global commands:
        startproject #建立项目   scrapy startprojact 项目名
        genspider    #建立爬虫程序  scrapy genspider 爬虫名 url
        settings     #若是是在项目目录下，则获得的是该项目的配置
        runspider    #运行一个独立的python文件，没必要建立项目
        shell        #scrapy shell url地址  在交互式调试，如选择器规则正确与否
        fetch        #独立于程单纯地爬取一个页面，能够拿到请求头
        view         #下载完毕后直接弹出浏览器，以此能够分辨出哪些数据是ajax请求
        version      #scrapy version 查看scrapy的版本，scrapy version -v查看scrapy依赖库的版本
    Project-only commands:
        crawl        #运行爬虫，必须建立项目才行，确保配置文件中ROBOTSTXT_OBEY = False
        check        #检测项目中有无语法错误
        list         #列出项目中所包含的爬虫名
        edit         #编辑器，通常不用
        parse        #scrapy parse url地址 --callback 回调函数  #以此能够验证咱们的回调函数是否正确
        bench        #scrapy bentch压力测试

#3 官网连接
    https://docs.scrapy.org/en/latest/topics/commands.html

#一、执行全局命令：请确保不在某个项目的目录下，排除受该项目配置的影响
scrapy startproject MyProject

cd MyProject
scrapy genspider baidu www.baidu.com

scrapy settings --get XXX #若是切换到项目目录下，看到的则是该项目的配置

scrapy runspider baidu.py

scrapy shell https://www.baidu.com
    response
    response.status
    response.body
    view(response)
    
scrapy view https://www.taobao.com #若是页面显示内容不全，不全的内容则是ajax请求实现的，以此快速定位问题

scrapy fetch --nolog --headers https://www.taobao.com

scrapy version #scrapy的版本

scrapy version -v #依赖库的版本


#二、执行项目命令：切到项目目录下
scrapy crawl baidu
scrapy check
scrapy list
scrapy parse http://quotes.toscrape.com/ --callback parse
scrapy bench

四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：算法

scrapy.cfg 项目的主配置信息，用来部署scrapy时使用，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：通常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。强调:配置文件的选项必须大写不然视为无效，正确写法USER_AGENT='xxxx'
spiders 爬虫目录，如：建立文件，编写爬虫规则

注意：通常建立爬虫文件时，以网站域名命名sql

#在项目目录下新建：entrypoint.py
from scrapy.cmdline import execute
execute(['scrapy', 'crawl', 'xiaohua'])

默认只能在cmd中执行爬虫，若是想在pycharm中执行须要作

import sys,os
sys.stdout=io.TextIOWrapper(sys.stdout.buffer,encoding='gb18030')

关于windows编码

五 Spiders

一、介绍mongodb

#一、Spiders是由一系列类（定义了一个网址或一组网址将被爬取）组成，具体包括如何执行爬取任务而且如何从页面中提取结构化的数据。

#二、换句话说，Spiders是你为了一个特定的网址或一组网址自定义爬取和解析页面行为的地方

二、Spiders会循环作以下事情

#一、生成初始的Requests来爬取第一个URLS，而且标识一个回调函数
第一个请求定义在start_requests()方法内默认从start_urls列表中得到url地址来生成Request请求，默认的回调函数是parse方法。回调函数在下载完成返回response时自动触发

#二、在回调函数中，解析response而且返回值
返回值能够4种：
        包含解析数据的字典
        Item对象
        新的Request对象（新的Requests也须要指定一个回调函数）
        或者是可迭代对象（包含Items或Request）

#三、在回调函数中解析页面内容
一般使用Scrapy自带的Selectors，但很明显你也可使用Beutifulsoup，lxml或其余你爱用啥用啥。

#四、最后，针对返回的Items对象将会被持久化到数据库
经过Item Pipeline组件存到数据库：https://docs.scrapy.org/en/latest/topics/item-pipeline.html#topics-item-pipeline）
或者导出到不一样的文件（经过Feed exports：https://docs.scrapy.org/en/latest/topics/feed-exports.html#topics-feed-exports）

三、Spiders总共提供了五种类：

#一、scrapy.spiders.Spider #scrapy.Spider等同于scrapy.spiders.Spider
#二、scrapy.spiders.CrawlSpider
#三、scrapy.spiders.XMLFeedSpider
#四、scrapy.spiders.CSVFeedSpider
#五、scrapy.spiders.SitemapSpider

四、导入使用

# -*- coding: utf-8 -*-
import scrapy
from scrapy.spiders import Spider,CrawlSpider,XMLFeedSpider,CSVFeedSpider,SitemapSpider

class AmazonSpider(scrapy.Spider): #自定义类，继承Spiders提供的基类
    name = 'amazon'
    allowed_domains = ['www.amazon.cn']
    start_urls = ['http://www.amazon.cn/']
    
    def parse(self, response):
        pass

五、class scrapy.spiders.Spider

这是最简单的spider类，任何其余的spider类都须要继承它（包含你本身定义的）。

该类不提供任何特殊的功能，它仅提供了一个默认的start_requests方法默认从start_urls中读取url地址发送requests请求，而且默认parse做为回调函数

class AmazonSpider(scrapy.Spider):
    name = 'amazon' 
    
    allowed_domains = ['www.amazon.cn'] 
    
    start_urls = ['http://www.amazon.cn/']
    
    custom_settings = {
        'BOT_NAME' : 'Egon_Spider_Amazon',
        'REQUEST_HEADERS' : {
          'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
          'Accept-Language': 'en',
        }
    }
    
    def parse(self, response):
        pass

#一、name = 'amazon' 
定义爬虫名，scrapy会根据该值定位爬虫程序
因此它必需要有且必须惟一（In Python 2 this must be ASCII only.）

#二、allowed_domains = ['www.amazon.cn'] 
定义容许爬取的域名，若是OffsiteMiddleware启动（默认就启动），
那么不属于该列表的域名及其子域名都不容许爬取
若是爬取的网址为：https://www.example.com/1.html，那就添加'example.com'到列表.

#三、start_urls = ['http://www.amazon.cn/']
若是没有指定url，就从该列表中读取url来生成第一个请求

#四、custom_settings
值为一个字典，定义一些配置信息，在运行爬虫程序时，这些配置会覆盖项目级别的配置
因此custom_settings必须被定义成一个类属性，因为settings会在类实例化前被加载

#五、settings
经过self.settings['配置项的名字']能够访问settings.py中的配置，若是本身定义了custom_settings仍是以本身的为准

#六、logger
日志名默认为spider的名字
self.logger.debug('=============>%s' %self.settings['BOT_NAME'])

#五、crawler：了解
该属性必须被定义到类方法from_crawler中

#六、from_crawler(crawler, *args, **kwargs)：了解
You probably won’t need to override this directly  because the default implementation acts as a proxy to the __init__() method, calling it with the given arguments args and named arguments kwargs.

#七、start_requests()
该方法用来发起第一个Requests请求，且必须返回一个可迭代的对象。它在爬虫程序打开时就被Scrapy调用，Scrapy只调用它一次。
默认从start_urls里取出每一个url来生成Request(url, dont_filter=True)

#针对参数dont_filter,请看自定义去重规则

若是你想要改变起始爬取的Requests，你就须要覆盖这个方法，例如你想要起始发送一个POST请求，以下
class MySpider(scrapy.Spider):
    name = 'myspider'

    def start_requests(self):
        return [scrapy.FormRequest("http://www.example.com/login",
                                   formdata={'user': 'john', 'pass': 'secret'},
                                   callback=self.logged_in)]

    def logged_in(self, response):
        # here you would extract links to follow and return Requests for
        # each of them, with another callback
        pass
        
#八、parse(response)
这是默认的回调函数，全部的回调函数必须返回an iterable of Request and/or dicts or Item objects.

#九、log(message[, level, component])：了解
Wrapper that sends a log message through the Spider’s logger, kept for backwards compatibility. For more information see Logging from Spiders.

#十、closed(reason)
爬虫程序结束时自动触发

去重规则应该多个爬虫共享的，但凡一个爬虫爬取了，其余都不要爬了，实现方式以下

#方法一：
1、新增类属性
visited=set() #类属性

2、回调函数parse方法内：
def parse(self, response):
    if response.url in self.visited:
        return None
    .......

    self.visited.add(response.url) 

#方法一改进：针对url可能过长，因此咱们存放url的hash值
def parse(self, response):
        url=md5(response.request.url)
    if url in self.visited:
        return None
    .......

    self.visited.add(url) 

#方法二：Scrapy自带去重功能
配置文件：
DUPEFILTER_CLASS = 'scrapy.dupefilter.RFPDupeFilter' #默认的去重规则帮咱们去重，去重规则在内存中
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，去重规则放文件中

scrapy自带去重规则默认为RFPDupeFilter，只须要咱们指定
Request(...,dont_filter=False) ，若是dont_filter=True则告诉Scrapy这个URL不参与去重。

#方法三：
咱们也能够仿照RFPDupeFilter自定义去重规则，

from scrapy.dupefilter import RFPDupeFilter，看源码，仿照BaseDupeFilter

#步骤一：在项目目录下自定义去重文件dup.py
class UrlFilter(object):
    def __init__(self):
        self.visited = set() #或者放到数据库

    @classmethod
    def from_settings(cls, settings):
        return cls()

    def request_seen(self, request):
        if request.url in self.visited:
            return True
        self.visited.add(request.url)

    def open(self):  # can return deferred
        pass

    def close(self, reason):  # can return a deferred
        pass

    def log(self, request, spider):  # log that a request has been filtered
        pass

#步骤二：配置文件settings.py：
DUPEFILTER_CLASS = '项目名.dup.UrlFilter'


# 源码分析：
from scrapy.core.scheduler import Scheduler
见Scheduler下的enqueue_request方法：self.df.request_seen(request)

去重规则：去除重复的url

#例一：
import scrapy

class MySpider(scrapy.Spider):
    name = 'example.com'
    allowed_domains = ['example.com']
    start_urls = [
        'http://www.example.com/1.html',
        'http://www.example.com/2.html',
        'http://www.example.com/3.html',
    ]

    def parse(self, response):
        self.logger.info('A response from %s just arrived!', response.url)
        
    
#例二：一个回调函数返回多个Requests和Items
import scrapy

class MySpider(scrapy.Spider):
    name = 'example.com'
    allowed_domains = ['example.com']
    start_urls = [
        'http://www.example.com/1.html',
        'http://www.example.com/2.html',
        'http://www.example.com/3.html',
    ]

    def parse(self, response):
        for h3 in response.xpath('//h3').extract():
            yield {"title": h3}

        for url in response.xpath('//a/@href').extract():
            yield scrapy.Request(url, callback=self.parse)
            
            
#例三：在start_requests()内直接指定起始爬取的urls，start_urls就没有用了，

import scrapy
from myproject.items import MyItem

class MySpider(scrapy.Spider):
    name = 'example.com'
    allowed_domains = ['example.com']

    def start_requests(self):
        yield scrapy.Request('http://www.example.com/1.html', self.parse)
        yield scrapy.Request('http://www.example.com/2.html', self.parse)
        yield scrapy.Request('http://www.example.com/3.html', self.parse)

    def parse(self, response):
        for h3 in response.xpath('//h3').extract():
            yield MyItem(title=h3)

        for url in response.xpath('//a/@href').extract():
            yield scrapy.Request(url, callback=self.parse)

例子

咱们可能须要在命令行为爬虫程序传递参数，好比传递初始的url，像这样
#命令行执行
scrapy crawl myspider -a category=electronics

#在__init__方法中能够接收外部传进来的参数
import scrapy

class MySpider(scrapy.Spider):
    name = 'myspider'

    def __init__(self, category=None, *args, **kwargs):
        super(MySpider, self).__init__(*args, **kwargs)
        self.start_urls = ['http://www.example.com/categories/%s' % category]
        #...

        
#注意接收的参数全都是字符串，若是想要结构化的数据，你须要用相似json.loads的方法

参数传递

六、其余通用Spiders：https://docs.scrapy.org/en/latest/topics/spiders.html#generic-spiders

六 Selectors

#1 //与/
#2 text
#三、extract与extract_first:从selector对象中解出内容
#四、属性：xpath的属性加前缀@
#四、嵌套查找
#五、设置默认值
#四、按照属性查找
#五、按照属性模糊查找
#六、正则表达式
#七、xpath相对路径
#八、带变量的xpath

response.selector.css()
response.selector.xpath()
可简写为
response.css()
response.xpath()

#1 //与/
response.xpath('//body/a/')#
response.css('div a::text')

>>> response.xpath('//body/a') #开头的//表明从整篇文档中寻找,body以后的/表明body的儿子
[]
>>> response.xpath('//body//a') #开头的//表明从整篇文档中寻找,body以后的//表明body的子子孙孙
[<Selector xpath='//body//a' data='<a href="image1.html">Name: My image 1 <'>, <Selector xpath='//body//a' data='<a href="image2.html">Name: My image 2 <'>, <Selector xpath='//body//a' data='<a href="
image3.html">Name: My image 3 <'>, <Selector xpath='//body//a' data='<a href="image4.html">Name: My image 4 <'>, <Selector xpath='//body//a' data='<a href="image5.html">Name: My image 5 <'>]

#2 text
>>> response.xpath('//body//a/text()')
>>> response.css('body a::text')

#三、extract与extract_first:从selector对象中解出内容
>>> response.xpath('//div/a/text()').extract()
['Name: My image 1 ', 'Name: My image 2 ', 'Name: My image 3 ', 'Name: My image 4 ', 'Name: My image 5 ']
>>> response.css('div a::text').extract()
['Name: My image 1 ', 'Name: My image 2 ', 'Name: My image 3 ', 'Name: My image 4 ', 'Name: My image 5 ']

>>> response.xpath('//div/a/text()').extract_first()
'Name: My image 1 '
>>> response.css('div a::text').extract_first()
'Name: My image 1 '

#四、属性：xpath的属性加前缀@
>>> response.xpath('//div/a/@href').extract_first()
'image1.html'
>>> response.css('div a::attr(href)').extract_first()
'image1.html'

#四、嵌套查找
>>> response.xpath('//div').css('a').xpath('@href').extract_first()
'image1.html'

#五、设置默认值
>>> response.xpath('//div[@id="xxx"]').extract_first(default="not found")
'not found'

#四、按照属性查找
response.xpath('//div[@id="images"]/a[@href="image3.html"]/text()').extract()
response.css('#images a[@href="image3.html"]/text()').extract()

#五、按照属性模糊查找
response.xpath('//a[contains(@href,"image")]/@href').extract()
response.css('a[href*="image"]::attr(href)').extract()

response.xpath('//a[contains(@href,"image")]/img/@src').extract()
response.css('a[href*="imag"] img::attr(src)').extract()

response.xpath('//*[@href="image1.html"]')
response.css('*[href="image1.html"]')

#六、正则表达式
response.xpath('//a/text()').re(r'Name: (.*)')
response.xpath('//a/text()').re_first(r'Name: (.*)')

#七、xpath相对路径
>>> res=response.xpath('//a[contains(@href,"3")]')[0]
>>> res.xpath('img')
[<Selector xpath='img' data='<img src="image3_thumb.jpg">'>]
>>> res.xpath('./img')
[<Selector xpath='./img' data='<img src="image3_thumb.jpg">'>]
>>> res.xpath('.//img')
[<Selector xpath='.//img' data='<img src="image3_thumb.jpg">'>]
>>> res.xpath('//img') #这就是从头开始扫描
[<Selector xpath='//img' data='<img src="image1_thumb.jpg">'>, <Selector xpath='//img' data='<img src="image2_thumb.jpg">'>, <Selector xpath='//img' data='<img src="image3_thumb.jpg">'>, <Selector xpa
th='//img' data='<img src="image4_thumb.jpg">'>, <Selector xpath='//img' data='<img src="image5_thumb.jpg">'>]

#八、带变量的xpath
>>> response.xpath('//div[@id=$xxx]/a/text()',xxx='images').extract_first()
'Name: My image 1 '
>>> response.xpath('//div[count(a)=$yyy]/@id',yyy=5).extract_first() #求有5个a标签的div的id
'images'

View Code

https://docs.scrapy.org/en/latest/topics/selectors.html

七 Items

https://docs.scrapy.org/en/latest/topics/items.html

八 Item Pipeline

#一：能够写多个Pipeline类
#一、若是优先级高的Pipeline的process_item返回一个值或者None，会自动传给下一个pipline的process_item,
#二、若是只想让第一个Pipeline执行，那得让第一个pipline的process_item抛出异常raise DropItem()

#三、能够用spider.name == '爬虫名' 来控制哪些爬虫用哪些pipeline

二：示范
from scrapy.exceptions import DropItem

class CustomPipeline(object):
    def __init__(self,v):
        self.value = v

    @classmethod
    def from_crawler(cls, crawler):
        """
        Scrapy会先经过getattr判断咱们是否自定义了from_crawler,有则调它来完
        成实例化
        """
        val = crawler.settings.getint('MMMM')
        return cls(val)

    def open_spider(self,spider):
        """
        爬虫刚启动时执行一次
        """
        print('000000')

    def close_spider(self,spider):
        """
        爬虫关闭时执行一次
        """
        print('111111')


    def process_item(self, item, spider):
        # 操做并进行持久化

        # 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()

自定义pipeline

#一、settings.py
HOST="127.0.0.1"
PORT=27017
USER="root"
PWD="123"
DB="amazon"
TABLE="goods"



ITEM_PIPELINES = {
   'Amazon.pipelines.CustomPipeline': 200,
}

#二、pipelines.py
class CustomPipeline(object):
    def __init__(self,host,port,user,pwd,db,table):
        self.host=host
        self.port=port
        self.user=user
        self.pwd=pwd
        self.db=db
        self.table=table

    @classmethod
    def from_crawler(cls, crawler):
        """
        Scrapy会先经过getattr判断咱们是否自定义了from_crawler,有则调它来完
        成实例化
        """
        HOST = crawler.settings.get('HOST')
        PORT = crawler.settings.get('PORT')
        USER = crawler.settings.get('USER')
        PWD = crawler.settings.get('PWD')
        DB = crawler.settings.get('DB')
        TABLE = crawler.settings.get('TABLE')
        return cls(HOST,PORT,USER,PWD,DB,TABLE)

    def open_spider(self,spider):
        """
        爬虫刚启动时执行一次
        """
        self.client = MongoClient('mongodb://%s:%s@%s:%s' %(self.user,self.pwd,self.host,self.port))

    def close_spider(self,spider):
        """
        爬虫关闭时执行一次
        """
        self.client.close()


    def process_item(self, item, spider):
        # 操做并进行持久化

        self.client[self.db][self.table].save(dict(item))

示范

https://docs.scrapy.org/en/latest/topics/item-pipeline.html

九 Dowloader Middeware

class DownMiddleware1(object):
    def process_request(self, request, spider):
        """
        请求须要被下载时，通过全部下载器中间件的process_request调用
        :param request: 
        :param spider: 
        :return:  
            None,继续后续中间件去下载；
            Response对象，中止process_request的执行，开始执行process_response
            Request对象，中止中间件的执行，将Request从新调度器
            raise IgnoreRequest异常，中止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：转交给其余中间件process_response
            Request 对象：中止中间件，request会被从新调度下载
            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：中止后续process_exception方法
            Request对象：中止中间件，request将会被从新调用下载
        """
        return None

下载器中间件

https://docs.scrapy.org/en/latest/topics/downloader-middleware.html

class DownMiddleware1(object):
    @staticmethod
    def get_proxy():
        return requests.get("http://127.0.0.1:5010/get/").text

    @staticmethod
    def delete_proxy(proxy):
        requests.get("http://127.0.0.1:5010/delete/?proxy={}".format(proxy))

    def process_request(self, request, spider):
        """
        请求须要被下载时，通过全部下载器中间件的process_request调用
        :param request:
        :param spider:
        :return:
            None,继续后续中间件去下载；
            Response对象，中止process_request的执行，开始执行process_response
            Request对象，中止中间件的执行，将Request从新调度器
            raise IgnoreRequest异常，中止process_request的执行，开始执行process_exception
        """

        if not hasattr(DownMiddleware1,'proxy_addr'):
            DownMiddleware1.proxy_addr = self.get_proxy()
        request.meta['download_timeout'] = 5
        request.meta["proxy"] = "http://" + self.proxy_addr

        print('元数据',request.meta)

        if request.meta.get('depth') == 10 or request.meta.get('retry_times') == 2:
            request.meta['depth'] = 0
            request.meta['retry_times']=0
            self.delete_proxy(self.proxy_addr)

            DownMiddleware1.proxy_addr=self.get_proxy()
            request.meta["proxy"] = "http://" + self.proxy_addr
            print('============>',request.meta)
            return request

        return None

View Code

十 Spider Middleware

class SpiderMiddleware(object):

    def process_spider_input(self,response, spider):
        """
        下载完成，执行，而后交给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

https://docs.scrapy.org/en/latest/topics/spider-middleware.html

十一 settings.py

# -*- 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，而且延迟下次秒数也应用在每一个域名
# CONCURRENT_REQUESTS_PER_DOMAIN = 2
# 单IP访问并发数，若是有值则忽略：CONCURRENT_REQUESTS_PER_DOMAIN，而且延迟下次秒数也应用在每一个IP
# CONCURRENT_REQUESTS_PER_IP = 3

# Disable cookies (enabled by default)
# 8. 是否支持cookie，cookiejar进行操做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，操做爬虫等...
#    使用telnet ip port ，而后经过命令操做
# 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. 爬虫容许的最大深度，能够经过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"链接"时间 latency，即：请求链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，以便之后使用
    
    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：全部请求均缓存，下次在请求直接访问原来的缓存便可
# 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，须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访问时有两种状况：
    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))
                )
    其余：
        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，而后交给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):
            '''
            请求须要被下载时，通过全部下载器中间件的process_request调用
            :param request:
            :param spider:
            :return:
                None,继续后续中间件去下载；
                Response对象，中止process_request的执行，开始执行process_response
                Request对象，中止中间件的执行，将Request从新调度器
                raise IgnoreRequest异常，中止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：转交给其余中间件process_response
                Request 对象：中止中间件，request会被从新调度下载
                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：中止后续process_exception方法
                Request对象：中止中间件，request将会被从新调用下载
            '''
            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.py

十二爬取亚马逊商品信息

1、
scrapy startproject Amazon
cd Amazon
scrapy genspider spider_goods www.amazon.cn

2、settings.py
ROBOTSTXT_OBEY = False
#请求头
DEFAULT_REQUEST_HEADERS = {
    'Referer':'https://www.amazon.cn/',
    'User-Agent':'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.75 Safari/537.36'
}
#打开注释
HTTPCACHE_ENABLED = True
HTTPCACHE_EXPIRATION_SECS = 0
HTTPCACHE_DIR = 'httpcache'
HTTPCACHE_IGNORE_HTTP_CODES = []
HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

3、items.py
class GoodsItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    #商品名字
    goods_name = scrapy.Field()
    #价钱
    goods_price = scrapy.Field()
    #配送方式
    delivery_method=scrapy.Field()

4、spider_goods.py
# -*- coding: utf-8 -*-
import scrapy

from Amazon.items import  GoodsItem
from scrapy.http import Request
from urllib.parse import urlencode

class SpiderGoodsSpider(scrapy.Spider):
    name = 'spider_goods'
    allowed_domains = ['www.amazon.cn']
    # start_urls = ['http://www.amazon.cn/']


    def __int__(self,keyword=None,*args,**kwargs):
        super(SpiderGoodsSpider).__init__(*args,**kwargs)
        self.keyword=keyword

    def start_requests(self):
        url='https://www.amazon.cn/s/ref=nb_sb_noss_1?'
        paramas={
            '__mk_zh_CN': '亚马逊网站',
            'url': 'search - alias = aps',
            'field-keywords': self.keyword
        }
        url=url+urlencode(paramas,encoding='utf-8')
        yield Request(url,callback=self.parse_index)


    def parse_index(self, response):
        print('解析索引页:%s' %response.url)

        urls=response.xpath('//*[contains(@id,"result_")]/div/div[3]/div[1]/a/@href').extract()
        for url in urls:
            yield Request(url,callback=self.parse_detail)

        next_url=response.urljoin(response.xpath('//*[@id="pagnNextLink"]/@href').extract_first())
        print('下一页的url',next_url)
        yield Request(next_url,callback=self.parse_index)

    def parse_detail(self,response):
        print('解析详情页:%s' %(response.url))

        item=GoodsItem()
        # 商品名字
        item['goods_name'] = response.xpath('//*[@id="productTitle"]/text()').extract_first().strip()
        # 价钱
        item['goods_price'] = response.xpath('//*[@id="priceblock_ourprice"]/text()').extract_first().strip()
        # 配送方式
        item['delivery_method'] = ''.join(response.xpath('//*[@id="ddmMerchantMessage"]//text()').extract())
        return item

5、自定义pipelines
#sql.py
import pymysql
import settings


MYSQL_HOST=settings.MYSQL_HOST
MYSQL_PORT=settings.MYSQL_PORT
MYSQL_USER=settings.MYSQL_USER
MYSQL_PWD=settings.MYSQL_PWD
MYSQL_DB=settings.MYSQL_DB

conn=pymysql.connect(
    host=MYSQL_HOST,
    port=int(MYSQL_PORT),
    user=MYSQL_USER,
    password=MYSQL_PWD,
    db=MYSQL_DB,
    charset='utf8'
)
cursor=conn.cursor()

class Mysql(object):
    @staticmethod
    def insert_tables_goods(goods_name,goods_price,deliver_mode):
        sql='insert into goods(goods_name,goods_price,delivery_method) values(%s,%s,%s)'
        cursor.execute(sql,args=(goods_name,goods_price,deliver_mode))
        conn.commit()

    @staticmethod
    def is_repeat(goods_name):
        sql='select count(1) from goods where goods_name=%s'
        cursor.execute(sql,args=(goods_name,))
        if cursor.fetchone()[0] >= 1:
            return True

if __name__ == '__main__':
    cursor.execute('select * from goods;')
    print(cursor.fetchall())


#pipelines.py
from Amazon.mysqlpipelines.sql import Mysql


class AmazonPipeline(object):
    def process_item(self, item, spider):
        goods_name=item['goods_name']
        goods_price=item['goods_price']
        delivery_mode=item['delivery_method']
        if not Mysql.is_repeat(goods_name):
            Mysql.insert_table_goods(goods_name,goods_price,delivery_mode)



6、建立数据库表
create database amazon charset utf8;
create table goods(
    id int primary key auto_increment,
    goods_name char(30),
    goods_price char(20),
    delivery_method varchar(50)
);

7、settings.py
MYSQL_HOST='localhost'
MYSQL_PORT='3306'
MYSQL_USER='root'
MYSQL_PWD='123'
MYSQL_DB='amazon'


#数字表明优先级程度（1-1000随意设置，数值越低，组件的优先级越高）
ITEM_PIPELINES = {
   'Amazon.mysqlpipelines.pipelines.mazonPipeline': 1,
}


#八、在项目目录下新建：entrypoint.py
from scrapy.cmdline import execute
execute(['scrapy', 'crawl', 'spider_goods','-a','keyword=iphone8'])

View Code

https://pan.baidu.com/s/1boCEBT1

1. 爬虫框架：scrapy 爬虫框架：scrapy
2. 爬虫框架scrapy
3. scrapy爬虫框架
4. 爬虫---scrapy框架
5. 爬虫-Scrapy框架
6. 爬虫框架：scrapy
7. Scrapy爬虫框架
8. 爬虫 scrapy框架
9. Scrapy框架-----爬虫
10. 06 爬虫框架：scrapy 爬虫框架：scrapy
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爬虫、框架scrapy

一 介绍

二 安装

三 命令行工具

四 项目结构以及爬虫应用简介

五 Spiders

六 Selectors

七 Items

八 Item Pipeline

九 Dowloader Middeware

十 Spider Middleware

十一 settings.py

十二 爬取亚马逊商品信息

一介绍

二安装

三命令行工具

四项目结构以及爬虫应用简介

十二爬取亚马逊商品信息