python-scrapy框架学习

时间  2020-11-16 标签 css html python 正则表达式 shell api app 框架 dom scrapy

Scrapy框架

Scrapy安装

正常安装会报错，主要是两个缘由css

0x01 升级pip3包

python -m pip install -U pip

0x02 手动安装依赖

须要手动安装 wheel、lxml、Twisted、pywin32html

pip3 install wheel

pip3 install lxml

pip3 install Twisted

pip3 install pywin32

0x03 安装Scrapy

pip3 install scrapy

Scrapy 进行项目管理

0x01 使用scrapy建立一个新的爬虫项目

mkdir Scrapy 

scrapy startproject myfirstpjt

cd myfirstpjt

image-20201110220849055

0x02 scrapy相关命令

命令分为两种，一种为全局命令，一种为项目命令python

全局命令不须要依赖Scrapy项目便可直接与性能，项目命令必须依赖项目正则表达式

在Scrapy项目所在目录外使用scrapy -h 显示全部全局命令shell

C:\Users\LENOVO>scrapy -h
Scrapy 2.4.0 - no active project

Usage:
  scrapy <command> [options] [args]

Available commands:
  bench         Run quick benchmark test
  commands
  fetch         Fetch a URL using the Scrapy downloader
  genspider     Generate new spider using pre-defined templates
  runspider     Run a self-contained spider (without creating a project)
  settings      Get settings values
  shell         Interactive scraping console
  startproject  Create new project
  version       Print Scrapy version
  view          Open URL in browser, as seen by Scrapy

  [ more ]      More commands available when run from project directory

Use "scrapy <command> -h" to see more info about a command

fetch

fetch命令主要用来显示爬虫爬取过程api

image-20201110224047794

0x03 选择器

支持 XPath CSS 选择器app

同时XPath选择器还有一个.re()方法用于经过正则表达式来提取数据框架

，不一样于使用.xpath()或者.css()方法，.re()方法返回unicode字符串的 列表，因此没法构造嵌套式的.re()调用dom

建立Scrapy项目

日常写小脚本或者项目就至关于白纸上写做文，而框架会集成一些常常用的东西将做文题变成填空题，大大减小了工做量scrapy

scrapy startproject 项目名称 (例如 todayMovie)

tree todayMovie

D:\pycharm\code\Scrapy>scrapy startproject todayMovie
New Scrapy project 'todayMovie', using template directory 'c:\python3.7\lib\site-packages\scrapy\templates\project', created in:
    D:\pycharm\code\Scrapy\todayMovie

You can start your first spider with:
    cd todayMovie
    scrapy genspider example example.com

D:\pycharm\code\Scrapy>tree todayMovie
文件夹 PATH 列表
卷序列号为 6858-7249
D:\PYCHARM\CODE\SCRAPY\TODAYMOVIE
└─todayMovie
    └─spiders

D:\pycharm\code\Scrapy>

0x01 使用 genspider参数新建基础爬虫

新建一个名为wuHanMovieSpider的爬虫脚本，脚本搜索的域为mtime.com

scrapy genspider wuHanMovieSpider mtime.com

image-20201112222835234

0x02 关于框架下的文件

scrapy.cfg

主要声明默认设置文件位置为todayMovie模块下的settings文件（setting.py），定义项目名为todayMovie

items.py文件的做用是定义爬虫最终须要哪些项，

pipelines.py文件的做用是扫尾。Scrapy爬虫爬取了网页中的内容 后，这些内容怎么处理就取决于pipelines.py如何设置

须要修改、填空的只有4个文件，它们 分别是items.py、settings.py、pipelines.py、wuHanMovieSpider.py。

其中 items.py决定爬取哪些项目，wuHanMovieSpider.py决定怎么爬， settings.py决定由谁去处理爬取的内容，pipelines.py决定爬取后的内容怎样处理

0x03 xpath选择器

selector = response.xpath('/html/body/div[@id='homeContentRegion']//text()')[0].extract()

extract() 返回选中内容的Unicode字符串。

关于xpath遍历文档树

符号 用途
/ 选中文档的根，通常为html
// 选中从当前位置开始全部子孙节点
./ 表示从当前节点提取，二次提取数据时会用到
. 选中当前节点，相对路径
.. 选中当前节点父节点，相对路径
ELEMENT 选中子节点中全部ELEMENT元素节点
//ELEMENT 选中子孙节点全部ELEMENT元素节点
* 选中全部元素子节点
text() 选中素有文本子节点
@ATTR 选中名为ATTR的属性节点
@* 选中全部属性节点
/@ATTR 获取节点属值
方法 用途
contains a[contains(@href,"test")] 查找href属性包含test字符的a标签
start-with a[start-with(@href,"http")] 查找href属性以http开头的a标签

举例

response.xpath('//a/text()') #选取全部a的文本

response.xpath('//div/*/img') #选取div孙节点的全部img

response.xpath('//p[contains(@class,'song')]') #选择class属性中含有‘song’的p元素

response.xpath('//a[contains(@data-pan,'M18_Index_review_short_movieName')]/text()')

response.xpath('//div/a | //div/p') 或者，页面中多是a多是p

selector = response.xpath('//a[contains(@href,"http://movie.mtime.com")]/text()').extract()

参考文章

http://www.javashuo.com/article/p-yqgmlgqj-dy.html

http://www.javashuo.com/article/p-wmhvcwio-no.html

实例 爬取天气预报

0x01 建立weather项目及基础爬虫

cd Scrapy\code
scrapy startproject weather
scrapy genspider beiJingSpider www.weather.com.cn/weather/101010100.shtml

0x02 修改items.py

class WeatherItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    cityDate = scrapy.Field()   #城市及日期
    week = scrapy.Field()   #星期
    temperature = scrapy.Field()    #温度
    weather = scrapy.Field()    #天气
    wind = scrapy.Field()   #风力

image-20201115232731688

0x03 scrapy shell

先使用scrapy shell命令来测试获取选择器，主要是看一下网站有没有反爬机制

scrapy shell https://www.tianqi.com/beijing/

image-20201115193319731

好比403就是禁止读取，而不是页面不存在。

简单的bypass就是添加UA和访问频率

0x04 简单的bypass

先准备一堆User-Agent放到resource.py利用random每次随机选择其中一个便可。

setp1：将准备好的resource.py放在settings.py的同级目录中

resource.py

#-*- coding:utf-8 -*-
UserAgents = [
  "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; AcooBrowser; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",
  "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; Acoo Browser; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506)",
  "Mozilla/4.0 (compatible; MSIE 7.0; AOL 9.5; AOLBuild 4337.35; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",
  "Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0; en-US)",
  "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 2.0.50727; Media Center PC 6.0)",
  "Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 1.0.3705; .NET CLR 1.1.4322)",
  "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.30)",
  "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 (KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)",
  "Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6",
  "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1",
  "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0",
  "Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5",
  "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.8) Gecko Fedora/1.9.0.8-1.fc10 Kazehakase/0.5.6",
  "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11",
  "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/535.20 (KHTML, like Gecko) Chrome/19.0.1036.7 Safari/535.20",
  "Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; fr) Presto/2.9.168 Version/11.52",
  "Mozilla/5.0 (Windows NT 10.0; …) Gecko/20100101 Firefox/76.0",
]

image-20201115194255599

step2：修改middlewares.py

导入random，UserAgents，UserAgentMiddleware

image-20201115194533687

最下面添加一个新类，新类继承于UserAgentMiddleware类

类中大体内容为提供每次请求时随机挑选的UA头

class CustomUserAgentMiddleware(UserAgentMiddleware):
    def __init__(self, user_agent='Scrapy'):
        # ua = "Mozilla/5.0 (Windows NT 10.0; …) Gecko/20100101 Firefox/76.0"
        ua = random.choice(UserAgents)
        self.user_agent = ua

image-20201115194746141

step3：修改settings.py

用CustomUserAgentMiddleware来替代 UserAgentMiddleware。

在settings.py中找到DOWNLOADER_MIDDLEWARES这个选项修改成以下图所示

image-20201115194917795

DOWNLOADER_MIDDLEWARES = {
    'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware': None,
    #'weather.middlewares.WeatherDownloaderMiddleware': 543,
    'weather.middlewares.CustomUserAgentMiddleware': 542,
}

step4：修改请求时间间隔

Scrapy在两次请求之间的时间设置是DOWNLOAD_DELAY，若是不考虑反爬那必然越小越好，值为30就是每隔30s像网站请求一次网页。

image-20201115195113089

ps：通常网站添加UA头便可bypass

image-20201115195421229

0x05 修改beiJingSpider.py

要获取的内容在class=day7这个div下，在这个div下锚点

image-20201115200409939

# 注意这里url最后要有/否则获取不到内容
scrapy shell https://tianqi.com/beijing/

selector = response.xpath('//div[@class="day7"]')

selector1 = selector.xpath('ul[@class="week"]/li')

image-20201115201806303

beiJingSpider.py

import scrapy
from weather.items import WeatherItem

class BeijingspiderSpider(scrapy.Spider):
    name = 'beiJingSpider'
    allowed_domains = ['https://www.tianqi.com/beijing/']
    start_urls = ['https://www.tianqi.com/beijing/']


    def parse(self, response):
        items = []
        city = response.xpath('//dd[@class="name"]/h2/text()').extract()
        Selector = response.xpath('//div[@class="day7"]')
        date = Selector.xpath('ul[@class="week"]/li/b/text()').extract()
        week = Selector.xpath('ul[@class="week"]/li/span/text()').extract()
        wind = Selector.xpath('ul[@class="txt"]/li/text()').extract()
        weather = Selector.xpath('ul[@class="txt txt2"]/li/text()').extract()
        temperature1 = Selector.xpath('div[@class="zxt_shuju"]/ul/li/span/text()')
        temperature2 = Selector.xpath('div[@class="zxt_shuju"]/ul/li/b/text()').extract()
        for i in range(7):
            item = WeatherItem()
            try:
                item['cityDate'] = city + date[i]
                item['week'] = week[i]
                item['temperature'] = temperature1[i] + ',' + temperature2[i]
                item['weather'] = weather[i]
                item['wind'] = wind[i]
            except IndexError as e:
                exit()
            items.append(item)
        return items

0x06 修改pipelines.py 处理Spider的结果

import time
import codecs

class WeatherPipeline:
    def process_item(self, item, spider):
        today = timw.strftime('%Y%m%d', time.localtime())
        fileName = today + '.txt'
        with codecs.open(fileName, 'a', 'utf-8') as fp:
            fp.write("%s \t %s \t %s \t %s \r\n" 
                     %(item['cityDate'],
                       item['week'],
                       item['temperature'],
                       item['weather'],
                       item['wind']))
        return item

0x07 修改settings.py

找到ITEM_PIPELINES去掉前面的注释

image-20201115210132863

0x08 爬取内容

回到weather项目下执行命令

scrapy crawl beiJingSpider

image-20201115232455439

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