Python使用Scrapy框架爬取数据存入CSV文件(Python爬虫实战4)

2018-02-26 08:14:51来源:cnblogs.com作者:HappyLab人点击

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1. Scrapy框架

  Scrapy是python下实现爬虫功能的框架,能够将数据解析、数据处理、数据存储合为一体功能的爬虫框架。

2. Scrapy安装

1. 安装依赖包

yum install gcc libffi-devel python-devel openssl-devel -yyum install libxslt-devel -y

 2. 安装scrapy

pip install scrapy
pip install twisted==13.1.0

 注意事项:scrapy和twisted存在兼容性问题,如果安装twisted版本过高,运行scrapy startproject project_name的时候会提示报错,安装twisted==13.1.0即可。

3. 基于Scrapy爬取数据并存入到CSV

3.1. 爬虫目标,获取简书中热门专题的数据信息,站点为https://www.jianshu.com/recommendations/collections,点击"热门"是我们需要爬取的站点,该站点使用了AJAX异步加载技术,通过F12键——Network——XHR,并翻页获取到页面URL地址为https://www.jianshu.com/recommendations/collections?page=2&order_by=hot,通过修改page=后面的数值即可访问多页的数据,如下图:

3.2. 爬取内容

  需要爬取专题的内容包括:专题内容、专题描述、收录文章数、关注人数,Scrapy使用xpath来清洗所需的数据,编写爬虫过程中可以手动通过lxml中的xpath获取数据,确认无误后再将其写入到scrapy代码中,区别点在于,scrapy需要使用extract()函数才能将数据提取出来。

3.3 创建爬虫项目

[root@HappyLau jianshu_hot_topic]# scrapy startproject jianshu_hot_topic#项目目录结构如下:[root@HappyLau python]# tree jianshu_hot_topicjianshu_hot_topic├── jianshu_hot_topic│   ├── __init__.py│   ├── __init__.pyc│   ├── items.py│   ├── items.pyc│   ├── middlewares.py│   ├── pipelines.py│   ├── pipelines.pyc│   ├── settings.py│   ├── settings.pyc│   └── spiders│       ├── collection.py│       ├── collection.pyc│       ├── __init__.py│       ├── __init__.pyc│       ├── jianshu_hot_topic_spider.py    #手动创建文件,用于爬虫数据提取│       └── jianshu_hot_topic_spider.pyc└── scrapy.cfg2 directories, 16 files[root@HappyLau python]# 

 3.4 代码内容

1. items.py代码内容,定义需要爬取数据字段# -*- coding: utf-8 -*-# Define here the models for your scraped items## See documentation in:# https://doc.scrapy.org/en/latest/topics/items.htmlimport scrapyfrom scrapy import Itemfrom scrapy import Fieldclass JianshuHotTopicItem(scrapy.Item):	'''	@scrapy.item,继承父类scrapy.Item的属性和方法,该类用于定义需要爬取数据的子段	'''	collection_name = Field()	collection_description = Field()	collection_article_count = Field()	collection_attention_count = Field()2. piders/jianshu_hot_topic_spider.py代码内容,实现数据获取的代码逻辑,通过xpath实现[root@HappyLau jianshu_hot_topic]# cat spiders/jianshu_hot_topic_spider.py#_*_ coding:utf8 _*_import randomfrom time import sleepfrom scrapy.spiders import CrawlSpiderfrom scrapy.selector import Selectorfrom scrapy.http import Requestfrom jianshu_hot_topic.items import JianshuHotTopicItem class jianshu_hot_topic(CrawlSpider):	'''	简书专题数据爬取,获取url地址中特定的子段信息	'''	name = "jianshu_hot_topic"	start_urls = ["https://www.jianshu.com/recommendations/collections?page=2&order_by=hot"]	def parse(self,response):		'''		@params:response,提取response中特定字段信息		'''		item = JianshuHotTopicItem()		selector = Selector(response)		collections = selector.xpath('//div[@class="col-xs-8"]')for collection in collections:collection_name = collection.xpath('div/a/h4/text()').extract()[0].strip()                	collection_description = collection.xpath('div/a/p/text()').extract()[0].strip()                	collection_article_count = collection.xpath('div/div/a/text()').extract()[0].strip().replace('篇文章','')                	collection_attention_count = collection.xpath('div/div/text()').extract()[0].strip().replace("人关注",'').replace("· ",'')	item['collection_name'] = collection_nameitem['collection_description'] = collection_descriptionitem['collection_article_count'] = collection_article_count item['collection_attention_count'] = collection_attention_countyield itemurls = ['https://www.jianshu.com/recommendations/collections?page={}&order_by=hot'.format(str(i)) for i in range(3,11)]		for url in urls:sleep(random.randint(2,7))yield Request(url,callback=self.parse)3. pipelines文件内容,定义数据存储的方式,此处定义数据存储的逻辑,可以将数据存储载MySQL数据库,MongoDB数据库,文件,CSV,Excel等存储介质中,如下以存储载CSV为例:[root@HappyLau jianshu_hot_topic]# cat pipelines.py# -*- 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.htmlimport csv class JianshuHotTopicPipeline(object):    def process_item(self, item, spider):    	f = file('/root/zhuanti.csv','a+')	writer = csv.writer(f)	writer.writerow((item['collection_name'],item['collection_description'],item['collection_article_count'],item['collection_attention_count']))        return item4. 修改settings文件,ITEM_PIPELINES = {     'jianshu_hot_topic.pipelines.JianshuHotTopicPipeline': 300,}

 3.5 运行scrapy爬虫

  返回到项目scrapy项目创建所在目录,运行scrapy crawl spider_name即可,如下:

[root@HappyLau jianshu_hot_topic]# pwd/root/python/jianshu_hot_topic[root@HappyLau jianshu_hot_topic]# scrapy crawl jianshu_hot_topic2018-02-24 19:12:23 [scrapy.utils.log] INFO: Scrapy 1.5.0 started (bot: jianshu_hot_topic)2018-02-24 19:12:23 [scrapy.utils.log] INFO: Versions: lxml 3.2.1.0, libxml2 2.9.1, cssselect 1.0.3, parsel 1.4.0, w3lib 1.19.0, Twisted 13.1.0, Python 2.7.5 (default, Aug  4 2017, 00:39:18) - [GCC 4.8.5 20150623 (Red Hat 4.8.5-16)], pyOpenSSL 0.13.1 (OpenSSL 1.0.1e-fips 11 Feb 2013), cryptography 1.7.2, Platform Linux-3.10.0-693.el7.x86_64-x86_64-with-centos-7.4.1708-Core2018-02-24 19:12:23 [scrapy.crawler] INFO: Overridden settings: {'NEWSPIDER_MODULE': 'jianshu_hot_topic.spiders', 'SPIDER_MODULES': ['jianshu_hot_topic.spiders'], 'ROBOTSTXT_OBEY': True, 'USER_AGENT': 'Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0', 'BOT_NAME': 'jianshu_hot_topic'}

 查看/root/zhuanti.csv中的数据,即可实现。

4. 遇到的问题总结

1. twisted版本不见容,安装过新的版本导致,安装Twisted (13.1.0)即可

2. 中文数据无法写入,提示'ascii'错误,通过设置python的encoding为utf即可,如下:

>>> import sys>>> sys.getdefaultencoding()'ascii'>>> reload(sys)<module 'sys' (built-in)>>>> sys.setdefaultencoding('utf8')>>> sys.getdefaultencoding()'utf8'

 3. 爬虫无法获取站点数据,由于headers导致,载settings.py文件中添加USER_AGENT变量,如:

USER_AGENT="Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0"

 Scrapy使用过程中可能会遇到结果执行失败或者结果执行不符合预期,其现实的logs非常详细,通过观察日志内容,并结合代码+网上搜索资料即可解决。

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