python爬虫实例——用scarpy框架爬取全部新浪新闻
使用scrapy框架爬取新浪网导航页所有的大类,小类的子链接,取出链接页面新闻内容。
python版本3.5
注意点:spider文件中不写allowed domains,因为后面的子链接的url中跟不包含new.sina.com
爬虫运行报错:DEBUG: Filtered offsite request to 'weixin.sogou.com'
报错原因:
官方对这个的解释,是要request的地址和allow_domain里面的冲突,从而被过滤掉。
回头细查,在爬虫.py里面,明显将搜狗的域名写错,写成了“sougou.com”,而后面要爬取的url是“sogou.com/xxxxxx”,所以报错。
首先终端中运行 scrapy startproject sinanews (项目名)
然后spider文件夹中创建爬虫 scrapy genspider sina ‘new.sina.com’
tree 一下(已经写好的项目)
. ├── main.py ├── scrapy.cfg └── sinanews ├── __init__.py ├── __pycache__ │ ├── __init__.cpython-36.pyc │ ├── items.cpython-36.pyc │ ├── pipelines.cpython-36.pyc │ └── settings.cpython-36.pyc ├── items.py ├── middlewares.py ├── pipelines.py ├── settings.py └── spiders ├── __init__.py ├── __pycache__ │ ├── __init__.cpython-36.pyc │ └── sina.cpython-36.pyc └── sina.py
编辑items.py
定义好要爬取的url和标题名称(创建文件夹用) 以及文章内容和标题
import scrapy class SinanewsItem(scrapy.Item): # 大类的标题 和 url parentTitle = scrapy.Field() parentUrls = scrapy.Field() # 小类的标题 和 url subTitle= scrapy.Field() subUrls = scrapy.Field() # 小类目录存储路径 subFilename = scrapy.Field() # 小类下的子链接 sonUrls = scrapy.Field() # 文章标题和内容 head = scrapy.Field() content = scrapy.Field()
spider.py文件中全部代码
# -*- coding: utf-8 -*- import scrapy from ..items import SinanewsItem import os class SinaSpider(scrapy.Spider): name = 'sina' # allowed_domains = ['news.sina.com'] start_urls = ['http://news.sina.com.cn/guide'] def parse(self, response): items = [] # 所有大类的url 和 标题 parentUrls = response.xpath("//div[@id='tab01']/div/h3/a/@href").extract() parentTitle = response.xpath("//div[@id='tab01']/div/h3/a/text()").extract() # 所有小类的url 和 标题 subUrls = response.xpath("//div[@id='tab01']/div/ul/li/a/@href").extract() subTitle = response.xpath("//div[@id='tab01']/div/ul/li/a/text()").extract() # 爬取所有大类 for i in range(0,len(parentTitle)): # 指定大类目录的路径和目录名 parentFilename = "/Users/apple/Desktop/sina/" + parentTitle[i] # 如果目录不存在,则创建目录 if(not os.path.exists(parentFilename)): os.makedirs(parentFilename) # 爬取所有小类 for j in range(0,len(subUrls)): item = SinanewsItem() # 保存大类的title和urls item['parentTitle'] = parentTitle[i] item['parentUrls'] = parentUrls[i] # 检查小类的url是否 以同类别大类url开头,如果是返回True if_belong = subUrls[j].startswith(item['parentUrls']) # 如果属于本大类,将存储目录放在本大类目录下 if(if_belong): subFilename = parentFilename + '/' + subTitle[j] # 如果目录不存在,则创建目录 if(not os.path.exists(subFilename)): os.makedirs(subFilename) # 存储 小类url、title和filename字段数据 item['subUrls'] = subUrls[j] item['subTitle'] = subTitle[j] item['subFilename'] = subFilename items.append(item) # 发送每个小类的url的Request请求,得到Response连同包含meta数据 一同交给回调函数 second_parse方法处理 for item in items: yield scrapy.Request(url = item['subUrls'],meta={'meta_1':item},callback=self.second_parse) def second_parse(self,response): # 提取每次Response的meta数据 meta_1 = response.meta['meta_1'] # 取出小类里面的所有子链接 sonUrls = response.xpath('//a/@href').extract() items = [] for i in range(0,len(sonUrls)): # 检查每个链接是否以大类url开头、以shtml结尾,如果是返回True if_belong = sonUrls[i].endswith('.shtml') and sonUrls[i].startswith(meta_1['parentUrls']) # 如果属于本大类,获取字段值放在同一个item下便于传输 if(if_belong): item = SinanewsItem() item['parentTitle'] = meta_1['parentTitle'] item['parentUrls'] = meta_1['parentUrls'] item['subUrls'] = meta_1['subUrls'] item['subTitle'] = meta_1['subTitle'] item['subFilename'] = meta_1['subFilename'] item['sonUrls'] = sonUrls[i] items.append(item) # 发送每个小类下子链接url的Request请求,得到response后连同包含meta数据 一同交给回调函数 detail_parse for item in items: yield scrapy.Request(url=item['sonUrls'],meta={'meta_2':item},callback=self.detail_parse) # 数据解析方法,获取文章标题和内容 def detail_parse(self,response): item = response.meta['meta_2'] content = "" head = response.xpath('//h1[@class="main-title"]/text()').extract() content_list = response.xpath("//div[@class='article']//p/text()").extract() # 将p标签里的文本内容合并到一起 for content_one in content_list: content += content_one item['head'] = head item['content'] = content yield item
pipelines.py文件全部代码
# -*- 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 SinanewsSpiderMiddleware(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. @classmethod def from_crawler(cls, crawler): # This method is used by Scrapy to create your spiders. s = cls() crawler.signals.connect(s.spider_opened, signal=signals.spider_opened) return s 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. return None 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. 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 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). for r in start_requests: yield r def spider_opened(self, spider): spider.logger.info('Spider opened: %s' % spider.name) class SinanewsDownloaderMiddleware(object): # Not all methods need to be defined. If a method is not defined, # scrapy acts as if the downloader middleware does not modify the # passed objects. @classmethod def from_crawler(cls, crawler): # This method is used by Scrapy to create your spiders. s = cls() crawler.signals.connect(s.spider_opened, signal=signals.spider_opened) 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 return None 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 def spider_opened(self, spider): spider.logger.info('Spider opened: %s' % spider.name)
setting.py中打开
ITEM_PIPELINES = { 'sinanews.pipelines.SinanewsPipeline': 300, }
并将遵循robotstxt协议注释,否则有些网站怕不下来
# ROBOTSTXT_OBEY = True
然后随机设置几个user-agent