scrapy与selenium结合爬取数据(爬取动态网站)的示例代码
scrapy框架只能爬取静态网站。如需爬取动态网站,需要结合着selenium进行js的渲染,才能获取到动态加载的数据。
如何通过selenium请求url,而不再通过下载器Downloader去请求这个url?
方法:在request对象通过中间件的时候,在中间件内部开始使用selenium去请求url,并且会得到url对应的源码,然后再将 源 代码通过response对象返回,直接交给process_response()进行处理,再交给引擎。过程中相当于后续中间件的process_request()以及Downloader都跳过了。
相关的配置:
1、scrapy环境中安装selenium:pip install selenium
2、确保python环境中有phantomJS(无头浏览器)
对于selenium的主要操作是下载中间件部分如下图:
代码如下
middlewares.py代码:
注意:自定义下载中间件,采用selenium的方式!!
# -*- 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 from selenium import webdriver from selenium.webdriver import FirefoxOptions from scrapy.http import HtmlResponse, Response import time class TaobaospiderSpiderMiddleware(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 TaobaospiderDownloaderMiddleware(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) *********************下面是相应是自定义的下载中间件的替换代码************************** class SeleniumTaobaoDownloaderMiddleware(object): # 将driver创建在中间件的初始化方法中,适合项目中只有一个爬虫。 # 爬虫项目中有多个爬虫文件的话,将driver对象的创建放在每一个爬虫文件中。 # def __init__(self): # # 在scrapy中创建driver对象,尽可能少的创建该对象。 # # 1. 在初始化方法中创建driver对象; # # 2. 在open_spider中创建deriver对象; # # 3. 不要将driver对象的创建放在process_request(); # option = FirefoxOptions() # option.headless = True # self.driver = webdriver.Firefox(options=option) # 参数spider就是TaobaoSpider()类的对象 def process_request(self, request, spider): if spider.name == "taobao": spider.driver.get(request.url) # 由于淘宝的页面数据加载需要进行滚动,但并不是所有js动态数据都需要滚动。 for x in range(1, 11, 2): height = float(x) / 10 js = "document.documentElement.scrollTop = document.documentElement.scrollHeight * %f" % height spider.driver.execute_script(js) time.sleep(0.2) origin_code = spider.driver.page_source # 将源代码构造成为一个Response对象,并返回。 res = HtmlResponse(url=request.url, encoding='utf8', body=origin_code, request=request) # res = Response(url=request.url, body=bytes(origin_code), request=request) return res if spider.name == 'bole': request.cookies = {} request.headers.setDefault('User-Agent','') return None def process_response(self, request, response, spider): print(response.url, response.status) return response
taobao.py 代码如下:
# -*- coding: utf-8 -*- import scrapy from selenium import webdriver from selenium.webdriver import FirefoxOptions class TaobaoSpider(scrapy.Spider): """ scrapy框架只能爬取静态网站。如需爬取动态网站,需要结合着selenium进行js的渲染,才能获取到动态加载的数据。 如何通过selenium请求url,而不再通过下载器Downloader去请求这个url? 方法:在request对象通过中间件的时候,在中间件内部开始使用selenium去请求url,并且会得到url对应的源码,然后再将源代码通过response对象返回,直接交给process_response()进行处理,再交给引擎。过程中相当于后续中间件的process_request()以及Downloader都跳过了。 """ name = 'taobao' allowed_domains = ['taobao.com'] start_urls = ['https://s.taobao.com/search?q=%E7%AC%94%E8%AE%B0%E6%9C%AC%E7%94%B5%E8%84%91&imgfile=&commend=all&ssid=s5-e&search_type=item&sourceId=tb.index&spm=a21bo.2017.201856-taobao-item.1&ie=utf8&initiative_id=tbindexz_20170306'] def __init__(self): # 在初始化淘宝对象时,创建driver super(TaobaoSpider, self).__init__(name='taobao') option = FirefoxOptions() option.headless = True self.driver = webdriver.Firefox(options=option) def parse(self, response): """ 提取列表页的商品标题和价格 :param response: :return: """ info_divs = response.xpath('//div[@class="info-cont"]') print(len(info_divs)) for div in info_divs: title = div.xpath('.//a[@class="product-title"]/@title').extract_first('') price = div.xpath('.//span[contains(@class, "g_price")]/strong/text()').extract_first('') print(title, price)
settings.py代码如下图:
关于代码中提到的初始化driver的位置有以下两种情况:
1、只存在一个爬虫文件的话,driver初始化函数可以定义在middlewares.py的自定义中间件中(如上述代码注释初始化部分)也可以在爬虫文件中自定义(如上述代码在爬虫文件中初始化)。
注意:如果只有一个爬虫文件就不需要在自定义的process_requsests中判断是哪一个爬虫项目然后分别请求!
2、如果存在两个或两个以上爬虫项目(如下图项目结构)的时候,需要将driver的初始化函数定义在各自的爬虫项目文件下(如上述代码),同时需要在process_requsests判断是那个爬虫项目的请求!!
到此这篇关于scrapy与selenium结合爬取数据的示例代码的文章就介绍到这了,更多相关scrapy selenium爬取数据内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家!
最新评论