scrapy與selenium結(jié)合爬取數(shù)據(jù)(爬取動(dòng)態(tài)網(wǎng)站)的示例代碼
scrapy框架只能爬取靜態(tài)網(wǎng)站。如需爬取動(dòng)態(tài)網(wǎng)站,需要結(jié)合著selenium進(jìn)行js的渲染,才能獲取到動(dòng)態(tài)加載的數(shù)據(jù)。
如何通過selenium請(qǐng)求url,而不再通過下載器Downloader去請(qǐng)求這個(gè)url?
方法:在request對(duì)象通過中間件的時(shí)候,在中間件內(nèi)部開始使用selenium去請(qǐng)求url,并且會(huì)得到url對(duì)應(yīng)的源碼,然后再將 源 代碼通過response對(duì)象返回,直接交給process_response()進(jìn)行處理,再交給引擎。過程中相當(dāng)于后續(xù)中間件的process_request()以及Downloader都跳過了。
相關(guān)的配置:
1、scrapy環(huán)境中安裝selenium:pip install selenium
2、確保python環(huán)境中有phantomJS(無頭瀏覽器)
對(duì)于selenium的主要操作是下載中間件部分如下圖:
代碼如下
middlewares.py代碼:
注意:自定義下載中間件,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) *********************下面是相應(yīng)是自定義的下載中間件的替換代碼************************** class SeleniumTaobaoDownloaderMiddleware(object): # 將driver創(chuàng)建在中間件的初始化方法中,適合項(xiàng)目中只有一個(gè)爬蟲。 # 爬蟲項(xiàng)目中有多個(gè)爬蟲文件的話,將driver對(duì)象的創(chuàng)建放在每一個(gè)爬蟲文件中。 # def __init__(self): # # 在scrapy中創(chuàng)建driver對(duì)象,盡可能少的創(chuàng)建該對(duì)象。 # # 1. 在初始化方法中創(chuàng)建driver對(duì)象; # # 2. 在open_spider中創(chuàng)建deriver對(duì)象; # # 3. 不要將driver對(duì)象的創(chuàng)建放在process_request(); # option = FirefoxOptions() # option.headless = True # self.driver = webdriver.Firefox(options=option) # 參數(shù)spider就是TaobaoSpider()類的對(duì)象 def process_request(self, request, spider): if spider.name == "taobao": spider.driver.get(request.url) # 由于淘寶的頁面數(shù)據(jù)加載需要進(jìn)行滾動(dòng),但并不是所有js動(dòng)態(tài)數(shù)據(jù)都需要滾動(dòng)。 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 # 將源代碼構(gòu)造成為一個(gè)Response對(duì)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 代碼如下:
# -*- coding: utf-8 -*- import scrapy from selenium import webdriver from selenium.webdriver import FirefoxOptions class TaobaoSpider(scrapy.Spider): """ scrapy框架只能爬取靜態(tài)網(wǎng)站。如需爬取動(dòng)態(tài)網(wǎng)站,需要結(jié)合著selenium進(jìn)行js的渲染,才能獲取到動(dòng)態(tài)加載的數(shù)據(jù)。 如何通過selenium請(qǐng)求url,而不再通過下載器Downloader去請(qǐng)求這個(gè)url? 方法:在request對(duì)象通過中間件的時(shí)候,在中間件內(nèi)部開始使用selenium去請(qǐng)求url,并且會(huì)得到url對(duì)應(yīng)的源碼,然后再將源代碼通過response對(duì)象返回,直接交給process_response()進(jìn)行處理,再交給引擎。過程中相當(dāng)于后續(xù)中間件的process_request()以及Downloader都跳過了。 """ 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): # 在初始化淘寶對(duì)象時(shí),創(chuàng)建driver super(TaobaoSpider, self).__init__(name='taobao') option = FirefoxOptions() option.headless = True self.driver = webdriver.Firefox(options=option) def parse(self, response): """ 提取列表頁的商品標(biāo)題和價(jià)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代碼如下圖:
關(guān)于代碼中提到的初始化driver的位置有以下兩種情況:
1、只存在一個(gè)爬蟲文件的話,driver初始化函數(shù)可以定義在middlewares.py的自定義中間件中(如上述代碼注釋初始化部分)也可以在爬蟲文件中自定義(如上述代碼在爬蟲文件中初始化)。
注意:如果只有一個(gè)爬蟲文件就不需要在自定義的process_requsests中判斷是哪一個(gè)爬蟲項(xiàng)目然后分別請(qǐng)求!
2、如果存在兩個(gè)或兩個(gè)以上爬蟲項(xiàng)目(如下圖項(xiàng)目結(jié)構(gòu))的時(shí)候,需要將driver的初始化函數(shù)定義在各自的爬蟲項(xiàng)目文件下(如上述代碼),同時(shí)需要在process_requsests判斷是那個(gè)爬蟲項(xiàng)目的請(qǐng)求!!
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