Scrapy爬蟲(chóng)Response子類(lèi)在應(yīng)用中的問(wèn)題解析
正文
今天用scrapy爬取壁紙的時(shí)候(url:http://pic.netbian.com/4kmein...)絮叨了一些問(wèn)題,記錄下來(lái),供后世探討,以史為鑒。**
因?yàn)榫W(wǎng)站是動(dòng)態(tài)渲染的,所以選擇scrapy對(duì)接selenium(scrapy抓取網(wǎng)頁(yè)的方式和requests庫(kù)相似,都是直接模擬HTTP請(qǐng)求,而Scrapy也不能抓取JavaScript動(dòng)態(tài)渲染的網(wǎng)頁(yè)。)
所以在Downloader Middlewares中需要得到Request并且返回一個(gè)Response,問(wèn)題出在Response,通過(guò)查看官方文檔發(fā)現(xiàn)class scrapy.http.Response(url[, status=200, headers=None, body=b'', flags=None, request=None]),隨即通過(guò)from scrapy.http import Response導(dǎo)入Response
輸入scrapy crawl girl得到如下錯(cuò)誤:
*results=response.xpath('//[@id="main"]/div[3]/ul/lia/img')
raise NotSupported("Response content isn't text")
scrapy.exceptions.NotSupported: Response content isn't text**
檢查相關(guān)代碼:
# middlewares.py from scrapy import signals from scrapy.http import Response from scrapy.exceptions import IgnoreRequest import selenium from selenium.webdriver.common.by import By from selenium.webdriver.support.ui import WebDriverWait from selenium.webdriver.support import expected_conditions as EC class Pic4KgirlDownloaderMiddleware(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. 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 try: self.browser=selenium.webdriver.Chrome() self.wait=WebDriverWait(self.browser,10) self.browser.get(request.url) self.wait.until(EC.presence_of_element_located((By.CSS_SELECTOR, '#main > div.page > a:nth-child(10)'))) return Response(url=request.url,status=200,request=request,body=self.browser.page_source.encode('utf-8')) #except: #raise IgnoreRequest() finally: self.browser.close()
推斷問(wèn)題出在:
return Response(url=request.url,status=200,request=request,body=self.browser.page_source.encode('utf-8'))
查看Response類(lèi)的定義
@property def text(self): """For subclasses of TextResponse, this will return the body as text (unicode object in Python 2 and str in Python 3) """ raise AttributeError("Response content isn't text") def css(self, *a, **kw): """Shortcut method implemented only by responses whose content is text (subclasses of TextResponse). """ raise NotSupported("Response content isn't text") def xpath(self, *a, **kw): """Shortcut method implemented only by responses whose content is text (subclasses of TextResponse). """ raise NotSupported("Response content isn't text")
說(shuō)明Response類(lèi)不可以被直接使用,需要被繼承重寫(xiě)方法后才能使用
響應(yīng)子類(lèi)
**TextResponse對(duì)象** class scrapy.http.TextResponse(url[, encoding[, ...]]) **HtmlResponse對(duì)象** class scrapy.http.HtmlResponse(url[, ...]) **XmlResponse對(duì)象** class scrapy.http.XmlResponse(url [,... ] )
舉例觀察TextResponse的定義from scrapy.http import TextResponse
導(dǎo)入TextResponse發(fā)現(xiàn)
class TextResponse(Response): _DEFAULT_ENCODING = 'ascii' def __init__(self, *args, **kwargs): self._encoding = kwargs.pop('encoding', None) self._cached_benc = None self._cached_ubody = None self._cached_selector = None super(TextResponse, self).__init__(*args, **kwargs)
其中xpath方法已經(jīng)被重寫(xiě)
@property def selector(self): from scrapy.selector import Selector if self._cached_selector is None: self._cached_selector = Selector(self) return self._cached_selector def xpath(self, query, **kwargs): return self.selector.xpath(query, **kwargs) def css(self, query): return self.selector.css(query)
所以用戶想要調(diào)用Response類(lèi),必須選擇調(diào)用其子類(lèi),并且重寫(xiě)部分方法
Scrapy爬蟲(chóng)入門(mén)教程十一 Request和Response(請(qǐng)求和響應(yīng))
scrapy文檔:https://doc.scrapy.org/en/lat...
中文翻譯文檔:http://www.dbjr.com.cn/article/248161.htm
以上就是Scrapy爬蟲(chóng)Response子類(lèi)在應(yīng)用中的問(wèn)題解析的詳細(xì)內(nèi)容,更多關(guān)于Scrapy爬蟲(chóng)Response子類(lèi)應(yīng)用的資料請(qǐng)關(guān)注腳本之家其它相關(guān)文章!
相關(guān)文章
Python數(shù)學(xué)建模PuLP庫(kù)線性規(guī)劃實(shí)際案例編程詳解
本節(jié)以一個(gè)實(shí)際數(shù)學(xué)建模案例,來(lái)為大家講解PuLP求解線性規(guī)劃問(wèn)題的建模與編程。來(lái)鞏固加深大家對(duì)Python數(shù)學(xué)建模PuLP庫(kù)線性規(guī)劃的運(yùn)用理解2021-10-10python 6.7 編寫(xiě)printTable()函數(shù)表格打印(完整代碼)
這篇文章主要介紹了python 6.7 編寫(xiě)一個(gè)名為printTable()的函數(shù) 表格打印,本文通過(guò)實(shí)例代碼給大家介紹的非常詳細(xì),對(duì)大家的學(xué)習(xí)或工作具有一定的參考借鑒價(jià)值,需要的朋友可以參考下2020-03-03python tkinter 設(shè)置窗口大小不可縮放實(shí)例
這篇文章主要介紹了python tkinter 設(shè)置窗口大小不可縮放實(shí)例,具有很好的參考價(jià)值,希望對(duì)大家有所幫助。一起跟隨小編過(guò)來(lái)看看吧2020-03-03解決tensorflow打印tensor有省略號(hào)的問(wèn)題
今天小編就為大家分享一篇解決tensorflow打印tensor有省略號(hào)的問(wèn)題,具有很好的參考價(jià)值,希望對(duì)大家有所幫助。一起跟隨小編過(guò)來(lái)看看吧2020-02-02詳解Python使用apscheduler定時(shí)執(zhí)行任務(wù)
在平常的工作中幾乎有一半的功能模塊都需要定時(shí)任務(wù)來(lái)推動(dòng),例如項(xiàng)目中有一個(gè)定時(shí)統(tǒng)計(jì)程序,定時(shí)爬出網(wǎng)站的URL程序,定時(shí)檢測(cè)釣魚(yú)網(wǎng)站的程序等等,都涉及到了關(guān)于定時(shí)任務(wù)的問(wèn)題,所以就找到了python的定時(shí)任務(wù)模塊2022-03-03PyQt5 實(shí)現(xiàn)字體大小自適應(yīng)分辨率的方法
今天小編就為大家分享一篇PyQt5 實(shí)現(xiàn)字體大小自適應(yīng)分辨率的方法,具有很好的參考價(jià)值,希望對(duì)大家有所幫助。一起跟隨小編過(guò)來(lái)看看吧2019-06-06