第十二章 Scrapy：Python3下的第一次運行測試

1，引言

《Scrapy的架構初探》一文講解了Scrapy的架構，本文就實際來安裝運行一下Scrapy爬蟲。本文以官網的tutorial作為例子，完整的代碼可以在github上下載。

2，運行環境配置

• 本次測試的環境是：Windows10， Python3.4.3 32bit
• 安裝Scrapy ： $ pip install Scrapy #實際安裝時，由於伺服器狀態的不穩定，出現好幾次中途退出的情況

3，編寫運行第一個Scrapy爬蟲

3.1. 生成一個新項目：tutorial

$ scrapy startproject tutorialn

項目目錄結構如下：

3.2. 定義要抓取的item

# -*- coding: utf-8 -*-nn# Define here the models for your scraped itemsn#n# See documentation in:n# http://doc.scrapy.org/en/latest/topics/items.htmlnnimport scrapynnclass DmozItem(scrapy.Item):n title = scrapy.Field()n link = scrapy.Field()n desc = scrapy.Field()n

3.3. 定義Spider

import scrapynfrom tutorial.items import DmozItemnnclass DmozSpider(scrapy.Spider):n name = "dmoz"n allowed_domains = ["dmoz.org"]n start_urls = [n "http://www.dmoz.org/Computers/Programming/Languages/Python/Books/",n "http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/"n ]nn def parse(self, response):n for sel in response.xpath(//ul/li):n item = DmozItem()n item[title] = sel.xpath(a/text()).extract()n item[link] = sel.xpath(a/@href).extract()n item[desc] = sel.xpath(text()).extract()n yield itemn

3.4. 運行

$ scrapy crawl dmoz -o item.jsonn

1) 結果報錯：

A) ImportError: cannot import name _win32stdio

B) ImportError: No module named win32api

2) 查錯過程：查看官方的FAQ和stackoverflow上的信息，原來是scrapy在python3上測試還不充分，還有小問題。

3) 解決過程：

A) 需要手工去下載twisted/internet下的 _win32stdio 和 _pollingfile，存放到python目錄的libsitepackagestwistedinternet下

B) 下載並安裝pywin32

再次運行，成功！在控制台上可以看到scrapy的輸出信息，待運行完成退出後，到項目目錄打開結果文件items.json， 可以看到裡面以json格式存儲的爬取結果。

[n{"title": [" About "], "desc": [" ", " "], "link": ["/docs/en/about.html"]},n{"title": [" Become an Editor "], "desc": [" ", " "], "link": ["/docs/en/help/become.html"]},n{"title": [" Suggest a Site "], "desc": [" ", " "], "link": ["/docs/en/add.html"]},n{"title": [" Help "], "desc": [" ", " "], "link": ["/docs/en/help/helpmain.html"]},n{"title": [" Login "], "desc": [" ", " "], "link": ["/editors/"]},n{"title": [], "desc": [" ", " Share via Facebook "], "link": []},n{"title": [], "desc": [" ", " Share via Twitter "], "link": []},n{"title": [], "desc": [" ", " Share via LinkedIn "], "link": []},n{"title": [], "desc": [" ", " Share via e-Mail "], "link": []},n{"title": [], "desc": [" ", " "], "link": []},n{"title": [], "desc": [" ", " "], "link": []},n{"title": [" About "], "desc": [" ", " "], "link": ["/docs/en/about.html"]},n{"title": [" Become an Editor "], "desc": [" ", " "], "link": ["/docs/en/help/become.html"]},n{"title": [" Suggest a Site "], "desc": [" ", " "], "link": ["/docs/en/add.html"]},n{"title": [" Help "], "desc": [" ", " "], "link": ["/docs/en/help/helpmain.html"]},n{"title": [" Login "], "desc": [" ", " "], "link": ["/editors/"]},n{"title": [], "desc": [" ", " Share via Facebook "], "link": []},n{"title": [], "desc": [" ", " Share via Twitter "], "link": []},n{"title": [], "desc": [" ", " Share via LinkedIn "], "link": []},n{"title": [], "desc": [" ", " Share via e-Mail "], "link": []},n{"title": [], "desc": [" ", " "], "link": []},n{"title": [], "desc": [" ", " "], "link": []}n]n

第一次運行scrapy的測試成功。

4，接下來的工作

接下來，我將使用GooSeeker API來實現網路爬蟲，省掉對每個item人工去生成和測試xpath的工作量。目前有2個計劃：

1. 在gsExtractor中封裝一個方法：從xslt內容中自動提取每個item的xpath
2. 從gsExtractor的提取結果中自動提取每個item的結果

具體選擇哪個方案，將在接下來的實驗中確定，並發布到gsExtractor新版本中

5，文檔修改歷史

2016-06-11：V1.0，首次發布

上一章 Scrapy入門程序點評 <<<<<首頁>>>>> 下一章 將採集結果從xml格式轉json

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