Scrapy的日志等級

　　

- 在使用scrapy crawl spiderFileName運行程序時，在終端里打印輸出的就是scrapy的日志信息。- 日志信息的種類：ERROR ： 一般錯誤WARNING : 警告INFO : 一般的信息DEBUG ： 調試信息- 設置日志信息指定輸出：在settings.py配置文件中，加入LOG_LEVEL = ‘指定日志信息種類’即可。LOG_FILE = 'log.txt'則表示將日志信息寫入到指定文件中進行存儲。

請求傳參

　　- 在某些情況下，我們爬取的數據不在同一個頁面中，例如，我們爬取一個電影網站，電影的名稱，評分在一級頁面，而要爬取的其他電影詳情在其二級子頁面中。這時我們就需要用到請求傳參。

　　- 案例展示：爬取www.id97.com電影網，將一級頁面中的電影名稱，類型，評分一級二級頁面中的上映時間，導演，片長進行爬取。

爬蟲文件：

import scrapy from moviePro.items import MovieproItemclass MovieSpider(scrapy.Spider):name = 'movie'allowed_domains = ['www.id97.com']start_urls = ['http://www.id97.com/']def parse(self, response):div_list = response.xpath('//div[@class="col-xs-1-5 movie-item"]')for div in div_list:item = MovieproItem()item['name'] = div.xpath('.//h1/a/text()').extract_first()item['score'] = div.xpath('.//h1/em/text()').extract_first()#xpath(string(.))表示提取當前節點下所有子節點中的數據值（.）表示當前節點item['kind'] = div.xpath('.//div[@class="otherinfo"]').xpath('string(.)').extract_first()item['detail_url'] = div.xpath('./div/a/@href').extract_first()#請求二級詳情頁面，解析二級頁面中的相應內容,通過meta參數進行Request的數據傳遞yield scrapy.Request(url=item['detail_url'],callback=self.parse_detail,meta={'item':item})def parse_detail(self,response):#通過response獲取itemitem = response.meta['item']item['actor'] = response.xpath('//div[@class="row"]//table/tr[1]/a/text()').extract_first()item['time'] = response.xpath('//div[@class="row"]//table/tr[7]/td[2]/text()').extract_first()item['long'] = response.xpath('//div[@class="row"]//table/tr[8]/td[2]/text()').extract_first()#提交item到管道yield item

items文件：

# Define here the models for your scraped items # # See documentation in: # https://doc.scrapy.org/en/latest/topics/items.htmlimport scrapyclass MovieproItem(scrapy.Item):# define the fields for your item here like:name = scrapy.Field()score = scrapy.Field()time = scrapy.Field()long = scrapy.Field()actor = scrapy.Field()kind = scrapy.Field()detail_url = scrapy.Field()

管道文件：

# Define your item pipelines here # # Don't forget to add your pipeline to the ITEM_PIPELINES setting # See: https://doc.scrapy.org/en/latest/topics/item-pipeline.htmlimport json class MovieproPipeline(object):def __init__(self):self.fp = open('data.txt','w')def process_item(self, item, spider):dic = dict(item)print(dic)json.dump(dic,self.fp,ensure_ascii=False)return itemdef close_spider(self,spider):self.fp.close()

如何提高scrapy的爬取效率

增加并發：默認scrapy開啟的并發線程為32個，可以適當進行增加。在settings配置文件中修改CONCURRENT_REQUESTS = 100值為100,并發設置成了為100。降低日志級別：在運行scrapy時，會有大量日志信息的輸出，為了減少CPU的使用率?？梢栽O置log輸出信息為INFO或者ERROR即可。在配置文件中編寫：LOG_LEVEL = ‘INFO’禁止cookie：如果不是真的需要cookie，則在scrapy爬取數據時可以進制cookie從而減少CPU的使用率，提升爬取效率。在配置文件中編寫：COOKIES_ENABLED = False禁止重試：對失敗的HTTP進行重新請求（重試）會減慢爬取速度，因此可以禁止重試。在配置文件中編寫：RETRY_ENABLED = False減少下載超時：如果對一個非常慢的鏈接進行爬取，減少下載超時可以能讓卡住的鏈接快速被放棄，從而提升效率。在配置文件中進行編寫：DOWNLOAD_TIMEOUT = 10 超時時間為10s

測試案例：爬取校花網?；▓D片 www.521609.com

import scrapy from xiaohua.items import XiaohuaItemclass XiahuaSpider(scrapy.Spider):name = 'xiaohua'allowed_domains = ['www.521609.com']start_urls = ['http://www.521609.com/daxuemeinv/']pageNum = 1url = 'http://www.521609.com/daxuemeinv/list8%d.html'def parse(self, response):li_list = response.xpath('//div[@class="index_img list_center"]/ul/li')for li in li_list:school = li.xpath('./a/img/@alt').extract_first()img_url = li.xpath('./a/img/@src').extract_first()item = XiaohuaItem()item['school'] = schoolitem['img_url'] = 'http://www.521609.com' + img_urlyield itemif self.pageNum < 10:self.pageNum += 1url = format(self.url % self.pageNum)#print(url)yield scrapy.Request(url=url,callback=self.parse)

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# Define here the models for your scraped items # # See documentation in: # https://doc.scrapy.org/en/latest/topics/items.htmlimport scrapyclass XiaohuaItem(scrapy.Item):# define the fields for your item here like:# name = scrapy.Field()school=scrapy.Field()img_url=scrapy.Field()

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# Define your item pipelines here # # Don't forget to add your pipeline to the ITEM_PIPELINES setting # See: https://doc.scrapy.org/en/latest/topics/item-pipeline.htmlimport json import os import urllib.request class XiaohuaPipeline(object):def __init__(self):self.fp = Nonedef open_spider(self,spider):print('開始爬蟲')self.fp = open('./xiaohua.txt','w')def download_img(self,item):url = item['img_url']fileName = item['school']+'.jpg'if not os.path.exists('./xiaohualib'):os.mkdir('./xiaohualib')filepath = os.path.join('./xiaohualib',fileName)urllib.request.urlretrieve(url,filepath)print(fileName+"下載成功")def process_item(self, item, spider):obj = dict(item)json_str = json.dumps(obj,ensure_ascii=False)self.fp.write(json_str+'\n')#下載圖片 self.download_img(item)return itemdef close_spider(self,spider):print('結束爬蟲')self.fp.close()

配置文件：

USER_AGENT = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36'# Obey robots.txt rules ROBOTSTXT_OBEY = False# Configure maximum concurrent requests performed by Scrapy (default: 16) CONCURRENT_REQUESTS = 100 COOKIES_ENABLED = False LOG_LEVEL = 'ERROR' RETRY_ENABLED = False DOWNLOAD_TIMEOUT = 3 # Configure a delay for requests for the same website (default: 0) # See https://doc.scrapy.org/en/latest/topics/settings.html#download-delay # See also autothrottle settings and docs # The download delay setting will honor only one of: #CONCURRENT_REQUESTS_PER_DOMAIN = 16 #CONCURRENT_REQUESTS_PER_IP = 16 DOWNLOAD_DELAY = 3

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轉載于:https://www.cnblogs.com/wanglan/p/10826999.html

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