N0.18——Scrapy框架對接Selenium實現淘寶商品的爬取功能

在之前寫的NO.8文章中介紹了應用Selenium模擬瀏覽器的操作實現抓取JavaScript動態渲染的頁面，俗稱可見及可爬。最近在研究Scrapy框架，因此嘗試Scrapy框架對接Selenium實現淘寶的爬取功能。

一、分析網頁

在Elements選項卡下查看網頁源碼，通過頁碼輸入框切換頁碼：

點擊確定按鈕進行提交：

查看第一頁內容：

單個商品概覽：

二、新建項目

scrapy startproject scrapyseleniumtest

新建一個Spider

scrapy genspider taobao www.taobao.com

修改settings.py中的ROBOTSTXT_OBEY = False,即不遵守機器人協議。

三、定義Item對象（可以理解成初始化）

新建名爲ProductItem的對象，建立與MongoDB的鏈接，將提取信息存放在名爲products的Collections集合中。其中包含六個字段。

# -*- coding: utf-8 -*-
      #Items.py
# Define here the models for your scraped items
#
# See documentation in:
# http://doc.scrapy.org/en/latest/topics/items.html

from scrapy import Item, Field


class ProductItem(Item):
    
    collection = 'products'
    
    image = Field()  #圖片鏈接
    price = Field()  #價格
    deal = Field()   #成交量
    title = Field()  #名稱
    shop = Field()   #店鋪
    location = Field()  #店鋪所在地

四、從調度器取出一個個URL鏈接構造出Request請求傳給下載器，下載器把資源下載下來封裝成Response

# -*- coding: utf-8 -*-
       #中間件
from selenium import webdriver
from selenium.common.exceptions import TimeoutException
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from scrapy.http import HtmlResponse
from logging import getLogger


class SeleniumMiddleware():
    def __init__(self, timeout=None, service_args=[]):
        self.logger = getLogger(__name__)
        self.timeout = timeout
        self.browser = webdriver.PhantomJS(service_args=service_args)
        self.browser.set_window_size(1400, 700)
        self.browser.set_page_load_timeout(self.timeout)
        self.wait = WebDriverWait(self.browser, self.timeout)
    
    def __del__(self):
        self.browser.close()
    
    def process_request(self, request, spider):
        """
            用PhantomJS抓取頁面
            :param request: Request對象
            :param spider: Spider對象
            :return: HtmlResponse
            """
        self.logger.debug('PhantomJS is Starting')
        page = request.meta.get('page', 1)  #通過Request的meta屬性獲取當前需要爬取的頁碼
        try:
            self.browser.get(request.url)  #調用PhantomJS對象的get()方法訪問Request的對應的URL,相當於從Request對象裏獲取請求鏈接，然後再用PhantomJS加載，而不再使用Scrapy裏的Downloader
            if page > 1:
                input = self.wait.until(
                    EC.presence_of_element_located((By.CSS_SELECTOR, '#mainsrp-pager div.form > input')))   #選擇頁碼框
                submit = self.wait.until(
                    EC.element_to_be_clickable((By.CSS_SELECTOR, '#mainsrp-pager div.form > span.btn.J_Submit'))) #確定按鈕
                input.clear()
                input.send_keys(page)
                submit.click()
            self.wait.until(
                EC.text_to_be_present_in_element((By.CSS_SELECTOR, '#mainsrp-pager li.item.active > span'), str(page)))  #第一頁
            self.wait.until(EC.presence_of_element_located((By.CSS_SELECTOR, '.m-itemlist .items .item')))  #單個商品概覽
            return HtmlResponse(url=request.url, body=self.browser.page_source, request=request, encoding='utf-8',
                                                status=200)#調用page_source屬性獲取頁碼的源代碼，用它來直接構造並返回一個HtmlResponse對象，構造這個對象需要傳入url,body等多個參數
        except TimeoutException:
            return HtmlResponse(url=request.url, status=500, request=request) #返回一個HtmlResponse對象。利用PhantomJS代替Scrapy完成頁面的加載，最後將Response返回，回傳給Spider內的回調函數進行解析
    
    @classmethod
    def from_crawler(cls, crawler):
        return cls(timeout=crawler.settings.get('SELENIUM_TIMEOUT'),
                   service_args=crawler.settings.get('PHANTOMJS_SERVICE_ARGS'))

五、設計Spider解析頁面

通過第四步驟直接返回了一個HtmlResponse對象，它是Response的子類，返回之後會迭代調用每個Downloader Middleware的process_response()方法，進而將每個商品信息轉化成HtmlResponse對象回傳給Spider內的回到函數進行解析。

# -*- coding: utf-8 -*-

#回調函數
from scrapy import Request, Spider
from urllib.parse import quote
from scrapyseleniumtest.items import ProductItem


class TaobaoSpider(Spider):
    name = 'taobao'
    allowed_domains = ['www.taobao.com']
    base_url = 'https://s.taobao.com/search?q='
    
    
    def start_requests(self):
        for keyword in self.settings.get('KEYWORDS'):
            for page in range(1, self.settings.get('MAX_PAGE') + 1):
                url = self.base_url + quote(keyword)
                yield Request(url=url, callback=self.parse, meta={'page': page}, dont_filter=True)
#對Downloader Middleware回傳的Response對象進行解析，以下是實現該功能的回調函數
    def parse(self, response):
        products = response.xpath(
                              '//div[@id="mainsrp-itemlist"]//div[@class="items"][1]//div[contains(@class, "item")]')
        for product in products:
            item = ProductItem()
            item['price'] = ''.join(product.xpath('.//div[contains(@class, "price")]//text()').extract()).strip()
            item['title'] = ''.join(product.xpath('.//div[contains(@class, "title")]//text()').extract()).strip()
            item['shop'] = ''.join(product.xpath('.//div[contains(@class, "shop")]//text()').extract()).strip()
            item['image'] = ''.join(product.xpath('.//div[@class="pic"]//img[contains(@class, "img")]/@data-src').extract()).strip()
            item['deal'] = product.xpath('.//div[contains(@class, "deal-cnt")]//text()').extract_first()
            item['location'] = product.xpath('.//div[contains(@class, "location")]//text()').extract_first()
            yield item

六、存儲結果

實現一個 Item Pipeline，將結果保存到MongoDB。

# -*- coding: utf-8 -*-

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: http://doc.scrapy.org/en/latest/topics/item-pipeline.html

#當Spider解析完Response之後，Item會傳遞到Item Pipeline做數據清洗和存儲操作
import pymongo

class MongoPipeline(object):
    def __init__(self, mongo_uri, mongo_db):
        self.mongo_uri = mongo_uri
        self.mongo_db = mongo_db
    
    @classmethod
    def from_crawler(cls, crawler):
        return cls(mongo_uri=crawler.settings.get('MONGO_URI'), mongo_db=crawler.settings.get('MONGO_DB'))
    
    def open_spider(self, spider):
        self.client = pymongo.MongoClient(self.mongo_uri)
        self.db = self.client[self.mongo_db]
    
    def process_item(self, item, spider):
        self.db[item.collection].insert(dict(item))
        return item
    
    def close_spider(self, spider):
        self.client.close()

七、附加settings.py設置

# -*- coding: utf-8 -*-

# Scrapy settings for scrapyseleniumtest project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     http://doc.scrapy.org/en/latest/topics/settings.html
#     http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#     http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'scrapyseleniumtest'

SPIDER_MODULES = ['scrapyseleniumtest.spiders']
NEWSPIDER_MODULE = 'scrapyseleniumtest.spiders'

# Crawl responsibly by identifying yourself (and your website) on the user-agent
# USER_AGENT = 'scrapyseleniumtest (+http://www.yourdomain.com)'

# Obey robots.txt rules
ROBOTSTXT_OBEY = False

# Configure maximum concurrent requests performed by Scrapy (default: 16)
# CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See http://scrapy.readthedocs.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
# DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
# CONCURRENT_REQUESTS_PER_DOMAIN = 16
# CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
# COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
# TELNETCONSOLE_ENABLED = False

# Override the default request headers:
# DEFAULT_REQUEST_HEADERS = {
#   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
#   'Accept-Language': 'en',
# }

# Enable or disable spider middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
# SPIDER_MIDDLEWARES = {
#    'scrapyseleniumtest.middlewares.ScrapyseleniumtestSpiderMiddleware': 543,
# }

# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
DOWNLOADER_MIDDLEWARES = {
    'scrapyseleniumtest.middlewares.SeleniumMiddleware': 543,
}

# Enable or disable extensions
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html
# EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
# }

# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
    'scrapyseleniumtest.pipelines.MongoPipeline': 300,
}

# Enable and configure the AutoThrottle extension (disabled by default)
# See http://doc.scrapy.org/en/latest/topics/autothrottle.html
# AUTOTHROTTLE_ENABLED = True
# The initial download delay
# AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
# AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
# AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
# AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
# HTTPCACHE_ENABLED = True
# HTTPCACHE_EXPIRATION_SECS = 0
# HTTPCACHE_DIR = 'httpcache'
# HTTPCACHE_IGNORE_HTTP_CODES = []
# HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

KEYWORDS = ['coser']

MAX_PAGE = 100

SELENIUM_TIMEOUT = 20

PHANTOMJS_SERVICE_ARGS = ['--load-images=false', '--disk-cache=true']

MONGO_URI = 'localhost'

MONGO_DB = 'taobao'

八、效果展示

命令行進入項目目錄：

scrapy crawl taobao

N0.18——Scrapy框架對接Selenium實現淘寶商品的爬取功能

一、分析網頁

二、新建項目

三、定義Item對象（可以理解成初始化）

四、從調度器取出一個個URL鏈接構造出Request請求傳給下載器，下載器把資源下載下來封裝成Response

五、設計Spider解析頁面

六、存儲結果

七、附加settings.py設置

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