12. Scrapy框架使用Selenium

• 案例目标：

  • 本节案例主要是通过Scrapy框架使用Selenium，以PhantomJS进行演示，爬取淘宝商品信息案例，并将信息存入数据库MongoDB中。

• 准备工作：

  • 请确保PhantomJS和MongoDB都已安装号，并确保可以正常运行，安装好Scrapy、Selenium和PyMongod库。

① 创建项目

• 首先新建项目，名为scrapyseleniumtest：

scrapy startproject scrapyseleniumtest

• 进入项目目录下，创建一个Spider（爬虫类）：

cd srapytseleniumtest
scrapy genspider taobao www.baobao.com

• 进入settings.py的配置文件：将ROBOTSTXT_OBEY改为false

ROBOTSTXT_OBEY = False

② 定义Item类

# 定义信息封装类（图片、价格、购买人数、标题、店铺、发货源）
from scrapy import Item, Field

class ProductItem(Item):

    collection = 'products'

    image = Field()
    price = Field()
    deal = Field()
    title = Field()
    shop = Field()
    location = Field()

③ 解析页面

• 在配置文件settings.py最后面定义搜索关键字和最大页码数信息：

KEYWORDS = ['iPad']

MAX_PAGE = 100

• 进入spider/taobao.py文件中编写，代码如下：

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

    def parse(self, response):
        pass

④ 对接Selenium

• 通过定义DownloaderMiddleware中间件来实现对Selenium的使用。

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

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抓取页面
        :param request: Request对象
        :param spider: Spider对象
        :return: HtmlResponse
        """
        self.logger.debug('PhantomJS is Starting')
        page = request.meta.get('page', 1)
        try:
            self.browser.get(request.url)
            if page > 1:
                input = self.wait.until(
                    EC.presence_of_element_located((By.CSS_SELECTOR, '#mainsrp-pager div.form > input')))
                submit = self.wait.until(
                    EC.element_to_be_clickable((By.CSS_SELECTOR, '#mainsrp-pager div.form > span.btn.J_Submit')))
                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)))
            self.wait.until(EC.presence_of_element_located((By.CSS_SELECTOR, '.m-itemlist .items .item')))
            return HtmlResponse(url=request.url, body=self.browser.page_source, request=request, encoding='utf-8',
                                status=200)
        except TimeoutException:
            return HtmlResponse(url=request.url, status=500, request=request)

    @classmethod
    def from_crawler(cls, crawler):
        return cls(timeout=crawler.settings.get('SELENIUM_TIMEOUT'),
                   service_args=crawler.settings.get('PHANTOMJS_SERVICE_ARGS'))

• 在settings.py配置文件中.设置我们自定义的中间件设置：

DOWNLOADER_MIDDLEWARES = {
    'scrapyseleniumtest.middlewares.SeleniumMiddleware': 543,
}

⑤ 解析页面信息

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

    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

⑥ 存储结果

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()

• 配置文件信息：

ITEM_PIPELINES = {
    'scrapyseleniumtest.pipelines.MongoPipeline': 300,
}


KEYWORDS = ['iPad']

MAX_PAGE = 100

SELENIUM_TIMEOUT = 20

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

MONGO_URI = 'localhost'

MONGO_DB = 'taobao'