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python - Scrapy + selenium 为每个 url 请求两次

问题描述

import scrapy 
from selenium import webdriver

class ProductSpider(scrapy.Spider):
    name = "product_spider"
    allowed_domains = ['ebay.com']
    start_urls = ['http://www.ebay.com/sch/i.html?_odkw=books&_osacat=0&_trksid=p2045573.m570.l1313.TR0.TRC0.Xpython&_nkw=python&_sacat=0&_from=R40']

    def __init__(self):
        self.driver = webdriver.Firefox()

    def parse(self, response):
        self.driver.get(response.url)

        while True:
            next = self.driver.find_element_by_xpath('//td[@class="pagn-next"]/a')

            try:
                next.click()

                # get the data and write it to scrapy items
            except:
                break

        self.driver.close()

带有scrapy的硒用于动态页面

此解决方案效果很好，但它两次请求相同的 url，一次由 scrapy 调度程序请求，另一次由 selenium web 驱动程序请求。

与没有硒的scrapy请求相比，完成这项工作需要两倍的时间。如何避免这种情况？

标签： pythonseleniumweb-scrapingscrapy

解决方案

这是一个可以用来解决这个问题的技巧。

为 selenium创建一个 Web 服务，在本地运行它

from flask import Flask, request, make_response
from flask_restful import Resource, Api
from selenium import webdriver
from selenium.webdriver.chrome.options import Options

app = Flask(__name__)
api = Api(app)

class Selenium(Resource):
    _driver = None

    @staticmethod
    def getDriver():
        if not Selenium._driver:
            chrome_options = Options()
            chrome_options.add_argument("--headless")

            Selenium._driver = webdriver.Chrome(chrome_options=chrome_options)
        return Selenium._driver

    @property
    def driver(self):
        return Selenium.getDriver()

    def get(self):
        url = str(request.args['url'])

        self.driver.get(url)

        return make_response(self.driver.page_source)

api.add_resource(Selenium, '/')

if __name__ == '__main__':
    app.run(debug=True)

现在http://127.0.0.1:5000/?url=https://stackoverflow.com/users/5939254/yash-pokar将使用 selenium Chrome/Firefox 驱动程序返回已编译的网页。

现在我们的蜘蛛会是什么样子，

import scrapy
import urllib


class ProductSpider(scrapy.Spider):
    name = 'products'
    allowed_domains = ['ebay.com']
    urls = [
        'http://www.ebay.com/sch/i.html?_odkw=books&_osacat=0&_trksid=p2045573.m570.l1313.TR0.TRC0.Xpython&_nkw=python&_sacat=0&_from=R40',
    ]

    def start_requests(self):
        for url in self.urls:
            url = 'http://127.0.0.1:5000/?url={}'.format(urllib.quote(url))
            yield scrapy.Request(url)

    def parse(self, response):
        yield {
            'field': response.xpath('//td[@class="pagn-next"]/a'),
        }

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