分别用requests和selenium实现了拉勾的爬虫

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因为下周一要去腾讯面试写代码，面试官说会考爬虫和数据处理，我就寻思着写个爬虫练练手，因为最近几天一直都在拉勾上找工作就用拉勾拿来练手了。

OSX 10.14.6 on Macbook pro 2017
Selenium==3.11.0
Python3.64
Chromedriver 70.0.3538.97

https://github.com/supersu097/mycrawler/tree/master/lagou

Request 版本：http://eunsetee.com/EKKQ
Selenium 版本：http://eunsetee.com/EKNx

Request 版本代码是完全照搬原作者的，Selenium 版只参考了点击下一页的两行代码，其它代码 copy 自以前写的爬虫, 具体大家可以进原文章看看，然后对比我下面的代码

# coding = 'utf-8'

from selenium.webdriver.chrome.webdriver import WebDriver as ChromeDriver
from user_agent import generate_user_agent
from os.path import join as os_join
from bs4 import BeautifulSoup
import os
import time
import pandas


class Lagou(object):
    CURR_PATH = os.path.abspath('.')
    CHROME_DRIVER_PATH: str = os_join(CURR_PATH, 'chromedriver_mac')

    def __init__(self, initial_url: str):
        from selenium.webdriver.chrome.options import Options as ChromeOptions
        self.initial_url: str = initial_url
        options: ChromeOptions = ChromeOptions()
        # options.add_argument('headless')
        custom_ua: str = generate_user_agent(os='win')
        options.add_argument('user-agent=' + custom_ua)
        self.driver = ChromeDriver(executable_path=self.CHROME_DRIVER_PATH,
                                   chrome_options=options)

    def get_first_page_source(self):
        try:
            self.driver.implicitly_wait(5)
            self.driver.set_script_timeout(20)
            self.driver.set_page_load_timeout(25)
            self.driver.get(self.initial_url)
            page_source: str = self.driver.page_source
            return page_source
        except KeyboardInterrupt:
            self.driver.quit()
            print('The exception of KeyboardInterrupt'
                  'detected and the chrome driver has quited.')
        except Exception as e:
            print(str(e))
            self.driver.quit()
            exit(1)

    def process_data(self, page_source):
        soup = BeautifulSoup(page_source, 'lxml')
        company_list = soup.select('ul.item_con_list li')
        data_list = []
        for company in company_list:
            attrs = company.attrs
            company_name = attrs['data-company']
            job_name = attrs['data-positionname']
            job_salary = attrs['data-salary']
            data_list.append(company_name + ',' + job_name + ',' + job_salary)
        return data_list

    def get_next_page_source(self):
        try:
            self.driver.implicitly_wait(5)
            self.driver.set_script_timeout(20)
            self.driver.set_page_load_timeout(25)
            next_page = self.driver.find_elements_by_xpath("//span[@class='pager_next ']")
            next_page[0].click()
            page_source: str = self.driver.page_source
            return page_source
        except KeyboardInterrupt:
            self.driver.quit()
            print('The exception of KeyboardInterrupt'
                  'detected and the chrome driver has quited.')
        except Exception as e:
            print(str(e))
            self.driver.quit()
            exit(1)

    @staticmethod
    def save_data(self, data, csv_header):
        table = pandas.DataFrame(data)
        table.to_csv(r'/Users/sharp/Desktop/LaGou.csv', header=csv_header, index=False, mode='a+')

    def save_data_into_csv(self, line_data):
        with open(r'/Users/sharp/Desktop/LaGou.csv', 'a+') as f:
            f.write(line_data+'\n')


url = 'https://www.lagou.com/jobs/list_linux%E8%BF%90%E7%BB%B4?labelWords=&fromSearch=true&suginput='
lagou = Lagou(url)
print('Get page {} source'.format(str(1)))
first_page_source = lagou.get_first_page_source()
first_page_data = lagou.process_data(first_page_source)
lagou.save_data_into_csv('company_name,job_name,job_salary')
for data in first_page_data:
    lagou.save_data_into_csv(data)

for i in range(1, 30):
    print('Get page {} source'.format(str(i+1)))
    next_page_source = lagou.get_next_page_source()
    next_page_data = lagou.process_data(next_page_source)
    for data in first_page_data:
        lagou.save_data_into_csv(data)
    time.sleep(8)

说几个值得注意的地方 – xpath 拿到下一页后要去下标为 0 的第一个元素然后再 click()，代码如下：

next_page = self.driver.find_elements_by_xpath("//span[@class='pager_next ']")
next_page[0].click()

用 headless 模式运行会报 “element is not clickable at point” 错误，所以 options.add_argument('headless')这一行就注释掉了
再一个就是休眠的时间，我第一次爬的时候休眠设置的是 5 秒，结果爬到第 12 页就跳转到了登陆页面，后来我调成了 8 秒，实践证明可以一口气爬完 30 页。
最后要说明的是原博的代码实在读起来比较晦涩，我的呢纯过程式，先处理第一页，然后顺序处理剩余的页面，一目明了，代码更是清晰易懂。

截图中上半部分是 selenium 版本的爬虫生成的，下半部分是 requests 版本的。