“阳光高考爬虫项目揭秘：增量爬虫与断点续抓的Python实战“

阳光高考项目

项目要求

爬取各大高校基本信息和招生简章（招生简章要求存储为pdf格式并且入库）

数据库表设计

id
task_url
status：0(未抓取)，1(抓取中)，2(抓取完毕)，3(错误)，4(更新中)，5(数据更新成功)，6(数据未更新，保持原样)，9(暂无)，8(暂无)
- 3：错误，是因为此div下根本没p标签，所以根本等不到导致超时错误await page.waitForXPath(‘//div[@class=“content zszc-content UEditor”]//p’)，可以单独处理，总共4个
- 特殊的能等待到的，有的是多个p标签、有的是多个div标签、有的是表格，都已经做了单独的处理
university_name
competent_department
educational_background
title
contents

阳光简章1

由于两次页面跳转，会将之前的page对象销毁，无法进行item的循环爬取，所以应先根据item循环抓取task_url和必要数据入库

后续再读取task_url进行爬取

源码:

python">import asyncio  # 协程
from pyppeteer import launch
from pyppeteer_stealth import stealth  # 消除指纹
from lxml import etree  # xpath解析数据
import pymysqlwidth, height = 1366, 768  # 设置浏览器宽度和高度conn = pymysql.connect(user='root', password='123456', db='sunshine')
cursor = conn.cursor()async def main():# 设置启动时是否开启浏览器可视，消除控制条信息browser = await launch(headless=False, args=['--disable-infobars'])  # 设置浏览器和添加属性# 开启一个页面对象page = await browser.newPage()# 设置浏览器宽高await page.setViewport({'width': width, 'height': height})# 消除指纹await stealth(page)  # <-- Here# 设置浏览器宽高await page.setViewport({'width': width, 'height': height})# 访问第一页await page.goto('https://gaokao.chsi.com.cn/zsgs/zhangcheng/listVerifedZszc--method-index,ssdm-,yxls-,xlcc-,zgsx-,yxjbz-,start-0.dhtml')await page.waitForXPath('//li[@class="ivu-page-item"]/@title')  # 根据xpaath来等待某个节点出现# 获取最大页max_page_1 = await page.xpath('//li[@class="ivu-page-item"]/@title')max_page = await (await max_page_1[-1].getProperty("textContent")).jsonValue()# print(max_page)for pp in range(int(max_page)):print(pp*100)await page.goto('https://gaokao.chsi.com.cn/zsgs/zhangcheng/listVerifedZszc--method-index,ssdm-,yxls-,xlcc-,zgsx-,yxjbz-,start-{}.dhtml'.format(pp*100))# 爬取单页数据await asyncio.sleep(2)# 等待元素出现 根据CSS选择器的语法等待某个节点出现，跟pyquery语法差不多await page.waitForSelector('div.info-box')# 拉滚动条# arg1: 文档向右滚动的像素数 arg2: 文档向下滚动的像素数await page.evaluate('window.scrollBy(200, document.body.scrollHeight)')# 等待最后一个商品出现await asyncio.sleep(2)# 解析单页数据div_list = await page.xpath('//div[@class="info-box"]')for i in div_list:university_name_1 = await i.xpath('div[1]/a')competent_department_1 = await i.xpath('a[1]')educational_background_1 = await i.xpath('a[2]')# 大学名称university_name = await (await university_name_1[0].getProperty("textContent")).jsonValue()# 接管部门competent_department = await (await competent_department_1[0].getProperty("textContent")).jsonValue()# 教育背景educational_background = await (await educational_background_1[0].getProperty("textContent")).jsonValue()educational_background = educational_background.replace('\n', '')educational_background = educational_background.replace(' ', '')# 简章url# zszc-link text-decoration-none no-info# zszc-link text-decoration-nonetask_url_1 = await i.xpath('a[@class=\"zszc-link text-decoration-none\" and not(contains(@class, \"no-info\"))]/@href')if len(task_url_1) > 0:task_url = await (await task_url_1[0].getProperty("textContent")).jsonValue()task_url = "https://gaokao.chsi.com.cn{}".format(task_url)sql = 'insert into tasks(task_url,status,university_name,competent_department,educational_background)' \' values(\"{}\", \"0\", \"{}\", \"{}\", \"{}\")'.format(task_url.strip(), university_name.strip(),competent_department.strip(), educational_background.strip())else:task_url = "暂无"sql = 'insert into tasks(task_url,status,university_name,competent_department,educational_background)' \' values(\"{}\", \"9\", \"{}\", \"{}\", \"{}\")'.format(task_url.strip(), university_name.strip(),competent_department.strip(), educational_background.strip())# strip去空格: xpath获取到的数据左右可能有空格, 占用数据库空间# print(1, university_name.strip(), 2, conpetent_department.strip(), 3, educational_background.strip(), 4,#       task_url.strip())# print(sql)cursor.execute(sql)conn.commit()await asyncio.sleep(100)if __name__ == '__main__':asyncio.get_event_loop().run_until_complete(main())

阳光简章2

源码：

python">import asyncio  # 协程
import multiprocessing
import timefrom pyppeteer import launch
from pyppeteer_stealth import stealth  # 消除指纹
from lxml import etree  # xpath解析数据
import pymysql
from pymysql.converters import escape_string
import oswidth, height = 1366, 768  # 设置浏览器宽度和高度r = redis.Redis(host="127.0.0.1", port=6379, db=1)MAX_RETRIES = 3# 章节页面保存成pdf或者word 并存入数据库
# 多进程或者多协程提高抓取速度
# 断点续抓
# 增量爬虫async def main():conn = pymysql.connect(user='root', password='123456', db='sunshine')cursor = conn.cursor()# 设置启动时是否开启浏览器可视，消除控制条信息global retriesbrowser = await launch(headless=True, args=['--disable-infobars'])  # 设置浏览器和添加属性# 开启一个页面对象page = await browser.newPage()# 设置浏览器宽高await page.setViewport({'width': width, 'height': height})# 消除指纹await stealth(page)  # <-- Here# 设置浏览器宽高await page.setViewport({'width': width, 'height': height})# 访问某个页面allline = get_count()for i in range(allline):retries = 0  # 重置重试次数result = get_task()url = result[1]id = result[0]while retries < MAX_RETRIES:await page.goto(url)# 智能等待: 不能百分百确定一定有这个链接, 所以错误处理try:await page.waitForXPath('//a[@class="zszc-zc-title"]/@href')except:sql = 'update tasks set status=\"8\" where id = {}'.format(id)cursor.execute(sql)conn.commit()continue# info_urlinfo_url_1 = await page.xpath('//a[@class="zszc-zc-title"]/@href')info_url = await (await info_url_1[0].getProperty("textContent")).jsonValue()info_url = "https://gaokao.chsi.com.cn{}".format(info_url)# 访问info_urlawait page.goto(info_url)# 智能等待try:await page.waitForXPath('//div[@class="content zszc-content UEditor"]//p')except Exception:retries += 1await asyncio.sleep(1)continue# titletitle = await page.xpath('//h2[@class="zszc-content-title"]')title = await (await title[0].getProperty("textContent")).jsonValue()# 截图成为pdf# 目前只支持无头模式的有头的不行if not os.path.isdir('阳光/pdf'):os.makedirs('阳光/pdf')await page.pdf({'path': '阳光/pdf/{}.pdf'.format(title), 'format': 'a4'})# contentscontents_p = await page.xpath('//div[@class="content zszc-content UEditor"]//p')contents_list = '\n'.join([await (await x.getProperty("textContent")).jsonValue() for x in contents_p])# 处理表格等特殊情况if not contents_list.strip():# content_div = await page.xpath('//table')[0].xpath('string(.)')# content_list = await (await content_div[0].getProperty("textContent")).jsonValue()# print(55555,content_list)try:content = etree.HTML(await page.content()).xpath('//table')[0]contents = escape_string(etree.tostring(content, encoding='utf-8').decode())except IndexError:passtry:contents_div = await page.xpath('//div[@class="content zszc-content UEditor"]//div')contents_list = '\n'.join([await (await x.getProperty("textContent")).jsonValue() for x in contents_div])contents = escape_string(contents_list)except Exception:pass# print(555555, content_list)else:# escape_string: 对文本中单双引号进行转义, 防止单双引号冲突contents = escape_string(contents_list)# print(title, contents_list)print(title)# 入库sql = 'update tasks set title=\"{}\", contents=\"{}\", status=\"2\" where id={}'.format(title, contents, id)cursor.execute(sql)conn.commit()breakif retries == 3:sql = 'update tasks set status=\"3\" where id={}'.format(id)cursor.execute(sql)conn.commit()# 关闭浏览器await browser.close()# 获取任务数目
def get_count():conn = pymysql.connect(user='root', password='123456', db='sunshine')cursor = conn.cursor()sql = 'select count(*) from tasks where status=\"0\"'cursor.execute(sql)result = cursor.fetchone()print(result)return result[0]# 获取一个任务
def get_task():conn = pymysql.connect(user='root', password='123456', db='sunshine')cursor = conn.cursor()sql = 'select * from tasks where status=\"0\"'cursor.execute(sql)result = cursor.fetchone()sql1 = 'update tasks set status=\"1\" where id={}'.format(result[0])cursor.execute(sql1)conn.commit()return result# 仅基于异步运行
def run_async():asyncio.get_event_loop().run_until_complete(main())# 多进程运行
def run_mutiprocess():pool = multiprocessing.Pool(8)for _ in range(8):# multiprocessing.Pool 是为同步函数设计的, 如果必须使用 multiprocessing，确保每个进程内有自己的事件循环。pool.apply_async(run_async)print('Waiting for all subprocesses done...')pool.close()pool.join()print('All subprocesses done.')async def run_gather():tasks = [main() for _ in range(8)]await asyncio.gather(*tasks)# 多协程运行
def run_coroutine():asyncio.get_event_loop().run_until_complete(run_gather())if __name__ == '__main__':start_time = time.time()# 仅基于异步# run_async()# 多进程run_mutiprocess()# 多协程# run_coroutine()end_time = time.time()print("总共耗时: {}".format(end_time - start_time))

多进程

33 min

多协程

项目亮点

上面项目的面试点

status字段有1的必要性

多进程共享资源的问题:
如果没有1，则多进程爬取数据时存在多个进程抢占同一个资源的情况，而程序在爬取此task_url时将status字段设置为1则避免了这种情况的发生

异常处理

一般出现在智能等待(超时错误导致的一系列错误)，设立重试机制，达到最大重试次数，将status字段设置为0，后续会重新进行抓取，防止异常发生导致程序终止

完善上面项目

断点续抓

人为中断程序，下次再此运行程序抓取数据能够保证继续抓取

python"># 完善项目: 断点续抓
async def crawler_resumpt():conn = pymysql.connect(user='root', password='123456', db='sunshine')cursor = conn.cursor()sql = 'select * from tasks where status=\"1\" or status=\"0\" order by id'cursor.execute(sql)results = cursor.fetchall()# 设置启动时是否开启浏览器可视，消除控制条信息global retriesbrowser = await launch(headless=True, args=['--disable-infobars'])  # 设置浏览器和添加属性# 开启一个页面对象page = await browser.newPage()# 设置浏览器宽高await page.setViewport({'width': width, 'height': height})# 消除指纹await stealth(page)  # <-- Here# 设置浏览器宽高await page.setViewport({'width': width, 'height': height})for result in results:# 访问某个页面retries = 0  # 重置重试次数url = result[1]id = result[0]while retries < MAX_RETRIES:await page.goto(url)# 智能等待: 不能百分百确定一定有这个链接, 所以错误处理try:await page.waitForXPath('//a[@class="zszc-zc-title"]/@href')except:sql = 'update tasks set status=\"8\" where id = {}'.format(id)cursor.execute(sql)conn.commit()continue# info_urlinfo_url_1 = await page.xpath('//a[@class="zszc-zc-title"]/@href')info_url = await (await info_url_1[0].getProperty("textContent")).jsonValue()info_url = "https://gaokao.chsi.com.cn{}".format(info_url)# 访问info_urlawait page.goto(info_url)# 智能等待try:await page.waitForXPath('//div[@class="content zszc-content UEditor"]//p')except Exception:retries += 1await asyncio.sleep(1)continue# titletitle = await page.xpath('//h2[@class="zszc-content-title"]')title = await (await title[0].getProperty("textContent")).jsonValue()# 截图成为pdf# 目前只支持无头模式的有头的不行if not os.path.isdir('阳光/pdf'):os.makedirs('阳光/pdf')await page.pdf({'path': '阳光/pdf/{}.pdf'.format(title), 'format': 'a4'})# contentscontents_p = await page.xpath('//div[@class="content zszc-content UEditor"]//p')contents_list = '\n'.join([await (await x.getProperty("textContent")).jsonValue() for x in contents_p])# 处理表格特殊情况if not contents_list.strip():# content_div = await page.xpath('//table')[0].xpath('string(.)')# content_list = await (await content_div[0].getProperty("textContent")).jsonValue()# print(55555,content_list)content = etree.HTML(await page.content()).xpath('//table')[0]contents = escape_string(etree.tostring(content, encoding='utf-8').decode())# print(555555, content_list)else:# escape_string: 对文本中单双引号进行转义, 防止单双引号冲突contents = escape_string(contents_list)# print(title, contents_list)print(title)# 入库sql = 'update tasks set title=\"{}\", contents=\"{}\", status=\"2\" where id={}'.format(title, contents,id)cursor.execute(sql)conn.commit()breakif retries == 3:sql = 'update tasks set status=\"0\" where id={}'.format(id)cursor.execute(sql)conn.commit()# 关闭浏览器await browser.close()

增量爬虫，指纹去重

指纹：将抓取数据拼接成字符串，并通过md5或sha1加密形成的密钥字符串即为指纹

将指纹和id存储在redis数据库的无序集合中

后续抓取数据时，构造密钥字符串，根据是否含有此密钥字符串进行去重，若有，则放弃数据更新，若无，则根据id进行数据更新

初始爬虫源码:

python"># 入库
sql = 'update tasks set title=\"{}\", contents=\"{}\", status=\"2\" where id={}'.format(title, contents, id)
cursor.execute(sql)
conn.commit()
# 指纹入库
data = title + contents
r.sadd("sunshine:key", encryption(data))

增量爬虫源码:

python">import asyncio  # 协程
import multiprocessing
import timefrom pyppeteer import launch
from pyppeteer_stealth import stealth  # 消除指纹
from lxml import etree  # xpath解析数据
import pymysql
from pymysql.converters import escape_string
import os
import redis
import hashlibwidth, height = 1366, 768  # 设置浏览器宽度和高度r = redis.Redis(host="127.0.0.1", port=6379, db=1)MAX_RETRIES = 3async def main():conn = pymysql.connect(user='root', password='123456', db='sunshine2')cursor = conn.cursor()# 设置启动时是否开启浏览器可视，消除控制条信息global retries, contentsbrowser = await launch(headless=True, args=['--disable-infobars'])  # 设置浏览器和添加属性# 开启一个页面对象page = await browser.newPage()# 设置浏览器宽高await page.setViewport({'width': width, 'height': height})# 消除指纹await stealth(page)  # <-- Here# 设置浏览器宽高await page.setViewport({'width': width, 'height': height})# 访问某个页面allline = get_count()for i in range(allline):retries = 0  # 重置重试次数result = get_finished_task()url = result[1]id = result[0]while retries < MAX_RETRIES:await page.goto(url)# 智能等待: 不能百分百确定一定有这个链接, 所以错误处理try:await page.waitForXPath('//a[@class="zszc-zc-title"]/@href')except:sql = 'update tasks set status=\"8\" where id = {}'.format(id)cursor.execute(sql)conn.commit()continue# info_urlinfo_url_1 = await page.xpath('//a[@class="zszc-zc-title"]/@href')info_url = await (await info_url_1[0].getProperty("textContent")).jsonValue()info_url = "https://gaokao.chsi.com.cn{}".format(info_url)# 访问info_urlawait page.goto(info_url)# 智能等待try:await page.waitForXPath('//div[@class="content zszc-content UEditor"]//p')except Exception:retries += 1await asyncio.sleep(1)continue# titletitle = await page.xpath('//h2[@class="zszc-content-title"]')title = await (await title[0].getProperty("textContent")).jsonValue()# 截图成为pdf# 目前只支持无头模式的有头的不行if not os.path.isdir('阳光/pdf'):os.makedirs('阳光/pdf')await page.pdf({'path': '阳光/pdf/{}.pdf'.format(title), 'format': 'a4'})# contentscontents_p = await page.xpath('//div[@class="content zszc-content UEditor"]//p')contents_list = '\n'.join([await (await x.getProperty("textContent")).jsonValue() for x in contents_p])# 处理表格等特殊情况if not contents_list.strip():# content_div = await page.xpath('//table')[0].xpath('string(.)')# content_list = await (await content_div[0].getProperty("textContent")).jsonValue()# print(55555,content_list)try:content = etree.HTML(await page.content()).xpath('//table')[0]contents = escape_string(etree.tostring(content, encoding='utf-8').decode())except IndexError:passtry:contents_div = await page.xpath('//div[@class="content zszc-content UEditor"]//div')contents_list = '\n'.join([await (await x.getProperty("textContent")).jsonValue() for x in contents_div])contents = escape_string(contents_list)except Exception:pass# print(555555, content_list)else:# escape_string: 对文本中单双引号进行转义, 防止单双引号冲突contents = escape_string(contents_list)# print(title, contents_list)print(title)# 入库data = title + contentsif not is_crawlered(data):print("数据更新...")sql = 'update tasks set title=\"{}\", contents=\"{}\", status=\"5\" where id={}'.format(title, contents,id)cursor.execute(sql)conn.commit()else:print("数据已爬取过...")sql = 'update tasks set status=\"6\" where id={}'.format(id)cursor.execute(sql)conn.commit()breakif retries == 3:sql = 'update tasks set status=\"3\" where id={}'.format(id)cursor.execute(sql)conn.commit()# 关闭浏览器await browser.close()# 获取任务数目
def get_count():conn = pymysql.connect(user='root', password='123456', db='sunshine2')cursor = conn.cursor()sql = 'select count(*) from tasks where status=\"2\"'cursor.execute(sql)result = cursor.fetchone()print(result)return result[0]# md5加密
def encryption(data):md5 = hashlib.md5()md5.update(data.encode("utf-8"))return md5.hexdigest()# 获取一个已完成的任务
def get_finished_task():conn = pymysql.connect(user='root', password='123456', db='sunshine2')cursor = conn.cursor()sql = 'select * from tasks where status=\"2\"'cursor.execute(sql)result = cursor.fetchone()sql1 = 'update tasks set status=\"4\" where id={}'.format(result[0])cursor.execute(sql1)conn.commit()return result# 去重
def is_crawlered(data):res = r.sadd("sunshine:key", encryption(data))return res == 0# 仅基于异步运行
def run_async():asyncio.get_event_loop().run_until_complete(main())# 多进程运行
def run_mutiprocess():pool = multiprocessing.Pool(8)for _ in range(8):# multiprocessing.Pool 是为同步函数设计的, 如果必须使用 multiprocessing，确保每个进程内有自己的事件循环。pool.apply_async(run_async)print('Waiting for all subprocesses done...')pool.close()pool.join()print('All subprocesses done.')async def run_gather():tasks = [main() for _ in range(4)]await asyncio.gather(*tasks)# 多协程运行
def run_coroutine():asyncio.get_event_loop().run_until_complete(run_gather())if __name__ == '__main__':start_time = time.time()# 仅基于异步# run_async()# 多进程run_mutiprocess()# 多协程# run_coroutine()end_time = time.time()print("总共耗时: {}".format(end_time - start_time))