编程学习网站题目爬取

1.访问菜鸟教程（https://www.runoob.com），爬取其Python3实例模块的题目内容，要求输出格式如下图所示。

import requests
from lxml import etree
import time

# 获取题目链接
url = 'https://www.runoob.com/python3/python3-examples.html'
web_data = requests.get(url)   
dom = etree.HTML(web_data.text, etree.HTMLParser(encoding='utf-8'))  # 网页解析
exerciseList= dom.xpath('//div[@id="content"]/ul/li/a/text()')       # 练习题名称
urlList= dom.xpath('//div[@id="content"]/ul/li/a/@href')             # 练习题超链接
urlList = ['/python3/'+i  if '/python3/' not in i else i for i in urlList ]                               
urlList = ['https://www.runoob.com' + i if 'www.runoob.com/' not in i else 'https:'+i for i in urlList]   

exerciseString = 'n'.join(exerciseList)      # 将练习题名称拼接成一个字符串
with open('exercisePython.txt', 'w') as f:
    f.write(exerciseString)
#爬取题目数据及整理写出
resultList = []
for url in urlList:
    web_data = requests.get(url)
    dom = etree.HTML(web_data.text, etree.HTMLParser(encoding='utf-8'))  # 网页源码解析
    # 获取题目及答案
    title = dom.xpath('string(//div[@id="content"]/h1)')       # 练习题名称
    content = dom.xpath('string(//div[@id="content"]/p[2])')   # 练习题描述内容
    code = dom.xpath('string(//div[@id="content"]//div[@]//div[@])')  # 练习题答案
    result = dom.xpath('string(//div[@id="content"]/p[3])')    # 结果描述
    output = dom.xpath('string(//div[@id="content"]/pre)')     # 目标输出
    res = title + 'n' + content+ 'n'   # 将内容进行拼接
    resultList.append(res)
    time.sleep(1)
    print(url, 'n', res)
mid = resultList.copy()
for i in range(len(mid)):
    mid[i] = str(i+1)+'、'+ mid[i]  # 加入题目序号
with open('Python编程基础上机题库1.txt', 'w', encoding='utf-8') as f:
    f.write('n'.join(mid))         # 将数据写出

import requests
from lxml import etree
headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36'
        }
li_list = []
url='https://www.runoob.com/python3/python3-examples.html'
resp=requests.get(url=url).text
tree=etree.HTML(resp)
url_list=tree.xpath('//*[@id="content"]/ul/li/a/@href')  #链接
for li in url_list:
    if 'www' not in li:
        li_list.append('https://www.runoob.com/python3/'+li)
    else:li_list.append('https:'+li)
count=1
for urls in li_list:
    count+=1
    nextPage= requests.get(url=urls,headers=headers).text
    tree2=etree.HTML(nextPage)
    title=tree2.xpath('normalize-space(//*[@id="content"]/h1/text())')
    contents = tree2.xpath('normalize-space(//*[@id="content"]/p[2]/text())')
    result=str(count)+'、'+str(title)+'n'+str(contents).lstrip()
    print(result)