网络爬虫基础练习
0.可以新建一个用于练习的html文件,在浏览器中打开。
1.利用requests.get(url)获取网页页面的html文件
import requests
newsurl='http://news.gzcc.cn/html/xiaoyuanxinwen/'
res = requests.get(newsurl) #返回response对象
res.encoding='utf-8'
2.利用BeautifulSoup的HTML解析器,生成结构树
from bs4 import BeautifulSoup
soup = BeautifulSoup(res.text,'html.parser')
3.找出特定标签的html元素
soup.p #标签名,返回第一个
soup.head
soup.p.name #字符串
soup.p. attrs #字典,标签的所有属性
soup.p. contents # 列表,所有子标签
soup.p.text #字符串
soup.p.string
soup.select(‘li')
4.取得含有特定CSS属性的元素
soup.select('#p1Node')
soup.select('.news-list-title')
5.练习:
1.取出h1标签的文本
1 # -*- coding: UTF-8 -*- 2 import bs4 3 import requests 4 '''获取网页内容 以HTML结构显示''' 5 news_url = 'http://localhost:63342/ClassTest2/2018_3_29/0230.html?_ijt=nq55lct9kip059122aq7p7ph3l' 6 res = requests.get(news_url) 7 res.encoding = 'utf-9' 8 '''print(res.text)''' 9 10 '''利用 BeautifulSoup的HTML解析器,生成结构树''' 11 from bs4 import BeautifulSoup 12 soup = BeautifulSoup(res.text,'html.parser') 13 print(soup.h1.contents)
2.取出a标签的链接
1 # -*- coding: UTF-8 -*- 2 import bs4 3 import requests 4 '''获取网页内容 以HTML结构显示''' 5 news_url = 'http://localhost:63342/ClassTest2/2018_3_29/0230.html?_ijt=ohp3e6obh3558bpqifnnv6u662' 6 res = requests.get(news_url) 7 res.encoding = 'utf-9' 8 '''print(res.text)''' 9 10 '''利用 BeautifulSoup的HTML解析器,生成结构树''' 11 from bs4 import BeautifulSoup 12 soup = BeautifulSoup(res.text,'html.parser') 13 print(soup.a.text)
3.取出所有li标签的所有内容
# -*- coding: UTF-8 -*- import bs4 import requests '''获取网页内容 以HTML结构显示''' news_url = 'http://localhost:63342/ClassTest2/2018_3_29/0230.html?_ijt=4sg5kmvqudlghcg08lhi7dl2ok' res = requests.get(news_url) res.encoding = 'utf-9' '''print(res.text)''' '''利用 BeautifulSoup的HTML解析器,生成结构树''' from bs4 import BeautifulSoup soup = BeautifulSoup(res.text,'html.parser') soup_list = soup.select('li') for i in range(soup_list.__len__()): print(soup_list[i].text)
4.取出一条新闻的标题、链接、发布时间、来源
标题:
print(soup.select('li')[0].select('.news-list-title')[0].text)
链接:
print(soup.select('li')[0].a.attrs['href'])
发布时间:
print(soup.select('li')[0].select('.news-list-info')[0].contents[0].text)
来源:
print(soup.select('li')[0].select('.news-list-info')[0].contents[1].text)