Python爬虫必备技巧详细总结

自定义函数

import requests
from bs4 import beautifulsoup
headers={'user-agent':'mozilla/5.0 (windows nt 10.0; win64; x64; rv:93.0) gecko/20100101 firefox/93.0'}
def baidu(company):
    url = 'https://www.baidu.com/s?rtt=4&tn=news&word=' + company
    print(url)
    html = requests.get(url, headers=headers).text
    s = beautifulsoup(html, 'html.parser')
    title=s.select('.news-title_1yti1 a')
    for i in title:
        print(i.text)
# 批量调用函数
companies = ['腾讯', '阿里巴巴', '百度集团']
for i in companies:
    baidu(i)

批量输出多个搜索结果的标题

结果保存为文本文件

import requests
from bs4 import beautifulsoup
headers={'user-agent':'mozilla/5.0 (windows nt 10.0; win64; x64; rv:93.0) gecko/20100101 firefox/93.0'}
def baidu(company):
    url = 'https://www.baidu.com/s?rtt=4&tn=news&word=' + company
    print(url)
    html = requests.get(url, headers=headers).text
    s = beautifulsoup(html, 'html.parser')
    title=s.select('.news-title_1yti1 a')
    fl=open('test.text','a', encoding='utf-8')
    for i in title:
        fl.write(i.text + '\n')
# 批量调用函数
companies = ['腾讯', '阿里巴巴', '百度集团']
for i in companies:
    baidu(i)

写入代码

fl=open('test.text','a', encoding='utf-8')
for i in title:
	fl.write(i.text + '\n')

异常处理

for i in companies:
    try:
        baidu(i)
        print('运行成功')
    except:
        print('运行失败')

写在循环中 不会让程序停止运行 而会输出运行失败

休眠时间

import time
for i in companies:
    try:
        baidu(i)
        print('运行成功')
    except:
        print('运行失败')
time.sleep(5)

time.sleep(5)

括号里的单位是秒

放在什么位置 则在什么位置休眠（暂停）

爬取多页内容

百度搜索腾讯

切换到第二页

去掉多多余的

https://www.baidu.com/s?wd=腾讯&pn=10

分析出

https://www.baidu.com/s?wd=腾讯&pn=0 为第一页
https://www.baidu.com/s?wd=腾讯&pn=10 为第二页
https://www.baidu.com/s?wd=腾讯&pn=20 为第三页
https://www.baidu.com/s?wd=腾讯&pn=30 为第四页
……….

代码

from bs4 import beautifulsoup
import time
headers={'user-agent':'mozilla/5.0 (windows nt 10.0; win64; x64; rv:93.0) gecko/20100101 firefox/93.0'}
def baidu(c):
    url = 'https://www.baidu.com/s?wd=腾讯&pn=' + str(c)+'0'
    print(url)
    html = requests.get(url, headers=headers).text
    s = beautifulsoup(html, 'html.parser')
    title=s.select('.t a')
    for i in title:
        print(i.text)

for i in range(10):
    baidu(i)
    time.sleep(2)

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