python爬虫基础_requests和bs4

这些都是笔记，还缺少详细整理，后续会更新。

下面这种方式,属于入门阶段,手动成分比较多.

首先安装必要组件:

pip3 install requests

pip3 install beautifulsoup4

一、爬汽车之家

#!/usr/bin/env python
# coding:utf-8

import requests
from bs4 import BeautifulSoup

# 1.下载页面
ret = requests.get(url="https://www.autohome.com.cn/news/")
# print(ret) # 得到对象
# ret.encoding="gbk" # 指定编码
# print(ret.apparent_encoding)
ret.encoding = ret.apparent_encoding  # 指定编码等于原始页面编码
# print(ret.text)


# 2. 解析：获取想要的指定内容 beautifulsoup
soup = BeautifulSoup(ret.text, 'html.parser')  # 使用lxml则速度更快

# 如果要加class,则前面加下划线
# div = soup.find(name='div', id='auto-channel-lazyload-article', _class='article-wrapper')  # 找到外部DIV
div = soup.find(name='div', attrs={"id":"auto-channel-lazyload-article","class":"article-wrapper"})  # 使用属性字典方式

li_list = div.find_all(name='li')

for li in li_list:
    h3 = li.find(name='h3')
    if not h3:
        continue
    print(h3.text)

    a = li.find('a')
    # print(a.attrs)
    print(a.get('href'))

    p = li.find(name='p')
    print(p.text)
    print('----->' * 20)

    img = li.find(name='img')
    src = img.get('src')

    filename = src.rsplit('__', maxsplit=1)[1]

    down_img = requests.get(url='https:' + src)
    with open(filename, 'wb') as f:
        f.write(down_img.content)

当然，从for循环输出开始，将内容写入文件或数据库，就随需求了。 

import requests
from bs4 import BeautifulSoup

# 1.下载页面
ret = requests.get(url="https://www.autohome.com.cn/news/")
ret.encoding = ret.apparent_encoding  # 指定编码等于原始页面编码

# 2. 解析：获取想要的指定内容 beautifulsoup
soup = BeautifulSoup(ret.text, 'html.parser')  # 使用lxml则速度更快

# 如果要加class,则前面加下划线 # 使用属性字典方式
div = soup.find(name='div', attrs={"id":"auto-channel-lazyload-article","class":"article-wrapper"}) 

li_list = div.find_all(name='li')

with open('res.txt','w',encoding='utf-8') as t:
    for li in li_list:
        h3 = li.find(name='h3')
        if not h3:
            continue
        t.write(h3.text+'
')

        a = li.find('a')
        t.write(a.get('href')+'
')

        p = li.find(name='p')
        txt = p.text.split('  ',1)[1]
        t.write(txt+'
')
        t.write('
')

        img = li.find(name='img')
        src = img.get('src')

        filename = src.rsplit('__', maxsplit=1)[1]

        down_img = requests.get(url='https:' + src)
        with open('./img/'+filename, 'wb') as f:
            f.write(down_img.content)

二、登录抽屉

#!/usr/bin/env python
# coding:utf-8

import requests

# 请求头要加，先访问普通网页，伪造得越像浏览器越好
# 1. 先访问网页，获取cookie(未授权）
ret = requests.get(
    url="https://dig.chouti.com/all/hot/recent/1",
    headers={
        'user-agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36', }
)
# print(ret.text)
r1_cookie_dict = ret.cookies.get_dict()

# 2. 登录 发送用户名和密码认证, 带上未授权的cookie
# 需要注意反爬虫策略
response_login = requests.post(
    url="https://dig.chouti.com/login",
    data={
        "phone": "8618912600100",
        "password": "wodemima",
        "oneMonth": "1"
    },
    headers={
        'user-agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36'
    },
    cookies=r1_cookie_dict
)

# print(response_login.text)
# cookie_dict=response_login.cookies.get_dict() # 第二次返回的cookie


# 点赞
r1 = requests.post(
    url="https://dig.chouti.com/link/vote?linksId=20630611",
    headers={
        'user-agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36'},
    cookies=r1_cookie_dict
)
print(r1.text)
# {"result":{"code":"9999", "message":"推荐成功", "data":{"jid":"cdu_53074732774","likedTime":"1530752755154000","lvCount":"21","nick":"aabbccdd","uvCount":"1","voteTime":"小于1分钟前"}}}

requests和bs4的几个小片段：

#!/usr/bin/env python
# coding:utf-8

import requests,re
from bs4 import BeautifulSoup

'''
requests.get(url="http://www.baidu.com")  # requests.request(method="get",url="xxx")
requests.post(url="http://www.baidu.com")  # requests.request(method="post",url="xxx")


可以传的参数：
url: 地址
params: URL中传入的参数
headers: 请求头
cookies: Cookie
data: 数据
    以上必需牢记
'''

ret = requests.get(
    url="https://www.baidu.com/s",
    params={"wd": "王历宏"},  # https://www.baidu.com/s?wd=%E6%9D%8E%E5%81%A5
    headers={
        'user-agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36', },
)
ret.encoding = ret.apparent_encoding
# print(ret.text)

soup = BeautifulSoup(ret.text, 'html.parser')

div = soup.find(name='span', attrs={"class":"nums_text"})
# lis = re.findall("d+",div.text)
# print("".join(lis))

print(div.text)


'''
### json参数
requests.post(
    url="http://www.baidu.com",
    # json={
    #     'name':'alex',
    #     'passwd':'123456',
    # },
    headers={},
    cookies={},

    # 如果搞不清对方是要Form_data 还是payload 就使用下面的方式。
    data=json_dumps({
        'name':'alex',
        'pwd':'123456',
    })
)

'''
## 上传文件


# auth 基本弹窗验证
from requests.auth import HTTPBasicAuth,HTTPDigestAuth

res = requests.get(
    'https://api.github.com/user', auth=HTTPBasicAuth("abc@163.com","11223344")
    # 'https://api.github.com/user', auth=HTTPDigestAuth("abc@163.com","11223344") # 方法不一样
)
print(res.text)


# timeout 超时时间


#  allow_redirects



##  proxies  代理
'''
proxies ={
    "http":"61.172.249.96:80",
    "https":"http://61.185.219.126:3128",
}

ret = requests.get("http://www.proxy360.cn/Proxy",proxies=proxies)


proxies2 = {"http://10.20.1.128":"http://10.10.1.10:5323"}
'''


# 使用代理字典，以及用户名密码
'''
from requests.auth import HTTPProxyAuth

proxy_dict={
    'http':'77.75.105.165',
    'https':'77.75.105.166'
}

auth=HTTPProxyAuth('username','mypwd')

r = requests.get("http://www.google.com",proxies=proxy_dict,auth=auth)
'''

我上交的作业，还是有不少问题。

#!/usr/bin/env python
# coding:utf-8

import requests
from bs4 import BeautifulSoup

username = input("请输入github账号：")
pwd = input("请输入github密码：")
print("请稍等几秒... ")

# 1. 打开登录页
ret1 = requests.get(
    url="https://github.com/login",
    headers={
        'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0',
    }
)
r1_cookie_dict = ret1.cookies.get_dict()  # 首次获取cookie

soup1 = BeautifulSoup(ret1.text, features='lxml')
token1 = soup1.find(name="input", attrs={"name": "authenticity_token"}).get("value")  # 拿到页面token
# print(token1) # 是否取到 authenticity_token


# 2. 登录动作
ret2 = requests.post(
    url="https://github.com/session",
    data={
        "commit": "Sign in",
        "utf8": "✓",
        "authenticity_token": token1,
        "login": username,
        "password": pwd,
    },
    headers={
        'user-agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0',
    },
    cookies=r1_cookie_dict # 带上首次的cookie
)
r2_cookie_dict = ret2.cookies.get_dict() # 获取登录成功后返回的cookie
# print(ret2.text) # 确实是慢了点


# 3. 作业中要求获取个人信息，所以打开个人settings页
ret3 = requests.get(
    url="https://github.com/settings/profile",
    headers={
        'user-agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0',
    },
    cookies=r2_cookie_dict # 带上登录成功后的cookie
)
# print(ret3.text)

# 4. 查找并打印个人信息
soup3 = BeautifulSoup(ret3.text, features='lxml')

user_info_name= soup3.find(name="input", attrs={"name": "user[profile_name]"}).get("value")
user_info_email = soup3.find(name="select", attrs={"name": "user[profile_email]"}).get("option") # 可能有问题
user_info_bio = soup3.find(name="textarea", attrs={"name": "user[profile_bio]"}).get("value")
user_info_url = soup3.find(name="input", attrs={"name": "user[profile_blog]"}).get("value")
user_info_company = soup3.find(name="input", attrs={"name": "user[profile_company]"}).get("value")
user_info_location = soup3.find(name="input", attrs={"name": "user[profile_location]"}).get("value")


print('Name: ',user_info_name)
print('Public email: ',user_info_email)
print('Bio: ',user_info_bio)
print('URL: ',user_info_url)
print('Company: ',user_info_company)
print('Location: ',user_info_location)


'''
以下是API的方式，试过，直接得到字典。

from requests.auth import HTTPBasicAuth

res = requests.get(
    'https://api.github.com/user', auth=HTTPBasicAuth(username, pwd)
)
print(res.text)
'''

以下是老师给的指导意见，真是非常好的反馈：

1.请了解下python的pep8规范

2.你的请求头一定要写完整，不要这么暴露你的爬虫请求，这种行为是不好的习惯。

3.你代码的注释写在文档里最好了。

4.你每个请求一定要try一下这在爬虫里很重要你要保证你的爬虫稳定运行

5.你的代码应该封装成函数

6.你写任何项目的时候注意下项目结构哈

7.同学作业写的很好了，其实生产中bs4还是不多的。pyquery或者路径获取的方式用的很多。