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爬虫练习题（一）

2022-04-23 14:11:00 【张立梵】

Don't just follow the path .Make your own trail .
不要只是沿着路走，走你自己的路。

这次发稿具有极强的纪念意义，生日当天发稿，开启了我网络笔记的生涯，以及加深了对爬虫的无限热爱，希望大家能够给予我支持！！！第一次发稿还请多多支持！！！以后精彩不断哦。

10.(选做题1)目标网站https://www.sogou.com/
要求:
1.用户输入要搜索的内容,起始页和终止页
2.根据用户输入的内容爬取相关页面的源码
3.把获取下来的数据保存到本地

import requests
word = input("请输入搜索内容")
start = int(input("请输入起始页"))
end = int(input("请输入结束页"))
headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36 Edg/100.0.1185.44'
}
for n in range(start, end + 1):
    url = f'https://www.sogou.com/web?query={word}&page={n}'
    # print(url)
    response = requests.get(url, headers=headers)
    with open(f'{word}的第{n}页。html', "w", encoding="utf-8")as file:
        file.write(response.content.decode("utf-8"))

一、分析网页

1.先录入网址

python - 搜狗搜索 (sogou.com)https://www.sogou.com/web?query=python&_ast=1650447467&_asf=www.sogou.com&w=01029901&p=40040100&dp=1&cid=&s_from=result_up&sut=7606&sst0=1650447682406&lkt=0%2C0%2C0&sugsuv=1650427656976942&sugtime=1650447682406 2.分别搜索 “Python”，“中国”并进行网址对比。

中国 - 搜狗搜索 (sogou.com)https://www.sogou.com/web?query=%E4%B8%AD%E5%9B%BD&_ast=1650446881&_asf=www.sogou.com&w=01029901&p=40040100&dp=1&cid=&s_from=result_up&sut=9319&sst0=1650447465594&lkt=0%2C0%2C0&sugsuv=1650427656976942&sugtime=1650447465594

3.把每个参数以"&"符分割开来

结论：（1）参数query是搜索对象，中文字符会进行转义（转义后编码不用记忆）

（2）参数ie是转义的编码类型，以"utf-8"为例，该参数可以在Network- Payload-ie=utf-8，有些包也可以在Network-Response-charset='utf-8', 如图：

4.但是有这俩个参数还不能满足试题的翻页爬取需求，所以我们要手动翻页再进行检查

https://www.sogou.com/web?query=python&page=2&ie=utf8

5.终于到了最关键的时刻了！我们找到了规律，以及重要参数的含义，就可以构建通用的 URL了，如图：

url = f'https://www.sogou.com/web?query={word}&page={n}'

# 用变量把可变参数赋值，这样就构建好了一个新的URL

二、找参数

https://www.sogou.com/web?query=Python&_asf=www.sogou.com&_ast=&w=01019900&p=40040100&ie=utf8&from=index-nologin&s_from=index&sut=12736&sst0=1650428312860&lkt=0%2C0%2C0&sugsuv=1650427656976942&sugtime=1650428312860
https://www.sogou.com/web?query=java&_ast=1650428313&_asf=www.sogou.com&w=01029901&p=40040100&dp=1&cid=&s_from=result_up&sut=10734&sst0=1650428363389&lkt=0%2C0%2C0&sugsuv=1650427656976942&sugtime=1650428363389
https://www.sogou.com/web?query=C%E8%AF%AD%E8%A8%80&_ast=1650428364&_asf=www.sogou.com&w=01029901&p=40040100&dp=1&cid=&s_from=result_up&sut=11662&sst0=1650428406805&lkt=0%2C0%2C0&sugsuv=1650427656976942&sugtime=1650428406805
https://www.sogou.com/web?
https://www.sogou.com/web?query=Python&
https://www.sogou.com/web?query=Python&page=2&ie=utf8

 'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36 Edg/100.0.1185.44'
'cookie' = "IPLOC=CN3600; SUID=191166B6364A910A00000000625F8708; SUV=1650427656976942; browerV=3; osV=1; ABTEST=0|1650428297|v17; SNUID=636A1DCD7B7EA775332A80CB7B347D43; sst0=663; ld=llllllllll2AgcuYlllllpJK6jclllllHuYSpyllllDlllllVllll5@@@@@@@@@@; LSTMV=229,37; LCLKINT=1424"
'URl' = "https://www.sogou.com/web?query=Python&_ast=1650429998&_asf=www.sogou.com&w=01029901&cid=&s_from=result_up&sut=5547&sst0=1650430005573&lkt=0,0,0&sugsuv=1650427656976942&sugtime=1650430005573"
url="https://www.sogou.com/web?query={}&page={}:

# UA要以字典形式被headers接收

1.headers的错误：

" ":" ",      
# 构建字典的格式，','千万千万别忘了
# headers是关键字不能写错了，写错的话就会有如下报错


import requests
url = "https://www.bxwxorg.com/"
hearders = {
    'cookie':'Hm_lvt_46329db612a10d9ae3a668a40c152e0e=1650361322; mc_user={"id":"20812","name":"20220415","avatar":"0","pass":"2a5552bf13f8fa04f5ea26d15699233e","time":1650363349}; Hm_lpvt_46329db612a10d9ae3a668a40c152e0e=1650363378',
    'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36 Edg/100.0.1185.44'
}
response = requests.get(url, hearders=hearders)
print(response.content.decode("UTF-8"))


Traceback (most recent call last):
  File "D:/pythonproject/第二次作业.py", line 141, in <module>
    response = requests.get(url, hearders=hearders)
  File "D:\python37\lib\site-packages\requests\api.py", line 75, in get
    return request('get', url, params=params, **kwargs)
  File "D:\python37\lib\site-packages\requests\api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
TypeError: request() got an unexpected keyword argument 'hearders'

# 原因：三个hearders写的一致，但是headers是关键字，所以报类型错误




# 但是写成heades会有另一种报错形式

import requests
word = input("请输入搜索内容")
start = int(input("请输入起始页"))
end = int(input("请输入结束页"))
heades = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36 Edg/100.0.1185.44'
}
for n in range(start, end + 1):
    url = f'https://www.sogou.com/web?query={word}&page={n}'
    # print(url)
    response = requests.get(url, headers=headers)
    with open(f'{word}的第{n}页。html', "w", encoding="utf-8")as file:
        file.write(response.content.decode("utf-8"))


Traceback (most recent call last):
  File "D:/pythonproject/第二次作业.py", line 117, in <module>
    response = requests.get(url, headers=headers)
NameError: name 'headers' is not defined

# 原因：三个hearders写的不一致，所以报名称错误




# 正确写法是，最好不要写错！

import requests
url = "https://www.bxwxorg.com/"
headers = {
    'cookie':'Hm_lvt_46329db612a10d9ae3a668a40c152e0e=1650361322; mc_user={"id":"20812","name":"20220415","avatar":"0","pass":"2a5552bf13f8fa04f5ea26d15699233e","time":1650363349}; Hm_lpvt_46329db612a10d9ae3a668a40c152e0e=1650363378',
    'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36 Edg/100.0.1185.44'
}
response = requests.get(url, headers=headers)
print(response.content.decode("UTF-8"))

三、循环

for n in range(start, end + 1):

# 为什么是'end+1'呢：因为range函数的范围区间是左闭右开的所以真实的end值取不到，在后面加1就可以取到前一个真实值了

因为是翻页爬取，需要用到每一页的URL，所以要把构建的URL调入循环中

四、requests的基本介绍：(江湖人称 "urllib3" )

1.安装：Win + R --> cmd -->输入pip install requests

# 下载后如果不能调用是因为：模块安装在Python自带的环境中，自己用的虚拟环境没有这个库，要指定环境

# 指定环境 : 终端输入where python找到安装路径 --> File --> setting --> project --> project interpreter --> 找到设置图标齿轮 --> Add --> system interpreter --> ... --> (where python中的路径) --> OK --> Apply应用 --> OK

2.爬虫的请求模块urllib.request模块 (urllib3)

(1)常用方法：

urllib.request.urlopen("网址")

作用：向网站发起一次请求，并获取相应

字节流 = response.read().decode('utf-8')

urllib.request request("网址", headers="字典")

# 因为urlopen() 不支持重构User-Agent

(2)requests模块

(2-1)request的常用用法：

requsts.get(网址）

(2-2)响应的对象response的方法：

response.text返回Unicode格式的数据(str)