Python3爬虫之模拟post登陆及get登陆

一、模拟登陆需要账号，密码的网址

一些不需要登陆的网址操作已经试过了，这次来用Python尝试需要登陆的网址，来利用cookie模拟登陆

由于我们教务系统有验证码偏困难一点，故挑了个软柿子捏，赛氪，https://www.saikr.com

我用的是火狐浏览器自带的F12开发者工具，打开网址输入账号，密码，登陆，如图

可以看到捕捉到很多post和get请求，第一个post请求就是我们提交账号和密码的，

点击post请求的参数选项可以看到我们提交的参数在bian表单数据里，name为账户名，pass为加密后的密码，remember为是否记住密码，0为不记住密码。

我们再来看看headers，即消息头

我们把这些请求头加到post请求的headers后对网页进行模拟登陆，

Cookie为必填项，否则会报错：

{"code":403,"message":"访问超时，请重试，多次出现此提示请联系QQ：1409765583","data":[]}

便可以创建一个带有cookie的opener，在第一次访问登录的URL时，将登录后的cookie保存下来，然后利用带有这个cookie的opener来访问该网址的其他版块，查看登录之后才能看到的信息。

比如我是登陆https://www.saikr.com/login后模拟登陆了“我的竞赛”版块https://www.saikr.com/u/5598522

代码如下： 

import urllib
from urllib import request
from http import cookiejar
login_url = "https://www.saikr.com/login"
postdata ={
"name": "your account","pass": "your password(加密后）"
}
header = {
"Accept":"application/json, text/javascript, */*; q=0.01",
"Accept-Language":"zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2",
"Connection":"keep-alive",
"Host":"www.saikr.com",
"Referer":"https://www.saikr.com/login",
"Cookie":"your cookie",
"Content-Type":"application/x-www-form-urlencoded; charset=UTF-8",
"TE":"Trailers","X-Requested-With":"XMLHttpRequest"
}
postdata = urllib.parse.urlencode(postdata).encode('utf8')
#req = requests.post(url,postdata,header)
#声明一个CookieJar对象实例来保存cookie
cookie = cookiejar.CookieJar()
#利用urllib.request库的HTTPCookieProcessor对象来创建cookie处理器,也就CookieHandler
cookie_support = request.HTTPCookieProcessor(cookie)
 #通过CookieHandler创建opener
opener = request.build_opener(cookie_support)
#创建Request对象
my_url="https://www.saikr.com/u/5598522"
req1 = request.Request(url=login_url, data=postdata, headers=header)#post请求
req2 = request.Request(url=my_url)#利用构造的opener不需要cookie即可登陆，get请求
response1 = opener.open(req1)
response2 = opener.open(req2)
print(response1.read().decode('utf8'))
print(response2.read().decode('utf8'))

到此就告一段落了： 

ps：有点小插曲，当在headers里加入

Accept-Encoding

gzip, deflate, br

时，最后在 print(response1.read().decode('utf8'))时便会报错

UnicodeDecodeError: 'utf-8' codec can't decode byte 0x8b in position 1: invalid start byte

原因：在请求header中设置了'Accept-Encoding': 'gzip, deflate'

参考链接：https://www.cnblogs.com/chyu/p/4558782.html

解决方法：去掉Accept-Encoding后就正常了

二、模拟登陆网址常用方法总结

1.通过urllib库的request库的函数进行请求

from urllib import request
#get请求
------------------------------------------------------
#不加headers
response=request.urlopen(url)
page_source = response.read().decode('utf-8')

#加headers,由于urllib.request.urlopen() 函数不接受headers参数，所以需要构建一个urllib.request.Request对象来实现请求头的设置
req= request.Request(url=url,headers=headers)
response=request.urlopen(req)
page_source = response.read().decode('utf-8')

#post请求
-------------------------------------------------------
postdata = urllib.parse.urlencode(data).encode('utf-8')#必须进行重编码
req= request.Request(url=url,data=postdata,headers=headers)
response=request.urlopen(req)
page_source = response.read().decode('utf-8')
#使用cookie访问其他版块
#声明一个CookieJar对象实例来保存cookie
cookie = cookiejar.CookieJar()
#利用urllib.request库的HTTPCookieProcessor对象来创建cookie处理器,也就CookieHandler
cookie_support = request.HTTPCookieProcessor(cookie)
 #通过CookieHandler创建opener
opener = request.build_opener(cookie_support)
# 将Opener安装位全局，覆盖urlopen函数，也可以临时使用opener.open()函数
#urllib.request.install_opener(opener)
#创建Request对象
my_url="https://www.saikr.com/u/5598522"
req2 = request.Request(url=my_url)
response1 = opener.open(req1)
response2 = opener.open(req2)
#或者直接response2=opener.open(my_url)
print(response1.read().decode('utf8'))
print(response2.read().decode('utf8'))

 

2.通过requests库的get和post函数

import requests
import urllib
import json
#get请求
-----------------------------------------------------------
#method1
url="https://www.saikr.com/"
params={ 'key1': 'value1','key2': 'value2' }
real_url = base_url + urllib.parse.urlencode(params)
#real_url="https://www.saikr.com/key1=value1&key2=value2"
response=requests.get(real_url)
#method2
response=requests.get(url,params)
print(response.text)#<class 'str'>
print(response.content)# <class 'bytes'>

#post请求
login_url = "https://www.saikr.com/login"
postdata ={
"name": "[e-mail]","pass": "my password",
}
header = {
"Accept":"application/json, text/javascript, */*; q=0.01",
"Accept-Language":"zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2",
"Connection":"keep-alive",
"Host":"www.saikr.com",
"Referer":"https://www.saikr.com/login",
"Cookie":"mycookie",
"Content-Type":"application/x-www-form-urlencoded; charset=UTF-8",
"TE":"Trailers","X-Requested-With":"XMLHttpRequest"
}
#requests中的post中传入的data可以不进行重编码
#login_postdata = urllib.parse.urlencode(postdata).encode('utf8')
response=requests.post(url=login_url,data=postdata,headers=header)#<class 'requests.models.Response'>
#以下三种都可以解析结果
json1 = response1.json()#<class 'dict'>
json2= json.loads(response1.text)#<class 'dict'>
json_str = response2.content.decode('utf-8')#<class 'str'>

#利用session维持会话访问其他版块
--------------------------------------------------------------------
login_url = "https://www.saikr.com/login"
postdata ={
"name": "[e-mail]","pass": "my password",
}
header = {
"Accept":"application/json, text/javascript, */*; q=0.01",
"Connection":"keep-alive",
"Referer":"https://www.saikr.com/login",
"Cookie":"mycookie",
}
session = requests.session()
response = session.post(url=url, data=data, headers=headers)
my_url="https://www.saikr.com/u/5598522"
response1 = session.get(url=my_url, headers=headers)
print(response1.json())