requests模块的进阶使用

代理

• 代理服务器,可以接受请求后将其转发,从而更换我们请求所对应的ip
• 匿名度
  • 高匿:啥也不知道
  • 匿名:服务器会知道我使用了代理但是不知道我的真实ip
  • 透明:服务器会知道我使用了代理并且知道我的真实ip
• 类型
  • http:意味着这个服务器只能转发http协议的请求
  • https:只能转发https协议的请求
• 免费代理
  • http://www.goubanjia.com/
  • 快代理
  • http://http.zhiliandaili.cn/
• 为了避免ip失效,我们应该构建一个代理池,里面存放可用的代理
• 代理池的构建也是通过爬虫实现的,我们可以去快代理上去爬取,但是频繁访问快代理也是会被封的,所以我们需要去买一些代理来爬取快代理,有点以小博大的意思(这里的代理选取主要用于举例,主要是方法)

# 代理池的用法
# ip_pool = [
#     {‘https‘:‘https://171.35.149.66:9999‘},
#     {‘https‘:‘https://171.35.149.66:9999‘},
#     ...
# ]

# url = ‘https://www.baidu.com/s?wd=ip‘
# page_text = requests.get(url=url,headers=headers,proxies=random.choice(ip_pool)).text
# with open(‘ip.html‘,‘w‘,encoding=‘utf-8‘) as fp:
#     fp.write(page_text)

import requests
from lxml import etree
import random

headers = {
    ‘User-Agent‘:‘Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36‘,
    ‘Connection‘:‘close‘
}

# 去代理精灵购买代理,并通过爬虫快速提取到购买的代理ip
ip_url = ‘.....‘(购买后会生成一个url连接)
page_text = requests.get(url=ip_url,headers=headers).text
tree = etree.HTML(page_text)
ip_pool = tree.xpath(‘//body//text()‘)

# 爬取快代理
url = ‘https://www.kuaidaili.com/free/inha/%d/‘
proxy_http_list = []
proxy_https_list = []
for page in range(1,20):
    new_url = format(url%page)
    page_text = requests.get(new_url,headers=headers,proxies=random.choice(ip_pool)).text
    tree = etree.HTML(page_text)
    tr_list = tree.xpath(‘//*[@id="list"]/table//tr‘)[1:]  # 注意!tbody不能出现在xpath表达式中
    
    for tr in tr_list:
        ip = tr.xpath(‘./td[1]/text()‘)[0]
        port = tr.xpath(‘./td[2]/text()‘)[0]
        t_type = tr.xpath(‘./td[4]/text()‘)[0]
        cip = t_type+‘://‘+ip+‘:‘+port
        dic = {
           t_type: cip
        }
        if t_type == ‘HTTP‘:
            proxy_http_list.append(dic)
        else:
            proxy_https_list.append(dic)

print(len(proxy_http_list),len(proxy_https_list))   #查看个数

# 检查代理是否可用
# 让其随意访问一个网站(http/https要分开),如果状态码为200,即为可用

for ip in proxy_http_list:
    response = requests.get(‘http://...‘,headers=headers,proxies=ip)
    if response.status_code == ‘200‘:
        ... #将可用ip存储起来

cookie

• cookie的处理

  • cookie的作用:可以让浏览器记录和保存我们当前客户端的某些状态
  • 手动处理:将cookie封装到headers中
  • 自动处理:创建一个session对象,该对象可以像requests一样进行请求发送.不同之处在于如果使用session进行请求发送的过程中产生了cookie,则cookie会自动保存在session对象中.

• 模拟登陆

• 实现验证码识别

  • 超级鹰 http://www.chaojiying.com/
    • 注册(用户中心)
    • 登录
      • 创建一个软件:
      • 下载事例代码
  • 打码兔
  • 云打码

• 动态变化的请求参数

  • 通常情况下动态变化的请求参数都会被隐藏在前台页面源码中

• 模拟登陆失败的话检查以下原因

  • 核对用户名和密码有无出错
  • 核对验证码是否正确
  • 检查请求参数是否为动态变化的
  • 最后检查cookie

# 对雪球网的新闻数据进行爬取  https://xueqiu.com/
# 手动处理cookie
import requests
headers = {
    ‘User-Agent‘:‘Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36‘,
    ‘Cookie‘:‘acw_tc=2760820e15998126544901640efe534c6e7b7ac5b225fee97814d7b22bf4a5; xq_a_token=4db837b914fc72624d814986f5b37e2a3d9e9944; xqat=4db837b914fc72624d814986f5b37e2a3d9e9944; xq_r_token=2d6d6cc8e57501dfe571d2881cabc6a5f2542bf8; xq_id_token=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJ1aWQiOi0xLCJpc3MiOiJ1YyIsImV4cCI6MTYwMDQ4MzAwNywiY3RtIjoxNTk5ODEyNjE5NDkzLCJjaWQiOiJkOWQwbjRBWnVwIn0.Uf32VSRz3a-_uxv4lrdqq3K8GTOBcz4EIhTbL1pV3eTbFOv5JU89CmD2svrgJ6cBpUys0LGNuoR9l82uemyMjz5d3vtOijWOLui-VEcFGm1_U4gV90OsB9cH7CG7FE8xy0_O300VyaFjHtV6dDOfbrJdUz3ijLMntMoF3X_0454gUxqYZ78cAY5zwKYpt-BEUQFfJ2eAccbO2Gu432-fK3I6YT5kjkxHr-L0dIZIuEkqKNZBkzTG_dyoADaUG7vs-RL7N8gdWNaL3dfyeB2i8WsoLNiML8fyK5r-ujROfrhUKC8AcIof2fXT5a0mRXfG2ZLUzVE3udvqxyPhrc7XZA; u=601599812654691; Hm_lvt_1db88642e346389874251b5a1eded6e3=1599812658; Hm_lpvt_1db88642e346389874251b5a1eded6e3=1599812658; device_id=24700f9f1986800ab4fcc880530dd0ed‘
}

url = ‘https://xueqiu.com/statuses/hot/listV2.json?since_id=-1&max_id=105684&size=15‘
page_text = requests.get(url=url,headers=headers).json()
print(page_text)

#创建session对象,自动处理cookie
import requests
headers = {
    ‘User-Agent‘:‘Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36‘
}
session = requests.Session()
session.get(‘https://xueqiu.com/‘,headers=headers)  #先去访问一次主页,获取cookie

url = ‘https://xueqiu.com/statuses/hot/listV2.json?since_id=-1&max_id=105684&size=15‘
page_text = session.get(url=url,headers=headers).json()
print(page_text)

模拟登陆

# 超级鹰定义的类
import requests
from hashlib import md5

class Chaojiying_Client(object):

    def __init__(self, username, password, soft_id):
        self.username = username
        password =  password.encode(‘utf8‘)
        self.password = md5(password).hexdigest()
        self.soft_id = soft_id
        self.base_params = {
            ‘user‘: self.username,
            ‘pass2‘: self.password,
            ‘softid‘: self.soft_id,
        }
        self.headers = {
            ‘Connection‘: ‘Keep-Alive‘,
            ‘User-Agent‘: ‘Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0)‘,
        }

    def PostPic(self, im, codetype):
        """
        im: 图片字节
        codetype: 题目类型 参考 http://www.chaojiying.com/price.html
        """
        params = {
            ‘codetype‘: codetype,
        }
        params.update(self.base_params)
        files = {‘userfile‘: (‘ccc.jpg‘, im)}
        r = requests.post(‘http://upload.chaojiying.net/Upload/Processing.php‘, data=params, files=files, headers=self.headers)
        return r.json()

    def ReportError(self, im_id):
        """
        im_id:报错题目的图片ID
        """
        params = {
            ‘id‘: im_id,
        }
        params.update(self.base_params)
        r = requests.post(‘http://upload.chaojiying.net/Upload/ReportError.php‘, data=params, headers=self.headers)
        return r.json()

# 识别古诗文网的验证码 https://www.gushiwen.org/
# 模拟登陆

# 获取验证码
def transformImgData(img_path,img_type):
    chaojiying = Chaojiying_Client(UserName, Password, 软件id)  # 此处依次输入超级鹰用户名,密码和生成的软件id
    im = open(img_path, ‘rb‘).read()
    return chaojiying.PostPic(im, img_type)[‘pic_str‘]

import requests
headers = {
    ‘User-Agent‘:‘Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36‘,
}
url = ‘https://so.gushiwen.cn/user/login.aspx‘

# session获取cookie
session = requests.Session()

# 获取验证码图片
page_text = session.get(url=url,headers=headers).text
tree = etree.HTML(page_text)
img_url = ‘https://so.gushiwen.cn‘+tree.xpath(‘//*[@id="imgCode"]/@src‘)[0]  #验证码图片
img_data = session.get(url=img_url,headers=headers).content
with open(‘./code.jpg‘,‘wb‘) as fp:
    fp.write(img_data)

# 获取动态数据
__VIEWSTATEGENERATOR = tree.xpath(‘//*[@id="__VIEWSTATEGENERATOR"]/@value‘)  
__VIEWSTATE = tree.xpath(‘//*[@id="__VIEWSTATE"]/@value‘)

# 解析出验证码
code = transformImgData(‘./code.jpg‘,1004)
print(code)

# 模拟登陆
login_url = ‘https://so.gushiwen.cn/user/login.aspx?from=‘
data = {
    ‘__VIEWSTATE‘: __VIEWSTATE,
    ‘__VIEWSTATEGENERATOR‘: __VIEWSTATEGENERATOR,
    ‘from‘: ‘‘,
    ‘email‘: ‘...‘,      #填写古诗文网账号和密码
    ‘pwd‘: ‘...‘,
    ‘code‘: code,
    ‘denglu‘: ‘登录‘,
}
login_page = session.post(url=login_url,headers=headers,data=data).text
with open(‘./login.html‘,‘w‘,encoding=‘utf-8‘) as fp:
    fp.write(login_page)

单线程+多任务异步协程

• 协程

  • 在函数(特殊函数)定义的时候,使用async修饰,函数调用后,内部语句不会立即执行,而是会返回一个协程对象

• 任务对象

  • 任务对象=高级的协程对象(进一步封装)=特殊的函数
  • 任务对象必须要注册到时间循环对象中
  • 给任务对象绑定回调:爬虫的数据解析中

• 事件循环

  • 当做是一个装载任务对象的容器
  • 当启动事件循环对象的时候,存储在内的任务对象会异步执行

• 特殊函数内部不能写不支持异步请求的模块,如time,requests...否则虽然不报错但实现不了异步

  • time.sleep -- asyncio.sleep
  • requests -- aiohttp

import asyncio
import time

start_time = time.time()
async def get_request(url):
    await asyncio.sleep(2)
    print(url,‘下载完成!‘)

urls = [
    ‘www.1.com‘,
    ‘www.2.com‘,
]

task_lst = []  # 任务对象列表
for url in urls:
    c = get_request(url)  # 协程对象
    task = asyncio.ensure_future(c)  # 任务对象
    # task.add_done_callback(...)   # 绑定回调
    task_lst.append(task)

loop = asyncio.get_event_loop()  # 事件循环对象
loop.run_until_complete(asyncio.wait(task_lst))  # 注册,手动挂起

线程池+requests模块

# 线程池
import time
from multiprocessing.dummy import Pool

start_time = time.time()
url_list = [
    ‘www.1.com‘,
    ‘www.2.com‘,
    ‘www.3.com‘,
]
def get_request(url):
    print(‘正在下载...‘,url)
    time.sleep(2)
    print(‘下载完成!‘,url)

pool = Pool(3)
pool.map(get_request,url_list)
print(‘总耗时:‘,time.time()-start_time)

实现爬虫的加速(两种方法)

起一个flask服务端

from flask import Flask
import time

app = Flask(__name__)

@app.route(‘/bobo‘)
def index_bobo():
    time.sleep(2)
    return ‘hello bobo!‘

@app.route(‘/jay‘)
def index_jay():
    time.sleep(2)
    return ‘hello jay!‘

@app.route(‘/tom‘)
def index_tom():
    time.sleep(2)
    return ‘hello tom!‘

if __name__ == ‘__main__‘:
    app.run(threaded=True)

aiohttp模块+单线程多任务异步协程

import asyncio
import aiohttp
import requests
import time

start = time.time()
async def get_page(url):
    # page_text = requests.get(url=url).text
    # print(page_text)
    # return page_text
    async with aiohttp.ClientSession() as s:  #生成一个session对象
        async with await s.get(url=url) as response:
            page_text = await response.text()
            print(page_text)
    return page_text

urls = [
    ‘http://127.0.0.1:5000/bobo‘,
    ‘http://127.0.0.1:5000/jay‘,
    ‘http://127.0.0.1:5000/tom‘,
]
tasks = []
for url in urls:
    c = get_page(url)
    task = asyncio.ensure_future(c)
    tasks.append(task)
loop = asyncio.get_event_loop()
loop.run_until_complete(asyncio.wait(tasks))

end = time.time()
print(end-start)

# 异步执行!
# hello tom!
# hello bobo!
# hello jay!
# 2.0311079025268555

requests模块+线程池

import time
import requests
from multiprocessing.dummy import Pool

start = time.time()
urls = [
    ‘http://127.0.0.1:5000/bobo‘,
    ‘http://127.0.0.1:5000/jay‘,
    ‘http://127.0.0.1:5000/tom‘,
]
def get_request(url):
    page_text = requests.get(url=url).text
    print(page_text)
    return page_text

pool = Pool(3)
pool.map(get_request, urls)
end = time.time()
print(‘总耗时:‘, end-start)

# 实现异步请求
# hello jay!
# hello bobo!
# hello tom!
# 总耗时: 2.0467123985290527

小结

• 爬虫的加速目前掌握了两种方法:
  • aiohttp模块+单线程多任务异步协程
  • requests模块+线程池
• 爬虫接触的模块有三个:
  • requests
  • urllib
  • aiohttp
• 接触了一下flask开启服务器

requests模块的进阶使用

原文：https://www.cnblogs.com/straightup/p/13664753.html