python爬虫基础知识学习笔记-python爬虫需要哪些基础知识

383次阅读

没有评论

b站上学的爬虫，讲解得很细致，对python基础和爬虫基础的学习都有很大的帮助

python爬虫基础知识学习笔记

镜像源（加快下载模块）

国内常用的镜像源有：
阿里云 http://mirrors.aliyun.com/pypi/simple/

中国科技大学 https://pypi.mirrors.ustc.edu.cn/simple/

豆瓣(douban) http://pypi.douban.com/simple/

清华大学 https://pypi.tuna.tsinghua.edu.cn/simple/

中国技术大学 http://pypi.mirrors.ustc.edu.cn/simple/

pip install lxml -i https://pypi.tuna.tsinghua.edu.cn/simple/

1. 爬虫基础（贴吧案例）

爬虫的基本操作百度贴吧小案例（request的使用）

# 打开url，封装请求 from urllib.request import urlopen, Request # 将字典封装为网站参数 from urllib.parse import urlencode # 随机UA(防止ip被封) from fake_useragent import UserAgent

# 获取html def get_html(url): headers = { ‘User-Agent’: UserAgent().chrome } request = Request(url, headers=headers) response = urlopen(request) # print(response.read().decode()) return response.read()

# 保存html到本地 def save_html(filename, html_bytes): with open(filename, ‘wb’) as f: print(‘正在保存’ + filename) f.write(html_bytes)

def main(): context = input(‘请输入要下载的内容：’) num = input(‘请输入要下载的页数：’) base_url = ‘https://tieba.baidu.com/f?ie=utf-8&{}’ for pn in range(int(num)): args = { ‘pn’: pn * 50, ‘kw’: context } args = urlencode(args) # print(args) # print(base_url.format(args)) filename = ‘第’ + str(pn + 1) + ‘页.html’ print(‘开始下载’ + filename) html_bytes = get_html(base_url.format(args)) save_html(filename, html_bytes) print(filename + ‘下载完成’)

if __name__ == ‘__main__’: main()

2. post请求的使用

给网站发送post请求，传递post参数

from urllib.request import urlopen, Request from urllib.parse import urlencode from fake_useragent import UserAgent

url = ‘http://www.zengqiang.club/admin/login’

form_data = { ‘username’: ‘曾强’, ‘password’: ‘ZQZ981004’ } # print(urlencode(form_data)) headers = { ‘User-Agent’: UserAgent().random } # print(headers)

f_data = urlencode(form_data) request = Request(url, data=f_data.encode(), headers=headers) response = urlopen(request) print(response.read().decode())

3. ajax请求的抓取(豆瓣电影排行榜信息抓取）

ajax主要是要在network下去查看url 找到url的参数的含义和规律循环的去访问网址获取数据

from urllib.request import Request, urlopen from fake_useragent import UserAgent

base_url = ‘https://movie.douban.com/j/chart/top_list?type=5&interval_id=100%3A90&action=&start={}&limit=20’

i = 0 while True: headers = { ‘User-Agent’: UserAgent().random } # 将base_url中{}代表的参数传入，封装为完整的url url = base_url.format(i * 50) request = Request(url, headers=headers) response = urlopen(request) info = response.read().decode() if len(info) < 10: break print(info) i += 1

4. 代理的使用

使用代理防止过多的访问导致ip被封使用网站的其他ip

from urllib.request import Request, build_opener from urllib.request import ProxyHandler from fake_useragent import UserAgent

url = ‘http://httpbin.org/get’

headers = { ‘User-Agent’: UserAgent().chrome }

request = Request(url, headers=headers)

# 两种方式:(1是购买使用，2是免费的,网上找) # handler = ProxyHandler({‘http’:’username:password@ip:port’}) # handler = ProxyHandler({‘http’:’ip:port’}) handler = ProxyHandler({‘http’: ‘39.137.107.98:80’}) # 封装成自己的opener opener = build_opener(handler) # 用自定义的opener去发出请求 response = opener.open(request) print(response.read().decode())

5. cookie的使用

使用cookie来完成需要登录而访问的页面两种方式：直接使用cookie和保存cookie到文件在加载使用

from urllib.request import Request, HTTPCookieProcessor, build_opener from urllib.parse import urlencode from fake_useragent import UserAgent

# 登录 login_url = ‘http://www.zengqiang.club/admin/login’

headers = { ‘User-Agent’: UserAgent().chrome }

form_date = { ‘username’: ‘曾强’, ‘password’: ‘ZQZ981004’ } f_date = urlencode(form_date).encode()

request = Request(login_url, headers=headers, data=f_date) handler = HTTPCookieProcessor() opener = build_opener(handler) opener.open(request)

# 登录成功 url = ‘http://www.zengqiang.club/admin/blogs’

request = Request(url, headers=headers) response = opener.open(request) print(response.read().decode())

from urllib.request import Request, HTTPCookieProcessor, build_opener from urllib.parse import urlencode from fake_useragent import UserAgent from http.cookiejar import MozillaCookieJar

# 登录 # 保存cookie到文件 def get_cookie(): login_url = ‘http://www.zengqiang.club/admin/login’ headers = { ‘User-Agent’: UserAgent().chrome } form_date = { ‘username’: ‘曾强’, ‘password’: ‘ZQZ981004’ } f_date = urlencode(form_date).encode() request = Request(login_url, headers=headers, data=f_date) cookie_jar = MozillaCookieJar() handler = HTTPCookieProcessor(cookie_jar) opener = build_opener(handler) opener.open(request) cookie_jar.save(‘cookie.txt’, ignore_expires=True, ignore_discard=True)

# 加载cookie # 范文页面 def use_cookie(): url = ‘http://www.zengqiang.club/admin/blogs’ headers = { ‘User-Agent’: UserAgent().chrome } request = Request(url, headers=headers) cookie_jar = MozillaCookieJar() cookie_jar.load(‘cookie.txt’,ignore_expires=True,ignore_discard=True) handler = HTTPCookieProcessor(cookie_jar) opener = build_opener(handler) response = opener.open(request) print(response.read().decode()) if __name__ == ‘__main__’: get_cookie() use_cookie()

6. URLError的使用

异常处理try,except

from urllib.request import Request, urlopen from fake_useragent import UserAgent from urllib.error import URLError

url = ‘http://www.zengqiang.club/1.html’

headers = { ‘User-Agent’: UserAgent().random }

try: request = Request(url, headers=headers)

response = urlopen(request)

print(response.read().decode()) except URLError as e: if e.args == (): print(e.code) else: print(e.args[0].errno)

7. requests的使用

requests比urllib更方便，代码更少

import requests from fake_useragent import UserAgent

# get请求 # url = ‘https://www.baidu.com/s’ # headers = { # ‘User-Agent’: UserAgent().chrome # } # params = { # ‘wd’: ‘重庆文理学院’ # } # response = requests.get(url, headers=headers, params=params) # response.encoding = ‘utf-8’ # # print(response.url)

# post请求 url = ‘http://www.zengqiang.club/admin/login’ form_data = { ‘username’: ‘曾强’, ‘password’: ‘ZQZ981004’ } headers = { ‘User-Agent’: UserAgent().random } response = requests.post(url, data=form_data, headers=headers)

print(response.text)

8. re的使用（正则表达式）

记忆常用的表达式

python爬虫基础知识学习笔记-python爬虫需要哪些基础知识

import re

str = ‘I love you6.6 forever’ print(‘——-match()从字符串的起始位置开始匹配———‘) m1 = re.match(r’I’, str) m2 = re.match(r’\w’, str) m3 = re.match(r’.’, str) m4 = re.match(r’\D’, str) m5 = re.match(r’\S’, str) m6 = re.match(r’i’, str, re.I) print(m6.group())

print(‘——-serach()扫描整个字符串并返回第一个成功的匹配———‘) s1 = re.search(r’love’, str) s2 = re.search(r’l\w+’, str) s3 = re.search(r’y\w+.\d’, str) print(s3.group())

print(‘——-findAll()查找全部———‘) f1 = re.findall(r’o’, str) print(f1)

print(‘——–练习———‘) str1 = ‘<div><a href=”http://www.python.com”>python官网</a></div>’ t1 = re.findall(r’p\w+[\u4e00-\u9fa5]’, str1) t2 = re.findall(r'<a href=”http://www.python.com”>(.+)</a>’, str1) t3 = re.findall(r'<a href=”(.+)”>’, str1) print(t3)

print(‘———sub() 替换字符串——-‘) su1 = re.sub(r'<div>(.+)</div>’, r'<span>\1</span>’, str1) print(su1)

9. 使用re爬取本网站的首页的博客标题

import requests from fake_useragent import UserAgent import re

url = ‘http://www.zengqiang.club/’

headers = { ‘User-Agent’: UserAgent().random }

response = requests.get(url, headers=headers)

# print(response.text) info = response.text result = re.findall(r'<a href=”/blog/\d+” target=”_blank” class=”m-black m-text-thin”>(.+)</a>’, info) print(result)

10. bs4的使用

方便提取html代码中我们需要的内容

from bs4 import BeautifulSoup from bs4.element import Comment

# 这里需要安装lxml模块 # 国内常用的镜像源有： # 阿里云 http://mirrors.aliyun.com/pypi/simple/ # 中国科技大学 https://pypi.mirrors.ustc.edu.cn/simple/ # 豆瓣(douban) http://pypi.douban.com/simple/ # 清华大学 https://pypi.tuna.tsinghua.edu.cn/simple/ # 中国技术大学 http://pypi.mirrors.ustc.edu.cn/simple/ # pip install lxml -i https://pypi.tuna.tsinghua.edu.cn/simple/ str = ”’ <title>尚学堂</title> <div class=’info’ float=’left’>Welcome to SXT</div> <div class=’info’ float=’right’> <span>Good Good Study</span> <a href=’www.bjsxt.cn’></a> <strong><!–没用–></strong> </div> ”’

soup = BeautifulSoup(str, ‘lxml’) print(soup.title) print(soup.div) print(soup.div.attrs) print(soup.div.get(‘class’)) print(soup.div.get(‘float’)) print(soup.a[‘href’]) print(soup.div.string) print(soup.div.text) print(soup.strong.string) print(type(soup.strong.string))

if type(soup.strong.string) == Comment: print(soup.strong.string) print(soup.strong.prettify()) else: print(soup.strong.text)

str1 = ”’ <title id=”title”>尚学堂</title> <div class=’info’ id=”info” float=’left’>Welcome to SXT</div> <div class=’info’ float=’right’> <span>Good Good Study</span> <a href=’www.bjsxt.cn’></a> <strong><!–没用–></strong> </div> ”’

print(‘————find_all()————-‘) soup1 = BeautifulSoup(str1, ‘lxml’) print(soup1.find_all(‘title’)) print(soup1.find_all(id=’title’)) print(soup1.find_all(class_=’info’)) # class是关键字 print(soup1.find_all(attrs={‘float’: ‘left’}))

print(‘————select() css选择器————-‘) print(soup1.select(‘title’)) print(soup1.select(‘#title’)) print(soup1.select(‘.info’)) print(soup1.select(‘div > span’)) # < 两边要有空格 print(soup1.select(‘div span’)) print(soup1.select(‘div’)) print(soup1.select(‘div’)[1]) print(soup1.select(‘div’)[1].select(‘span’)) print(soup1.select(‘title’)[0].text)

11. xpath的使用

xpath用于获取html想要的内容爬取起点中文网的部分书籍的书名和作者

from lxml import html import requests from fake_useragent import UserAgent

url = “https://www.qidian.com/rank/yuepiao?chn=21″ headers = { ‘User_Agent’: UserAgent().random } response = requests.get(url, headers=headers)

etree = html.etree

e = etree.HTML(response.text)

names = e.xpath(‘//h4/a/text()’) authors = e.xpath(‘//p[@class=”author”]/a[1]/text()’)

# for num in range(len(names)): # print(names[num], “:”, authors[num])

for name, author in zip(names, authors): print(name, “:”, author)

# print(names) # print(authors)

12. pyquery的使用

pyquer用于获取html想要的内容爬取ipipgo代理的ip数据

from pyquery import PyQuery as pq import requests from fake_useragent import UserAgent

url = ‘https://www.shenlongip.com/nn/’

headers = { ‘User-Agent’: UserAgent().chrome }

response = requests.get(url, headers=headers)

doc = pq(response.text)

strs = doc(‘#ip_list tr’)

for num in range(1, len(strs)): ip = strs.eq(num).find(‘td’).eq(1).text() port = strs.eq(num).find(‘td’).eq(2).text() type = strs.eq(num).find(‘td’).eq(5).text() print(ip, “:”, port, “—-“, type)

13. json的使用

主要是json与string之间的转换

import json

str = ‘{“name”:”我的小世界”}’ print(type(str))

# 将字符串转为json对象 obj = json.loads(str) print(type(obj), “:”, obj)

# 将json对象转为字符串 str1 = json.dumps(obj, ensure_ascii=False) print(type(str1), “:”, str1)

# 保存json到文件 json.dump(obj, open(‘json.txt’, ‘w’, encoding=’utf-8′), ensure_ascii=False)

# 从文件中提取数据 str2 = json.load(open(‘json.txt’, encoding=’utf-8′)) print(str2)

14. jsonpath的使用

爬取json数据中我们需要的内容

from jsonpath import jsonpath import requests from fake_useragent import UserAgent import json

# json在线解析：https://www.json.cn/ url = ‘https://www.lagou.com/lbs/getAllCitySearchLabels.json’

headers = { ‘User-Agent’: UserAgent().chrome }

response = requests.get(url, headers=headers) # 两种方式将response转换为json对象 city_names = jsonpath(json.loads(response.text), ‘$..name’) city_codes = jsonpath(response.json(), ‘$..code’)

for city_name, city_code in zip(city_names, city_codes): print(city_name, “:”, city_code)

15. 多线程的使用

多线程主要是为了提高爬取的效率爬取段子网的段子数据（面向对象）

from threading import Thread from fake_useragent import UserAgent import requests from lxml import html from queue import Queue

# 爬取网页类 class Spider_html(Thread): def __init__(self, url_queue, html_queue): Thread.__init__(self) self.url_queue = url_queue self.html_queue = html_queue

def run(self): headers = { ‘User-Agent’: UserAgent().random } while self.url_queue.empty() == False: url = self.url_queue.get() response = requests.get(url, headers=headers) if response.status_code == 200: self.html_queue.put(response.text)

# 解析类 class ParseInfo(Thread): def __init__(self, html_queue): Thread.__init__(self) self.html_queue = html_queue

def run(self): etree = html.etree while self.html_queue.empty() == False: e = etree.HTML(self.html_queue.get()) contents = e.xpath(‘//div[@class=”post-content”]/p/text()’) # print(contents) with open(‘duanzi.txt’,’a’,encoding=’utf-8′)as f: for content in contents: info = content # 控制一行一个段子方便查看 f.write(info+’\n’)

if __name__ == ‘__main__’: # 存储url url_queue = Queue() # 存储内容html html_queue = Queue() base_url = ‘https://duanziwang.com/category/%E7%BB%8F%E5%85%B8%E6%AE%B5%E5%AD%90/{}’ for i in range(1, 11): new_url = base_url.format(i) url_queue.put(new_url) # print(new_url)

# 爬取网页 spider_html_list = [] # 开启三个线程 for i in range(0, 3): spider1 = Spider_html(url_queue, html_queue) spider_html_list.append(spider1) spider1.start()

for spider_html in spider_html_list: spider_html.join()

# 解析网页，获取需要的内容 parse_list = [] for i in range(0, 3): parse = ParseInfo(html_queue) parse_list.append(parse) parse.start() for parse in parse_list: parse.join()

16. 云打码的使用

云打码主要用于处理登录时输入的验证码需要给一点钱和注册账号 http://www.yundama.com/

# 打码工具类 import http.client, mimetypes, urllib, json, time, requests from PIL import Image

######################################################################

class YDMHttp: apiurl = ‘http://api.yundama.com/api.php’ username = ” password = ” appid = ” appkey = ”

def __init__(self, username, password, appid, appkey): self.username = username self.password = password self.appid = str(appid) self.appkey = appkey

def request(self, fields, files=[]): response = self.post_url(self.apiurl, fields, files) response = json.loads(response) return response

def balance(self): data = {‘method’: ‘balance’, ‘username’: self.username, ‘password’: self.password, ‘appid’: self.appid, ‘appkey’: self.appkey} response = self.request(data) if (response): if (response[‘ret’] and response[‘ret’] < 0): return response[‘ret’] else: return response[‘balance’] else: return -9001

def login(self): data = {‘method’: ‘login’, ‘username’: self.username, ‘password’: self.password, ‘appid’: self.appid, ‘appkey’: self.appkey} response = self.request(data) if (response): if (response[‘ret’] and response[‘ret’] < 0): return response[‘ret’] else: return response[‘uid’] else: return -9001

def upload(self, filename, codetype, timeout): data = {‘method’: ‘upload’, ‘username’: self.username, ‘password’: self.password, ‘appid’: self.appid, ‘appkey’: self.appkey, ‘codetype’: str(codetype), ‘timeout’: str(timeout)} file = {‘file’: filename} response = self.request(data, file) if (response): if (response[‘ret’] and response[‘ret’] < 0): return response[‘ret’] else: return response[‘cid’] else: return -9001

def result(self, cid): data = {‘method’: ‘result’, ‘username’: self.username, ‘password’: self.password, ‘appid’: self.appid, ‘appkey’: self.appkey, ‘cid’: str(cid)} response = self.request(data) return response and response[‘text’] or ”

def decode(self, filename, codetype, timeout): cid = self.upload(filename, codetype, timeout) if (cid > 0): for i in range(0, timeout): result = self.result(cid) if (result != ”): return cid, result else: time.sleep(1) return -3003, ” else: return cid, ”

def report(self, cid): data = {‘method’: ‘report’, ‘username’: self.username, ‘password’: self.password, ‘appid’: self.appid, ‘appkey’: self.appkey, ‘cid’: str(cid), ‘flag’: ‘0’} response = self.request(data) if (response): return response[‘ret’] else: return -9001

def post_url(self, url, fields, files=[]): for key in files: files[key] = open(files[key], ‘rb’); res = requests.post(url, files=files, data=fields) return res.text

###################################################################### def get_code(filename): # 用户名 username = ‘zq666_yh’

# 密码 password = ‘ZQZ981004’

# 软件ＩＤ，开发者分成必要参数。登录开发者后台【我的软件】获得！ appid = 10039

# 软件密钥，开发者分成必要参数。登录开发者后台【我的软件】获得！ appkey = ‘f6248169a3f9857b57e778c52d9f5de2’

# 图片文件 filename = filename

# 验证码类型，# 例：1004表示4位字母数字，不同类型收费不同。请准确填写，否则影响识别率。在此查询所有类型 http://www.yundama.com/price.html codetype = 1005

# 超时时间，秒 timeout = 60

# 检查 if (username == ‘username’): print(‘请设置好相关参数再测试’) else: # 初始化 yundama = YDMHttp(username, password, appid, appkey)

# 登陆云打码 uid = yundama.login(); # print(‘uid: %s’ % uid)

# 查询余额 balance = yundama.balance(); # print(‘balance: %s’ % balance)

# 开始识别，图片路径，验证码类型ID，超时时间（秒），识别结果 cid, result = yundama.decode(filename, codetype, timeout); # print(‘cid: %s, result: %s’ % (cid, result)) return result ######################################################################

if __name__ == ‘__main__’: img = ‘yzm1.jpg’ code = get_code(img) print(code)

# 使用 import requests from fake_useragent import UserAgent from 爬虫学习.ydm_util import get_code

def get_image(): img_url = ‘http://www.yundama.com/index/captcha’ response = session.get(img_url, headers=headers) with open(‘yzm.jpg’, ‘wb’)as f: f.write(response.content) code = get_code(‘yzm.jpg’) print(code) return code

def do_login(code): login_url = ‘http://www.yundama.com/index/login?’ f_data = { ‘username’: ‘zq666_yh’, ‘password’: ‘ZQZ981004’, ‘utype’: ‘1’, ‘vcode’: code } response = session.get(login_url, headers=headers, params=f_data) print(response.text)

# 三个操作必须在同一个会话下进行 if __name__ == ‘__main__’: session = requests.Session() index_url = ‘http://www.yundama.com/’ headers = { ‘User-Agent’: UserAgent().random } response = session.get(index_url, headers=headers) code = get_image() do_login(code)

17. selenium的使用

selenium主要你用于打开浏览器测试，并控制浏览器进行一些操作需要现在python安装目录下的script中放置浏览器驱动：如chromedriver.exe

from selenium import webdriver

chrome = webdriver.Chrome()

chrome.get(‘http://www.zengqiang.club’)

# chrome.save_screenshot(‘zqclub.jpg’)

# html = chrome.page_source # print(html)

id_content = chrome.find_element_by_id(‘run_time’).text print(id_content)

chrome.find_element_by_name(‘query’).send_keys(‘爬虫’) chrome.find_element_by_class_name(‘search’).click() chrome.save_screenshot(‘爬虫.jpg’) print(chrome.current_url) # 关闭当前页 chrome.close()

# 获取当前页面Cookie print(chrome.get_cookies())

chrome.quit()

18. 练习-爬取360电影信息

练习使用四种爬取方式xpath,re,bs4,pyquery

import requests from fake_useragent import UserAgent from lxml import html from random import randint from time import sleep from bs4 import BeautifulSoup import re from pyquery import PyQuery

# 获取页面的html代码 def get_html(url): headers = { ‘User-Agent’: UserAgent().random } # 暂停2-6秒，使更像人的操作 sleep(randint(2, 6)) response = requests.get(url, headers=headers) response.encoding = ‘utf-8’ if response.status_code == 200: return response.text else: return None

# 解析首页（得到电影信息的url） def parse_index(index_html): # ——pq——– doc = PyQuery(index_html) moive_a = doc(‘ul.list.g-clear a’) moive_urls = [] for a in moive_a: moive_urls.append(a.attrib[‘href’])

# ——re——– # moive_urls = re.findall(r'<a class=”js-tongjic” href=”(.+)”>’, index_html)

# ——bs4——– # soup = BeautifulSoup(index_html, ‘lxml’) # moive_a = soup.select(‘ul.list.g-clear a’) # # print(moive_a) # moive_urls = [] # for a in moive_a: # moive_urls.append(a[‘href’])

# ——xpath——– # etree = html.etree # e = etree.HTML(index_html) # moive_urls = e.xpath(‘//ul[@class=”list g-clear”]//a/@href’)

return [‘https://www.360kan.com{}’.format(url) for url in moive_urls]

# 解析电影信息，得到需要的内容 def parse_info(movie_html): # ——pq——– doc = PyQuery(movie_html) name = doc(‘h1’).text() types = doc(‘p.item > a.cat’).text() actors = doc(‘p.item.item-actor > a’).text()

# ——re——– # name = re.findall(r'<h1>(.+)</h1>’, movie_html)[0] # types = re.findall(r’class=”cat.+href.+”>(.+)</’, movie_html) # actors = re.findall(r'<a class=”name” href=”.+”>(.+)</a>’, movie_html)

# ——bs4——– # soup = BeautifulSoup(movie_html, ‘lxml’) # name = soup.select(‘h1’)[0].text # type = soup.select(‘p.item’)[0].select(‘a’) # types = [] # for t in type: # types.append(t.text) # actor = soup.select(‘p.item.item-actor’)[0].select(‘a’) # actors = [] # for a in actor: # actors.append(a.text)

# ——xpath——– # etree = html.etree # e = etree.HTML(movie_html) # name = e.xpath(‘//h1/text()’)[0] # types = e.xpath(‘//p[@class=”item”][1]/a/text()’) # actors = e.xpath(‘//p[@class=”item item-actor”]/a/text()’) return { ‘name’: name, ‘types’: types, ‘actors’: actors }

# 主方法，遍历电影url，打印爬取的数据 def main(): index_url = ‘https://www.360kan.com/dianying/list.php?year=all&area=all&act=all&cat=all’ index_html = get_html(index_url) moive_urls = parse_index(index_html) print(moive_urls) for url in moive_urls: moive_html = get_html(url) moive = parse_info(moive_html) print(moive)

if __name__ == ‘__main__’: main()

19. 练习-爬取虎牙直播正在直播的主播信息

使用selenium爬取

from selenium import webdriver from time import sleep

driver = webdriver.Chrome()

url = ‘https://www.huya.com/g/2356’

driver.get(url)

num = 1 while True: print(‘第’, str(num), ‘页————‘) num += 1 sleep(5) html = driver.page_source titles = driver.find_elements_by_xpath(‘//a[@class=”title new-clickstat j_live-card”]’) anthors = driver.find_elements_by_xpath(‘//i[@class=”nick”]’) audiences = driver.find_elements_by_xpath(‘//i[@class=”js-num”]’)

for title, anthor, audience in zip(titles, anthors, audiences): print(title.text, ‘—‘, anthor.text, ‘—‘, audience.text) if html.find(‘laypage_next’) != -1: driver.find_element_by_xpath(‘//a[@class=”laypage_next”]’).click() else: break

20. selenium滚动条的使用

有些网页需要滚动才会显示所有内容爬取京东商品信息

from selenium import webdriver from time import sleep

url = ‘https://search.jd.com/Search?keyword=iqoo&enc=utf-8&pvid=1c71f2514c724500b5c4e7f4dc58c1f2’

driver = webdriver.Chrome() driver.get(url)

js = ‘document.documentElement.scrollTop=100000’ driver.execute_script(js)

sleep(3) html = driver.page_source

names = driver.find_elements_by_xpath(‘//div[@class=”gl-i-wrap”]//a/em’) prices = driver.find_elements_by_xpath(‘//div[@class=”gl-i-wrap”]//strong/i’) print(len(names))

for name, price in zip(names, prices): print(name.text, ‘:’, price.text)

21. 练习-图虫网首页所有组图的爬取

import requests from fake_useragent import UserAgent from lxml import html from selenium import webdriver

def get_group_urls(): driver = webdriver.Chrome() index_url = ‘https://tuchong.com/’ driver.get(index_url) index_html = driver.page_source # print(index_html) etree = html.etree e = etree.HTML(index_html) group_urls = e.xpath(‘//div[@class=”post-item”]/a[1]/@href’) return group_urls

def get_group_html(group_urls): etree = html.etree headers = {‘User_Agent’: UserAgent().random} group_num = 1 for url in group_urls: group_name = ‘group’ + str(group_num) group_num += 1 response = requests.get(url, headers=headers) e = etree.HTML(response.text) # print(response.text) img_urls = e.xpath(‘//article[@class=”post-content”]//img[@class=”multi-photo-image”]/@src’) print(img_urls) for img_url in img_urls: img_name = img_url[img_url.rfind(‘/’) + 1:] save_img(img_url, group_name, img_name)

def save_img(img_url, group_num, img_name): headers = {‘User_Agent’: UserAgent().random} response = requests.get(img_url, headers=headers) group_name = ‘group’ + str(group_num) with open(‘img/’ + group_name + ‘-‘ + img_name, ‘wb’) as f: f.write(response.content)

def main(): group_urls = get_group_urls() get_group_html(group_urls)

if __name__ == ‘__main__’: main()

22. 双色球案例（存入数据到数据库）

链接数据库并插入爬取的数据

import requests from fake_useragent import UserAgent from lxml import html import pymysql

def get_html(url): headers = { ‘User-Agent’: UserAgent().random } response = requests.get(url, headers=headers) return response.text

def save_mysql(trs, date_time): client = pymysql.connect(host=’localhost’, port=3306, user=’root’, password=’ZQZ981004′, charset=’utf8′, db=’python’) print(‘数据库链接成功’) cursor = client.cursor() sql = ‘insert into double_ball values(0,%s,%s,%s)’

for tr, time in zip(trs, date_time): # 提取红球 red_ball = ‘-‘.join(tr.xpath(‘./td[@class=”chartBall01″]/text()’)) # 提取蓝球 blue_ball = tr.xpath(‘./td[@class=”chartBall02″]/text()’)[0] print(“第 ” + time + “期—红球是：” + red_ball + ” 蓝球：” + blue_ball) cursor.execute(sql, [time, red_ball, blue_ball]) client.commit()

cursor.close() client.close() print(‘保存数据完成’)

def main(): url = ‘https://datachart.500.com/ssq/’ html_ = get_html(url) etree = html.etree e = etree.HTML(html_) data_time = e.xpath(‘//tbody[@id=”tdata”]/tr/td[@align=”center”]/text()’) trs = e.xpath(‘//tbody[@id=”tdata”]/tr[not(@class)]’) save_mysql(trs, data_time)

if __name__ == ‘__main__’: main()

23. 爬虫新写法（规范，类）

分离所有的方法使用类更专业

import requests from fake_useragent import UserAgent from lxml import etree

# url管理 class URLManager(object): def __init__(self): self.new_url = [] self.old_url = []

# 获取一个url def get_new_url(self): url = self.new_url.pop() self.old_url.append(url) return url

# 增加一个url def add_new_url(self, url): if url not in self.new_url and url and url not in self.old_url: self.new_url.append(url)

# 增加多个url def add_new_urls(self, urls): for url in urls: self.add_new_url(url)

# 判断是否还有可以爬取的url def has_new_url(self): return self.get_new_url_size() > 0 # 获取可以爬取的数量

def get_new_url_size(self): return len(self.new_url)

# 获取已经爬取的数量 def get_old_url_size(self): return len(self.old_url)

# 爬取 class Downloader: def download(self, url): response = requests.get(url, headers={“User-Agent”: UserAgent().random}) if response.status_code == 200: response.encoding = ‘utf-8’ return response.text else: return None

# 解析 class Parser: def parse(self, html): e = etree.HTML(html) datas = self.parse_info(e) #datas = [span.xpath(‘string(.)’) for span in e.xpath(‘//div[@class=”content”]/span[1]’)] urls = self.parse_urls(e) #urls = [ ‘https://www.qiushibaike.com{}’.format(url) for url in e.xpath(‘//ul[@class=”pagination”]/li/a/@href’)] return datas, urls

def parse_info(self, e): spans = e.xpath(‘//div[@class=”content”]/span[1]’) datas = [] for span in spans: datas.append(span.xpath(‘string(.)’)) return datas

def parse_urls(self, e): base_url = ‘https://www.qiushibaike.com{}’ urls = [] for url in e.xpath(‘//ul[@class=”pagination”]/li/a/@href’): urls.append(base_url.format(url)) return urls

# 数据处理 class DataOutPut: def save(self, datas): with open(‘duanzi.txt’, ‘a’, encoding=’utf-8′) as f: for data in datas: f.write(data)

# 调度 class DiaoDu: def __init__(self): self.downloader = Downloader() self.url_manager = URLManager() self.parser = Parser() self.data_saver = DataOutPut()

def run(self, url): self.url_manager.add_new_url(url) while self.url_manager.has_new_url(): url = self.url_manager.get_new_url() html = self.downloader.download(url) data, urls = self.parser.parse(html) self.data_saver.save(data) self.url_manager.add_new_urls(urls)

if __name__ == ‘__main__’: diao_du = DiaoDu() diao_du.run(‘https://www.qiushibaike.com/text/page/1/’)

神龙|纯净稳定代理IP免费测试>>>>>>>>天启|企业级代理IP免费测试>>>>>>>>IPIPGO|全球住宅代理IP免费测试

发表于：Python爬虫

2022-11-01

# Python爬虫

复制链接

赏