Python xpath,JsonPath,bs4的基本使用_python_

//div[@id] //div[@id="maincontent"] 

//@class 

//div[contains(@id, "he")] //div[starts‐with(@id, "he")] 

//div/h1/text() 

//div[@id="head" and @class="s_down"] //title | //price

北京
上海
广州
深圳

from lxml import etree # xpath解析 # 本地文件： etree.parse # 服务器相应的数据 response.read().decode('utf-8') etree.HTML() tree = etree.parse('xpath.html') # 查找url下边的li li_list = tree.xpath('//body/ul/li') print(len(li_list)) # 4 # 获取标签中的内容 li_list = tree.xpath('//body/ul/li/text()') print(li_list) # ['北京', '上海', '广州', '深圳'] # 获取带id属性的li li_list = tree.xpath('//ul/li[@id]') print(len(li_list)) # 3 # 获取id为l1的标签内容 li_list = tree.xpath('//ul/li[@id="l1"]/text()') print(li_list) # ['北京'] # 获取id为l1的class属性值 c1 = tree.xpath('//ul/li[@id="l1"]/@class') print(c1) # ['class1'] # 获取id中包含l的标签 li_list = tree.xpath('//ul/li[contains(@id, "l")]/text()') print(li_list) # ['北京', '上海'] # 获取id以d开头的标签 li_list = tree.xpath('//ul/li[starts-with(@id,"d")]/text()') print(li_list) # ['广州'] # 获取id为l2并且class为class2的标签 li_list = tree.xpath('//ul/li[@id="l2" and @class="class2"]/text()') print(li_list) # ['上海'] # 获取id为l2或id为d1的标签 li_list = tree.xpath('//ul/li[@id="l2"]/text() | //ul/li[@id="d1"]/text()') print(li_list) # ['上海', '广州']

import urllib.request from lxml import etree url = 'http://www.baidu.com' headers = { 'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36' } request = urllib.request.Request(url=url, headers=headers) response = urllib.request.urlopen(request) content = response.read().decode('utf-8') tree = etree.HTML(content) value = tree.xpath('//input[@id="su"]/@value') print(value)

# 需求 下载的前十页的图片 # https://sc.chinaz.com/tupian/qinglvtupian.html 1 # https://sc.chinaz.com/tupian/qinglvtupian_page.html import urllib.request from lxml import etree def create_request(page): if (page == 1): url = 'https://sc.chinaz.com/tupian/qinglvtupian.html' else: url = 'https://sc.chinaz.com/tupian/qinglvtupian_' + str(page) + '.html' headers = { 'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36', } request = urllib.request.Request(url=url, headers=headers) return request def get_content(request): response = urllib.request.urlopen(request) content = response.read().decode('utf-8') return content def down_load(content): # 下载图片 # urllib.request.urlretrieve('图片地址','文件的名字') tree = etree.HTML(content) name_list = tree.xpath('//div[@id="container"]//a/img/@alt') # 一般设计图片的网站都会进行懒加载 src_list = tree.xpath('//div[@id="container"]//a/img/@src2') print(src_list) for i in range(len(name_list)): name = name_list[i] src = src_list[i] url = 'https:' + src urllib.request.urlretrieve(url=url, filename='./loveImg/' + name + '.jpg') if __name__ == '__main__': start_page = int(input('请输入起始页码')) end_page = int(input('请输入结束页码')) for page in range(start_page, end_page + 1): # (1) 请求对象的定制 request = create_request(page) # （2）获取网页的源码 content = get_content(request) # （3）下载 down_load(content)

pip install jsonpath 

obj = json.load(open('json文件', 'r', encoding='utf‐8')) ret = jsonpath.jsonpath(obj, 'jsonpath语法') 

{ "store": { "book": [ { "category": "修真", "author": "六道", "title": "坏蛋是怎样练成的", "price": 8.95 }, { "category": "修真", "author": "天蚕土豆", "title": "斗破苍穹", "price": 12.99 }, { "category": "修真", "author": "唐家三少", "title": "斗罗大陆", "isbn": "0-553-21311-3", "price": 8.99 }, { "category": "修真", "author": "南派三叔", "title": "星辰变", "isbn": "0-395-19395-8", "price": 22.99 } ], "bicycle": { "author": "老马", "color": "黑色", "price": 19.95 } } }

import json import jsonpath obj = json.load(open('jsonpath.json', 'r', encoding='utf-8')) # 书店所有书的作者 author_list = jsonpath.jsonpath(obj, '$.store.book[*].author') print(author_list) # ['六道', '天蚕土豆', '唐家三少', '南派三叔'] # 所有的作者 author_list = jsonpath.jsonpath(obj, '$..author') print(author_list) # ['六道', '天蚕土豆', '唐家三少', '南派三叔', '老马'] # store下面的所有的元素 tag_list = jsonpath.jsonpath(obj, '$.store.*') print( tag_list) # [[{'category': '修真', 'author': '六道', 'title': '坏蛋是怎样练成的', 'price': 8.95}, {'category': '修真', 'author': '天蚕土豆', 'title': '斗破苍穹', 'price': 12.99}, {'category': '修真', 'author': '唐家三少', 'title': '斗罗大陆', 'isbn': '0-553-21311-3', 'price': 8.99}, {'category': '修真', 'author': '南派三叔', 'title': '星辰变', 'isbn': '0-395-19395-8', 'price': 22.99}], {'author': '老马', 'color': '黑色', 'price': 19.95}] # store里面所有东西的price price_list = jsonpath.jsonpath(obj, '$.store..price') print(price_list) # [8.95, 12.99, 8.99, 22.99, 19.95] # 第三个书 book = jsonpath.jsonpath(obj, '$..book[2]') print(book) # [{'category': '修真', 'author': '唐家三少', 'title': '斗罗大陆', 'isbn': '0-553-21311-3', 'price': 8.99}] # 最后一本书 book = jsonpath.jsonpath(obj, '$..book[(@.length-1)]') print(book) # [{'category': '修真', 'author': '南派三叔', 'title': '星辰变', 'isbn': '0-395-19395-8', 'price': 22.99}] # 前面的两本书 book_list = jsonpath.jsonpath(obj, '$..book[0,1]') # book_list = jsonpath.jsonpath(obj,'$..book[:2]') print( book_list) # [{'category': '修真', 'author': '六道', 'title': '坏蛋是怎样练成的', 'price': 8.95}, {'category': '修真', 'author': '天蚕土豆', 'title': '斗破苍穹', 'price': 12.99}] # 条件过滤需要在（）的前面添加一个？ # 过滤出所有的包含isbn的书。 book_list = jsonpath.jsonpath(obj, '$..book[?(@.isbn)]') print( book_list) # [{'category': '修真', 'author': '唐家三少', 'title': '斗罗大陆', 'isbn': '0-553-21311-3', 'price': 8.99}, {'category': '修真', 'author': '南派三叔', 'title': '星辰变', 'isbn': '0-395-19395-8', 'price': 22.99}] # 哪本书超过了10块钱 book_list = jsonpath.jsonpath(obj, '$..book[?(@.price>10)]') print( book_list) # [{'category': '修真', 'author': '天蚕土豆', 'title': '斗破苍穹', 'price': 12.99}, {'category': '修真', 'author': '南派三叔', 'title': '星辰变', 'isbn': '0-395-19395-8', 'price': 22.99}]

1.根据标签名查找节点 soup.a 【注】只能找到第一个a soup.a.name soup.a.attrs 2.函数 (1).find(返回一个对象) find('a')：只找到第一个a标签 find('a', title='名字') find('a', class_='名字') (2).find_all(返回一个列表) find_all('a') 查找到所有的a find_all(['a', 'span']) 返回所有的a和span find_all('a', limit=2) 只找前两个a (3).select(根据选择器得到节点对象)【推荐】 1.element eg:p 2..class eg:.firstname 3.#id eg:#firstname 4.属性选择器 [attribute] eg:li = soup.select('li[class]') [attribute=value] eg:li = soup.select('li[class
                
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