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How to use Python for xpath, JsonPath, and bs4?

时间：2023-05-10 10:00

1.xpath

1.1 xpath使用

google提前安装xpath插件，按ctrl + shift + x 出现小黑框
安装lxml库 pip install lxml ‐i https://pypi.douban.com/simple
导入lxml.etreefrom lxml import etree
etree.parse() 解析本地文件html_tree = etree.parse('XX.html')
etree.HTML() 服务器响应文件html_tree = etree.HTML(response.read().decode('utf‐8')
.html_tree.xpath(xpath路径)

1.2 xpath基本语法

1.路径查询

查找所有子孙节点，不考虑层级关系
找直接子节点

2.谓词查询

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

3.属性查询

//@class

4.模糊查询

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

5.内容查询

//div/h2/text()

6.逻辑运算

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

1.3 示例

xpath.html

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8"/>    <title>Title</title></head><body>    <ul>        <li id="l1" class="class1">北京</li>        <li id="l2" class="class2">上海</li>        <li id="d1">广州</li>        <li>深圳</li>    </ul></body></html>

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lili_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lili_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']

1.4 爬取百度搜索按钮的value

import urllib.requestfrom lxml import etreeurl = '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)

Python xpath,JsonPath,bs4怎么使用

1.5 爬取站长素材的图片

# 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.htmlimport urllib.requestfrom lxml import etreedef 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 requestdef get_content(request):    response = urllib.request.urlopen(request)    content = response.read().decode('utf-8')    return contentdef 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)

2. JsonPath

2.1 pip安装

pip install jsonpath

2.2 jsonpath的使用

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

JSONPath语法元素和对应XPath元素的对比：

Python xpath,JsonPath,bs4怎么使用

示例：

jsonpath.json

{ "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 jsonimport jsonpathobj = 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, '$.store.*')print(    tag_list)  # [[{'category': '修真', 'author': '六道', 'title': '坏蛋是怎样练成的', 'price': 8.95}, {'category': '修真', 'author': '天蚕土豆', 'title': '斗破苍穹', 'price': 12.99}, {'category': '修真', 'author': '唐家三少', 'title': '斗罗大陆', 'isbn': '0-553-21311-3', 'price': 8.99}, {'category': '修真', 'author': '南派三叔', 'title': '星辰变', 'isbn': '0-395-19395-8', 'price': 22.99}], {'author': '老马', 'color': '黑色', 'price': 19.95}]# store里面所有东西的priceprice_list = jsonpath.jsonpath(obj, '$.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}]

3. BeautifulSoup

3.1 基本简介

1.安装

pip install bs4

2.导入

from bs4 import BeautifulSoup

3.创建对象

服务器响应的文件生成对象 soup = BeautifulSoup(response.read().decode(), 'lxml')
本地文件生成对象 soup = BeautifulSoup(open('1.html'), 'lxml')

注意：默认打开文件的编码格式gbk所以需要指定打开编码格式utf-8

3.2 安装以及创建

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="hengheng1"]') 		5.层级选择器 			element element 				div p 			element>element 				div>p 			element,element 				div,p 					eg:soup = soup.select('a,span')

3.3 节点定位

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="hengheng1"]') 		5.层级选择器 			element element 				div p 			element>element 				div>p 			element,element 				div,p 					eg:soup = soup.select('a,span')

3.5 节点信息

(1).获取节点内容：适用于标签中嵌套标签的结构 	obj.string 	obj.get_text()【推荐】 (2).节点的属性 	tag.name 获取标签名 		eg:tag = find('li) 			print(tag.name) 	tag.attrs将属性值作为一个字典返回 (3).获取节点属性 	obj.attrs.get('title')【常用】 	obj.get('title') 	obj['title']

(1).获取节点内容：适用于标签中嵌套标签的结构 	obj.string 	obj.get_text()【推荐】 (2).节点的属性 	tag.name 获取标签名 		eg:tag = find('li) 			print(tag.name) 	tag.attrs将属性值作为一个字典返回 (3).获取节点属性 	obj.attrs.get('title')【常用】 	obj.get('title') 	obj['title']

3.6 使用示例

bs4.html

<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title>Title</title></head><body>    <div>        <ul>            <li id="l1">张三</li>            <li id="l2">李四</li>            <li>王五</li>            <a href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" " class="a1">google</a>            <span>嘿嘿嘿</span>        </ul>    </div>    <a href="" title=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" a2">百度</a>    <div id="d1">        <span>            哈哈哈        </span>    </div>    <p id="p1" class="p1">呵呵呵</p></body></html>

from bs4 import BeautifulSoup# 通过解析本地文件 来将bs4的基础语法进行讲解# 默认打开的文件的编码格式是gbk 所以在打开文件的时候需要指定编码soup = BeautifulSoup(open('bs4.html', encoding='utf-8'), 'lxml')# 根据标签名查找节点# 找到的是第一个符合条件的数据print(soup.a)  # <a class="a1" href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ">google</a># 获取标签的属性和属性值print(soup.a.attrs)  # {'href': '', 'id': '', 'class': ['a1']}# bs4的一些函数# （1）find# 返回的是第一个符合条件的数据print(soup.find('a'))  # <a class="a1" href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ">google</a># 根据title的值来找到对应的标签对象print(soup.find('a', title="a2"))  # <a href="" title=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" a2">百度</a># 根据class的值来找到对应的标签对象  注意的是class需要添加下划线print(soup.find('a', class_="a1"))  # <a class="a1" href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ">google</a># （2）find_all  返回的是一个列表 并且返回了所有的a标签print(soup.find_all('a'))  # [<a class="a1" href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ">google</a>, <a href="" title=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" a2">百度</a>]# 如果想获取的是多个标签的数据 那么需要在find_all的参数中添加的是列表的数据print(soup.find_all(['a','span']))  # [<a class="a1" href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ">google</a>, <span>嘿嘿嘿</span>, <a href="" title=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" a2">百</a><spa哈</span>]# limit的作用是查找前几个数据print(soup.find_all('li', limit=2))  # [<li id="l1">张三</li>, <li id="l2">李四</li>]# （3）select（推荐）# select方法返回的是一个列表  并且会返回多个数据print(soup.select('a'))  # [<a class="a1" href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ">google</a>, <a href="" title=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" a2">百度</a>]# 可以通过.代表class  我们把这种操作叫做类选择器print(soup.select('.a1'))  # [<a class="a1" href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ">google</a>]print(soup.select('#l1'))  # [<li id="l1">张三</li>]# 属性选择器---通过属性来寻找对应的标签# 查找到li标签中有id的标签print(soup.select('li[id]'))  # [<li id="l1">张三</li>, <li id="l2">李四</li>]# 查找到li标签中id为l2的标签print(soup.select('li[id="l2"]'))  # [<li id="l2">李四</li>]# 层级选择器#  后代选择器# 找到的是div下面的liprint(soup.select('div li'))  # [<li id="l1">张三</li>, <li id="l2">李四</li>, <li>王五</li>]# 子代选择器#  某标签的第一级子标签# 注意：很多的计算机编程语言中 如果不加空格不会输出内容  但是在bs4中 不会报错 会显示内容print(soup.select('div > ul > li'))  # [<li id="l1">张三</li>, <li id="l2">李四</li>, <li>王五</li>]# 找到a标签和li标签的所有的对象print(soup.select(    'a,li'))  # [<li id="l1">张三</li>, <li id="l2">李四</li>, <li>王五</li>, <a class="a1" href="" id=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ">google</a>, <a href="" title=" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" a2">百度</a>]# 节点信息#    获取节点内容obj = soup.select('#d1')[0]# 如果标签对象中 只有内容 那么string和get_text()都可以使用# 如果标签对象中 除了内容还有标签 那么string就获取不到数据 而get_text()是可以获取数据# 我们一般情况下  推荐使用get_text()print(obj.string)  # Noneprint(obj.get_text())  # 哈哈哈# 节点的属性obj = soup.select('#p1')[0]# name是标签的名字print(obj.name)  # p# 将属性值左右一个字典返回print(obj.attrs)  # {'id': 'p1', 'class': ['p1']}# 获取节点的属性obj = soup.select('#p1')[0]#print(obj.attrs.get('class'))  # ['p1']print(obj.get('class'))  # ['p1']print(obj['class'])  # ['p1']

3.7 解析星巴克产品名称

import urllib.requesturl = 'https://www.starbucks.com.cn/menu/'response = urllib.request.urlopen(url)content = response.read().decode('utf-8')from bs4 import BeautifulSoupsoup = BeautifulSoup(content,'lxml')# //ul[@class="grid padded-3 product"]//strong/text()# 一般先用xpath方式通过google插件写好解析的表达式name_list = soup.select('ul[class="grid padded-3 product"] strong')for name in name_list:    print(name.get_text())

Python xpath,JsonPath,bs4怎么使用