Python xpath,JsonPath,bs4的基本使用_Python

1.xpath
- 1.1 xpath使用
- 1.2 xpath基本语法
- 1.3 示例
- 1.4 爬取百度搜索按钮的value
2. JsonPath
- 2.1 pip安装
- 2.2 jsonpath的使用
3. BeautifulSoup
- 3.1 基本简介
- 3.2 安装以及创建
- 3.3 节点定位
- 3.5 节点信息
- 3.6 使用示例
- 3.7 解析星巴克产品名称

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/h1/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"]

1.4 爬取百度搜索按钮的value

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)

Python xpath,JsonPath,bs4的基本使用

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.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)

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的基本使用

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 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}]

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",    <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="" 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", # <a href="" 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="" 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="" 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="" 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li
print(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="" 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)  # None
print(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.request
url = "https://www.starbucks.com.cn/menu/"
response = urllib.request.urlopen(url)
content = response.read().decode("utf-8")
from bs4 import BeautifulSoup
soup = 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的基本使用