解析数据(正则,xpath)

正则表达式拆分

import re

# 1.拆分字符串

one = 'asdsfsgsh'

# 标准 是 s 为拆分

pattern = re.compile('s')

result = pattern.split(one)

# print(result)

# 2.匹配中文

two = '<a href="https://www.baidu.com/" nslog="normal" nslog-type="10600112" data-href="https://www.baidu.com/s?ie=utf-8&amp;fr=bks0000&amp;wd=">网页是最新版本的,适配移动端</a>'

# python中 匹配中问 [a-z] unicode的范围 * + ?

pattern = re.compile('[\u4e00-\u9fa5]+')

result = pattern.findall(two)

print(result)

import re

import requests

url = 'http://news.baidu.com/'

headers = {

    "User-Agent": 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36'

}

# response.text 不太准确 转码 是靠推测

data = requests.get(url, headers=headers).content.decode()

# 正则解析 数据

#  每个新闻的titile, url

# <a href="http://news.cnr.cn/native/gd/20181028/t20181028_524397644.shtml" target="_blank" mon="r=1">民营经济再吃定心丸,民企当体会怎样深意</a>

pattern = re.compile('<a href="(.*?)" target="_blank" mon="(.*?)">(.*?)</a>')

# pattern = re.compile('<a (.*?)</a>',re.S)

result = pattern.findall(data)

print(result)

# with open('02news.html', 'w') as f:

#     f.write(data)

xpath解析

import re

import requests

# 安装支持 解析html和XML的解析库 lxml

# pip install lxml

from lxml import etree

url = 'http://news.baidu.com/'

headers = {

    "User-Agent": 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36'

}

# response.text 不太准确 转码 是靠推测

data = requests.get(url, headers=headers).content.decode()

# 1.转解析类型

xpath_data = etree.HTML(data)

# xpath 语法 1. 节点 /

#            2. 跨节点: //

#            3. 精确的标签: //a[@属性="属性值"]

#            4. 标签包裹的内容 text()

#            5. 属性:@href

#              xpath--s数据类型---list

# 2调用 xpath的方法

result = xpath_data.xpath('/html/head/title//text()')

result = xpath_data.xpath('//a/text()')

result = xpath_data.xpath('//a[@mon="ct=1&a=2&c=top&pn=18"]/text()')

result = xpath_data.xpath('//a[@mon="ct=1&a=2&c=top&pn=18"]/@href')

result = xpath_data.xpath('//li/a/text()')

print(result)

# with open('02news.html', 'w') as f:

#     f.write(data)

注意事项

from  lxml import etree

html = """

    <html>

    <body>

    <ul>

     <li>1

         <a href="">子</a>

     </li>

     <li>2

        <a href="">子</a>

     </li>

     <li>3

        <a href="">子</a>

     </li>

     <li>4

         <a href="">子</a>

     </li>

     <li>5

        <a href="">子</a>

     </li>

 </ul>

 </body>

 </html>

"""

# 1.转类型

x_data = etree.HTML(html)

# 2.xpath 下标 是从 1开始; 只能取 平级关系的标签

result = x_data.xpath('//li[5]/text()')

result = x_data.xpath('/html/body/ul/li/a/text()')

result = x_data.xpath('//a[2]')

print(result)

拆分实例

import requests

from lxml import etree

import json

class BtcSpider(object):

    def __init__(self):

        self.base_url = 'http://8btc.com/forum-61-'

        self.headers = {

            "User-Agent": 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36'

        }

        self.data_list = []

    # 1.发请求

    def get_response(self, url):

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

        # 网页的 编码到底 是 gbk 还是 urf-8  head--meta-charset=""

        # 原因 是 抓取 网页的 编码 就是 gbk的 所以 解码的时候 也是要gbk

        # data = response.content.decode('gbk')

        data = response.content

        return data

    # 2.解析数据

    def parse_data(self, data):

        # 使用xpath 解析当前页面 所有的 新闻title 和url 保存

        # 1.转类型

        x_data = etree.HTML(data)

        # 2.根据xpath路径解析

        # 路径 1. 纯手写  2. 借助浏览器的 右击 粘贴xpath路径; 需要修改

        title_list = x_data.xpath('//a[@class="s xst"]/text()')

        # title_list = x_data.xpath('//form[@id="moderate"]/div/div[2]/div/a[@class="s xst"]/text()')

        url_list = x_data.xpath('//a[@class="s xst"]/@href')

        for index, title in enumerate(title_list):

            news = {}

            # print(index)

            # print(title)

            news['name'] = title

            news['url'] = url_list[index]

            self.data_list.append(news)

    # 3.保存数据

    def save_data(self):

        # 将 list---str

        data_str = json.dumps(self.data_list)

        with open('05btc.json', 'w') as f:

            f.write(data_str)

    # 4.启动

    def run(self):

        for i in range(1, 5):

            # 1.拼接 完整url

            url = self.base_url + str(i) + '.html'

            print(url)

            # 2.发请求

            data = self.get_response(url)

            # 3.做解析

            self.parse_data(data)

        # 4.保存

        self.save_data()

BtcSpider().run()

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解析数据(正则,xpath)

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