python爬虫--用xpath爬豆瓣电影

步骤

将目标网站下的页面抓取下来
将抓取下来的数据根据一定规则进行提取

具体流程

将目标网站下的页面抓取下来

1. 倒库

import requests

2.头信息（有时候可不写）

headers = {
    #请求身份/默认为User-Agent:python
	'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.87 Safari/537.36',
    'Referer': 'https://movie.douban.com/'
}

3.url

url = 'https://movie.douban.com/cinema/nowplaying/zhengzhou/'

4.返回响应

response = requests.get(url,headers=headers)  #响应
#print(response.text)
text = response.text

response.text:返回的是一个经过解码后的字符串，是str（unicode）类型

response.concent:返回的是一个原生的字符串，就是从网页上抓取下来的，没有经过解码的字符串，是bytes类型

2.将抓取下来的数据根据一定规则进行提取

1.将爬取下来是数据用lxml进行解析

from lxml import etree
html = etree.HTML(text)

2.获取ul、li下的 'title'、'score'、'poster'

先看看框架

ul (class='list')

li ······

a ······

ul = html.xpath("//ul[@class='lists']")[0]
#print(etree.tostring(ul,encoding='utf-8').decode('utf-8'))
lis = ul.xpath('./li')
for li in lis:
    #print(etree.tostring(li,encoding='utf-8').decode('utf-8'))
    title = li.xpath('@data-title')[0]
    #print(title)
    score = li.xpath('@data-score')[0]
    # print(score)
    poster = li.xpath('.//img/@src')[0]
   # print(poster)

[0] 只获取第一个内容

// 获取网页当中所有的元素

./ 在当前标签下获取

.// 在当前标签下下获取

xpath返回的是列表的形式 ['']，[0]就可以只拿内容

3.储存信息

1.下载

request.urlretrieve(poster, 'D:/A/' + score + title + '.jpg')

下载到D盘下A目录中，文件名为评分+影名.jpg

2.显示进度条

fns_num = 1
num = len(lis)
for li in lis:
    ···
    print("\r完成进度: {:.2f}%".format(fns_num * 100 / num), end="")
    fns_num += 1

完整代码

#coding=UTF-8

import requests
from lxml import etree
from urllib import request

headers = {
	'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.87 Safari/537.36',
	'Referer': 'https://movie.douban.com/'
}
url = 'https://movie.douban.com/cinema/nowplaying/zhengzhou/'
response = requests.get(url,headers=headers)
# print(response.text)
text = response.text

html = etree.HTML(text)
ul = html.xpath("//ul[@class='lists']")[0]
# print(etree.tostring(ul,encoding='utf-8').decode('utf-8'))
lis = ul.xpath("./li")
# movies = []
fns_num = 1
num = len(lis)
for li in lis:
    # print(etree.tostring(li,encoding='utf-8').decode('utf-8'))
    title = li.xpath('@data-title')[0]
    # print(title)
    score = li.xpath('@data-score')[0]
    # print(score)
    poster = li.xpath('.//img/@src')[0]
    # print(poster)

    request.urlretrieve(poster, 'D:/A/' + score + title + '.jpg')
    print("\r完成进度: {:.2f}%".format(fns_num * 100 / num), end="")
    fns_num += 1