编写多线程爬虫(线程数量至少4个，使用xpth)爬取杂文标签下 所有书籍(至少爬取前10页)的信息(包括书名、作者、出版社、出版 日期、页数、价格、ISBN号、豆瓣评分、评价人数、书籍封面、 URL)，并按照豆瓣评分降序保存(以标签名称命名)

好的，我会为您解答这个问题。首先我们需要了解一下Python的多线程爬虫基本原理。

Python的多线程爬虫的基本流程如下：

1. 创建一个线程池，线程数量至少为4个。

2. 将任务分配给线程池中的线程。

3. 每个线程拥有自己的爬虫实例，可以独立地爬取网页。

4. 爬取到的数据需要保存到本地或者数据库中。

接下来，我们可以根据这个流程来实现代码。具体实现步骤如下：

1. 导入必要的库

import requests
from lxml import etree
import threading
import os
import csv

2. 定义爬虫函数

def spider(start_page, end_page):
    url = 'https://book.douban.com/tag/%E6%9D%82%E6%96%87?start={}&type=T'
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3'}
    for i in range(start_page, end_page):
        url_ = url.format(i * 20)
        response = requests.get(url_, headers=headers)
        html = etree.HTML(response.text)
        items = html.xpath('//li[@class="subject-item"]')
        for item in items:
            book_title = item.xpath('.//h2/a/text()')[0]
            book_url = item.xpath('.//h2/a/@href')[0]
            book_info = item.xpath('.//div[@class="pub"]/text()')[0]
            book_rate = item.xpath('.//span[@class="rating_nums"]/text()')[0]
            book_people = item.xpath('.//span[@class="pl"]/text()')[0]
            book_cover = item.xpath('.//img/@src')[0]
            book_info_list = book_info.split('/')
            book_author = book_info_list[0]
            book_publisher = book_info_list[-3]
            book_date = book_info_list[-2]
            book_pages = book_info_list[-4]
            book_price = book_info_list[-1]
            book_isbn = item.xpath('.//div[@class="star clearfix"]/span[3]/text()')[0]
            with open('book.csv', 'a', newline='', encoding='utf-8-sig') as f:
                writer = csv.writer(f)
                writer.writerow([book_title, book_author, book_publisher, book_date, book_pages, book_price, book_isbn, book_rate, book_people, book_cover, book_url])

3. 定义线程函数

def thread_func(start_page, end_page):
    spider(start_page, end_page)

4. 将任务分配给线程池中的线程

threads = []
for i in range(0, 10, 2):
    t = threading.Thread(target=thread_func, args=(i, i+2))
    threads.append(t)

for t in threads:
    t.start()

for t in threads:
    t.join()

5. 对爬取到的数据按照豆瓣评分降序保存

import pandas as pd
df = pd.read_csv('book.csv', header=None, names=['book_title', 'book_author', 'book_publisher', 'book_date', 'book_pages', 'book_price', 'book_isbn', 'book_rate', 'book_people', 'book_cover', 'book_url'], encoding='utf-8')
df_sorted = df.sort_values(by=['book_rate'], ascending=False)
df_sorted.to_csv('杂文.csv', index=False, encoding='utf-8-sig')
os.remove('book.csv')

完整代码如下：