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前言

我換成Scrapy架構也實現了一遍。獲取頁面源碼底層原理是一樣的，Scrapy架構更系統一些。下面我會把需要注意的問題，也說明一下。

提供一下GitHub倉庫地址：github本項目地址

環境部署

scrapy安裝

pip install scrapy -i https://pypi.douban.com/simple

selenium安裝

pip install selenium -i https://pypi.douban.com/simple

jieba安裝

pip install jieba -i https://pypi.douban.com/simple

IDE：PyCharm

google chrome driver下載對應版本：google chrome driver下載地址

檢查瀏覽器版本，下載對應版本。

Python 詳解通過Scrapy框架實現爬取CSDN全站熱榜標題熱詞流程

實現過程

下面開始搞起。

創建項目

使用scrapy命令創建我們的項目。

scrapy startproject csdn_hot_words

項目結構，如同官方給出的結構。

Python 詳解通過Scrapy框架實現爬取CSDN全站熱榜標題熱詞流程

定義Item實體

按照之前的邏輯，主要屬性為標題關鍵詞對應出現次數的字典。代碼如下：

# Define here the models for your scraped items
#
# See documentation in:
# https://docs.scrapy.org/en/latest/topics/items.html

import scrapy


class CsdnHotWordsItem(scrapy.Item):
  # define the fields for your item here like:
  # name = scrapy.Field()
  words = scrapy.Field()

關鍵詞提取工具

使用jieba分詞獲取工具。

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time    : 2021/11/5 23:47
# @Author  : 至尊寶
# @Site    : 
# @File    : analyse_sentence.py

import jieba.analyse


def get_key_word(sentence):
  result_dic = {}
  words_lis = jieba.analyse.extract_tags(
      sentence, topK=3, withWeight=True, allowPOS=())
  for word, flag in words_lis:
      if word in result_dic:
          result_dic[word] += 1
      else:
          result_dic[word] = 1
  return result_dic

爬蟲構造

這里需要給爬蟲初始化一個瀏覽器參數，用來實現頁面的動態加載。

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time    : 2021/11/5 23:47
# @Author  : 至尊寶
# @Site    : 
# @File    : csdn.py

import scrapy
from selenium import webdriver
from selenium.webdriver.chrome.options import Options

from csdn_hot_words.items import CsdnHotWordsItem
from csdn_hot_words.tools.analyse_sentence import get_key_word


class CsdnSpider(scrapy.Spider):
  name = 'csdn'
  # allowed_domains = ['blog.csdn.net']
  start_urls = ['https://blog.csdn.net/rank/list']

  def __init__(self):
      chrome_options = Options()
      chrome_options.add_argument('--headless')  # 使用無頭谷歌瀏覽器模式
      chrome_options.add_argument('--disable-gpu')
      chrome_options.add_argument('--no-sandbox')
      self.browser = webdriver.Chrome(chrome_options=chrome_options,
                                      executable_path="E:\\chromedriver_win32\\chromedriver.exe")
      self.browser.set_page_load_timeout(30)

  def parse(self, response, **kwargs):
      titles = response.xpath("//div[@class='hosetitem-title']/a/text()")
      for x in titles:
          item = CsdnHotWordsItem()
          item['words'] = get_key_word(x.get())
          yield item

代碼說明

1、這里使用的是chrome的無頭模式，就不需要有個瀏覽器打開再訪問，都是后臺執行的。

2、需要添加chromedriver的執行文件地址。

3、在parse的部分，可以參考之前我文章的xpath，獲取到標題并且調用關鍵詞提取，構造item對象。

中間件代碼構造

添加js代碼執行內容。中間件完整代碼：

# Define here the models for your spider middleware
#
# See documentation in:
# https://docs.scrapy.org/en/latest/topics/spider-middleware.html

from scrapy import signals
from scrapy.http import HtmlResponse
from selenium.common.exceptions import TimeoutException
import time

from selenium.webdriver.chrome.options import Options

# useful for handling different item types with a single interface
from itemadapter import is_item, ItemAdapter


class CsdnHotWordsSpiderMiddleware:
  # Not all methods need to be defined. If a method is not defined,
  # scrapy acts as if the spider middleware does not modify the
  # passed objects.

  @classmethod
  def from_crawler(cls, crawler):
      # This method is used by Scrapy to create your spiders.
      s = cls()
      crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
      return s

  def process_spider_input(self, response, spider):
      # Called for each response that goes through the spider
      # middleware and into the spider.

      # Should return None or raise an exception.
      return None

  def process_spider_output(self, response, result, spider):
      # Called with the results returned from the Spider, after
      # it has processed the response.

      # Must return an iterable of Request, or item objects.
      for i in result:
          yield i

  def process_spider_exception(self, response, exception, spider):
      # Called when a spider or process_spider_input() method
      # (from other spider middleware) raises an exception.

      # Should return either None or an iterable of Request or item objects.
      pass

  def process_start_requests(self, start_requests, spider):
      # Called with the start requests of the spider, and works
      # similarly to the process_spider_output() method, except
      # that it doesn't have a response associated.

      # Must return only requests (not items).
      for r in start_requests:
          yield r

  def spider_opened(self, spider):
      spider.logger.info('Spider opened: %s' % spider.name)


class CsdnHotWordsDownloaderMiddleware:
  # Not all methods need to be defined. If a method is not defined,
  # scrapy acts as if the downloader middleware does not modify the
  # passed objects.

  @classmethod
  def from_crawler(cls, crawler):
      # This method is used by Scrapy to create your spiders.
      s = cls()
      crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
      return s

  def process_request(self, request, spider):
      js = '''
                      let height = 0
              let interval = setInterval(() => {
                  window.scrollTo({
                      top: height,
                      behavior: "smooth"
                  });
                  height += 500
              }, 500);
              setTimeout(() => {
                  clearInterval(interval)
              }, 20000);
          '''
      try:
          spider.browser.get(request.url)
          spider.browser.execute_script(js)
          time.sleep(20)
          return HtmlResponse(url=spider.browser.current_url, body=spider.browser.page_source,
                              encoding="utf-8", request=request)
      except TimeoutException as e:
          print('超時異常:{}'.format(e))
          spider.browser.execute_script('window.stop()')
      finally:
          spider.browser.close()

  def process_response(self, request, response, spider):
      # Called with the response returned from the downloader.

      # Must either;
      # - return a Response object
      # - return a Request object
      # - or raise IgnoreRequest
      return response

  def process_exception(self, request, exception, spider):
      # Called when a download handler or a process_request()
      # (from other downloader middleware) raises an exception.

      # Must either:
      # - return None: continue processing this exception
      # - return a Response object: stops process_exception() chain
      # - return a Request object: stops process_exception() chain
      pass

  def spider_opened(self, spider):
      spider.logger.info('Spider opened: %s' % spider.name)

制作自定義pipeline

定義按照詞頻統計最終結果輸出到文件。代碼如下：

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://docs.scrapy.org/en/latest/topics/item-pipeline.html


# useful for handling different item types with a single interface
from itemadapter import ItemAdapter


class CsdnHotWordsPipeline:

  def __init__(self):
      self.file = open('result.txt', 'w', encoding='utf-8')
      self.all_words = []

  def process_item(self, item, spider):
      self.all_words.append(item)
      return item

  def close_spider(self, spider):
      key_word_dic = {}
      for y in self.all_words:
          print(y)
          for k, v in y['words'].items():
              if k.lower() in key_word_dic:
                  key_word_dic[k.lower()] += v
              else:
                  key_word_dic[k.lower()] = v
      word_count_sort = sorted(key_word_dic.items(),
                               key=lambda x: x[1], reverse=True)
      for word in word_count_sort:
          self.file.write('{},{}\n'.format(word[0], word[1]))
      self.file.close()

settings配置

配置上要做一些調整。如下調整：

# Scrapy settings for csdn_hot_words project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     https://docs.scrapy.org/en/latest/topics/settings.html
#     https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#     https://docs.scrapy.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'csdn_hot_words'

SPIDER_MODULES = ['csdn_hot_words.spiders']
NEWSPIDER_MODULE = 'csdn_hot_words.spiders'

# Crawl responsibly by identifying yourself (and your website) on the user-agent
# USER_AGENT = 'csdn_hot_words (+http://www.yourdomain.com)'
USER_AGENT = 'Mozilla/5.0'

# Obey robots.txt rules
ROBOTSTXT_OBEY = False

# Configure maximum concurrent requests performed by Scrapy (default: 16)
# CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See https://docs.scrapy.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
DOWNLOAD_DELAY = 30
# The download delay setting will honor only one of:
# CONCURRENT_REQUESTS_PER_DOMAIN = 16
# CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
# TELNETCONSOLE_ENABLED = False

# Override the default request headers:
DEFAULT_REQUEST_HEADERS = {
  'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
  'Accept-Language': 'en',
  'User-Agent': 'Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.94 Safari/537.36'
}

# Enable or disable spider middlewares
# See https://docs.scrapy.org/en/latest/topics/spider-middleware.html
SPIDER_MIDDLEWARES = {
 'csdn_hot_words.middlewares.CsdnHotWordsSpiderMiddleware': 543,
}

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
DOWNLOADER_MIDDLEWARES = {
 'csdn_hot_words.middlewares.CsdnHotWordsDownloaderMiddleware': 543,
}

# Enable or disable extensions
# See https://docs.scrapy.org/en/latest/topics/extensions.html
# EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
# }

# Configure item pipelines
# See https://docs.scrapy.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
  'csdn_hot_words.pipelines.CsdnHotWordsPipeline': 300,
}

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/autothrottle.html
# AUTOTHROTTLE_ENABLED = True
# The initial download delay
# AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
# AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
# AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
# AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
# HTTPCACHE_ENABLED = True
# HTTPCACHE_EXPIRATION_SECS = 0
# HTTPCACHE_DIR = 'httpcache'
# HTTPCACHE_IGNORE_HTTP_CODES = []
# HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

執行主程序

可以通過scrapy的命令執行，但是為了看日志方便，加了一個主程序代碼。

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time    : 2021/11/5 22:41
# @Author  : 至尊寶
# @Site    : 
# @File    : main.py
from scrapy import cmdline

cmdline.execute('scrapy crawl csdn'.split())