Python 详解通过Scrapy框架实现爬取CSDN全站热榜标题热词流程

目录

• 前言
• 环境部署
• 实现过程
• 创建项目
• 定义Item实体
• 关键词提取工具
• 爬虫构造
• 中间件代码构造
• 制作自定义pipeline
• settings配置
• 执行主程序
• 执行结果
• 总结

前言

接着我的上一篇：Python 详解爬取并统计CSDN全站热榜标题关键词词频流程

我换成Scrapy架构也实现了一遍。获取页面源码底层原理是一样的，Scrapy架构更系统一些。下面我会把需要注意的问题，也说明一下。

提供一下GitHub仓库地址：github本项目地址

环境部署

scrapy安装

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

selenium安装

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

jieba安装

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

IDE：PyCharm

google chrome driver下载对应版本：google chrome driver下载地址

检查浏览器版本，下载对应版本。

实现过程

下面开始搞起。

创建项目

使用scrapy命令创建我们的项目。

scrapy startproject csdn_hot_words

项目结构，如同官方给出的结构。

定义Item实体

按照之前的逻辑，主要属性为标题关键词对应出现次数的字典。代码如下：

# 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()

关键词提取工具

使用jieba分词获取工具。

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time    : 2021/11/5 23:47
# @Author  : 至尊宝
# @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

爬虫构造

这里需要给爬虫初始化一个浏览器参数，用来实现页面的动态加载。

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time    : 2021/11/5 23:47
# @Author  : 至尊宝
# @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')  # 使用无头谷歌浏览器模式
        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

代码说明

1、这里使用的是chrome的无头模式，就不需要有个浏览器打开再访问，都是后台执行的。

2、需要添加chromedriver的执行文件地址。

3、在parse的部分，可以参考之前我文章的xpath，获取到标题并且调用关键词提取，构造item对象。

中间件代码构造

添加js代码执行内容。中间件完整代码：

# 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('超时异常:{}'.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)

制作自定义pipeline

定义按照词频统计最终结果输出到文件。代码如下：

# 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

配置上要做一些调整。如下调整：

# 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'

执行主程序

可以通过scrapy的命令执行，但是为了看日志方便，加了一个主程序代码。

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

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

执行结果

执行部分日志

得到result.txt结果。

总结

看，java还是yyds。不知道为什么2021这个关键词也可以排名靠前。于是我觉着把我标题也加上2021。

GitHub项目地址在发一遍：github本项目地址

申明一下，本文案例仅研究探索使用，不是为了恶意攻击。

分享：

凡夫俗子不下苦功夫、死力气去努力做成一件事，根本就没资格去谈什么天赋不天赋。

——烽火戏诸侯《剑来》

如果本文对你有用的话，请不要吝啬你的赞，谢谢。

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