爬虫Scrapy框架学习（四）-中国保险监督委员会爬取案例

本案例使用的框架为CrawlSpider框架，与传统Spider框架相比能够快速的实现页面跳转的功能，且本案例描述了随机替换User-Agent的“反反”爬虫思想，值得读者细心研究。

• 使用scrapy genspider –t crawl cf “circ.gov.cn”创建爬虫

1.项目框架展示

2.项目爬取网页展示

3.cf.py文件

# -*- coding: utf-8 -*-
import scrapy
from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule
import re

#scrapy genspider -t crawl cf circ.gov.cn
class CfSpider(CrawlSpider):
    name = 'cf'
    allowed_domains = ['circ.gov.cn']
    start_urls = ['http://circ.gov.cn/web/site0/tab5240/module14430/page1.htm']

    #定义提取url地址规则(循环执行)---（不需要补充完整的url地址，会自动补充）
    rules = (#连接提取器   follow-当前url地址的响应是否重新经过rules来提取url地址(不写时只执行一次，不断提取下一页时一定要写)
        Rule(LinkExtractor(allow=r'/web/site0/tab5240/info\d+\.htm'), callback='parse_item'),#提取详情页
        # Rule(LinkExtractor(allow=r'/web/site0/tab5240/module14430/page\d+\.htm'), follow=True),#跳转下一页-匹配第一个，一直到无法匹配到下一些URL地址

    )

    #parse函数有特殊功能，不能定义
    def parse_item(self, response):
        item = {}
        item["title"] = re.findall("<!--TitleStart-->(.*?)<!--TitleEnd-->", response.body.decode())[0]
        item["publish_date"] = re.findall("发布时间：(20\d{2}-\d{2}-\d{2})", response.body.decode())[0]
        print(item)

4.middlewares.py文件（实现随机设置User-Agent）

# -*- coding: utf-8 -*-

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

class RandomUserAgentMiddlewares:#下载中间件，每次请求都会用他
    def process_request(self, request, spider):
        ua = random.choice(spider.settings.get("USER_AGENTS_LIST"))
        print("执行到这里")
        request.headers["User-Agent"] = ua

class CheckUserAgent:#检查请求头的user—agent是否不同
    def process_response(self, request, response,  spider):
        # print(dir(response.request))
        print(request.headers["User-Agent"])
        return response

5.settings.py文件

# -*- coding: utf-8 -*-

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

BOT_NAME = 'circ'

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


# Crawl responsibly by identifying yourself (and your website) on the user-agent
USER_AGENT = 'Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36'

# Obey robots.txt rules

ROBOTSTXT_OBEY = False

LOG_LEVEL = "WARNING"
# 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://doc.scrapy.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
#DOWNLOAD_DELAY = 3
# 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',
#}

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

# Enable or disable downloader middlewares
# See https://doc.scrapy.org/en/latest/topics/downloader-middleware.html
DOWNLOADER_MIDDLEWARES = {
    'circ.middlewares.RandomUserAgentMiddlewares': 543,
    'circ.middlewares.CheckUserAgent':544
}

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

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

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://doc.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://doc.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'
USER_AGENTS_LIST = [ "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 2.0.50727; Media Center PC 6.0)", "Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 1.0.3705; .NET CLR 1.1.4322)", "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.30)", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 (KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)", "Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6", "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0", "Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5" ]

• ROBOTSTXT_OBEY设置为False
• LOG_LEVEL = “WARNING”
• 不要忘记打开下载中间件（每次请求都会先经过下载中间件）DOWNLOADER_MIDDLEWARES
• 准备一个有多个User-Agent的列表USER_AGENTS_LIST

6.结果展示

• 输出了相应的爬取内容和当前User-Agent的设置值。