redis分布式爬虫
概念：多台机器上可以执行同一个爬虫程序,实现网站数据的爬取
原生的scrapy是不可以实现分布式爬虫, 原因如下：
- 调度器无法共享
- 管道无法共享
scrapy-redis组件：专门为scrapy开发的一套组件。 该组件可以让scrapy实现分布式 pip install scrapy-redis
分布式爬取的流程：
1 redis配置文件的配置
- 将 bind 127.0.0.1 进行注释
- 将 protected-mode no 关闭保护模式
2 redis服务器的开启：基于配置文件的开启
3 创建scrapy工程后， 创建基于crawlSpider的爬虫文件
4 导入RedisCrawSpider类 from scrapy_redis.spiders import RedisCrawlSpider
5 将start_url修改成redis_key = ‘xxx‘
6 解析代码编写
7 将项目的管道和调度器配置成基于scrapy-redis组件中
ITEM_PIPELINES = {
‘scrapy_redis.pipelines.RedisPipeline‘: 400
}
# 使用scrapy-redis组件的去重队列
DUPEFILTER_CLASS = "scrapy_redis.dupefilter.RFPDupeFilter"
# 使用scrapy-redis组件自己的调度器
SCHEDULER = "scrapy_redis.scheduler.Scheduler"
# 是否允许暂停
SCHEDULER_PERSIST = True
8 配置Redis服务器地址和端口
# 如果redis服务器不在本机，则需如下配置
REDIS_HOST = ‘192.168.0.108‘
REDIS_PORT = 6379
REDIS_PARAMS = {"password":123456}
9 执行爬虫文件
scrapy runspider qiubai
10 向调度器队列中扔入一个起始url（在redis客户端中操作）：lpush redis_key属性值 起始url
lpush qiubaispider https://www.qiushibaike.com/pic/
实现代码
class QiubaiSpider(RedisCrawlSpider):
name = ‘qiubai‘
# allowed_domains = [‘www.qiushibaike.com/pic‘]
# start_urls = [‘http://www.qiushibaike.com/pic/‘]
redis_key = ‘qiubaispider‘ # 表示跟start_urls含义一样
link = LinkExtractor(allow=r‘/pic/page/\d+‘)
rules = (
Rule(link, callback=‘parse_item‘, follow=True),
)
def parse_item(self, response):
print(‘开始爬虫‘)
div_list = response.xpath(‘//*[@id="content-left"]/div‘)
for div in div_list:
print(div)
img_url = "http://" + div.xpath(‘.//div[@class="thumb"]/a/img/@src‘).extract_first()
item = RedisproItem()
item[‘img_url‘] = img_url
yield item
基于RedisSpider的分布式爬虫
案例需求：爬取的是基于文字的新闻数据(国内, 国际，军师， 航空)
- 1 在爬虫文件中导入webdriver类
- 2 在爬虫文件的爬虫类的构造方法中进行了浏览器实例化操作
- 3 在爬虫类的closed方法中进行浏览器的关闭操作
- 4 在下载中间件的process_response方法中编写执行浏览器自动化操作
wangyi.py：
middlewares.py:
from scrapy import signals
from scrapy.http import HtmlResponse
class WanyiproDownloaderMiddleware(object):
# 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.
def process_request(self, request, spider):
# Called for each request that goes through the downloader
# middleware.
# Must either:
# - return None: continue processing this request
# - or return a Response object
# - or return a Request object
# - or raise IgnoreRequest: process_exception() methods of
# installed downloader middleware will be called
return None
def process_response(self, request, response, spider):
# 拦截到响应对象(下载器传递给Spider的响应对象)
# request: 响应对象对应的请求对象
# response: 拦截到的响应对象
# spider: 爬虫文件对应的爬虫类的实例
print(request.url + "这是下载中间件")
# 响应对象中存储页面数据的篡改
if request.url in [‘http://news.163.com/domestic/‘, ‘http://news.163.com/world/‘, ‘http://war.163.com/‘,
‘http://news.163.com/air/‘]:
spider.bro.get(url=request.url)
js = ‘window.scrollTo(0,document.body.scrollHeight)‘
spider.bro.execute_script(js)
time.sleep(2) # 一定要给与浏览器一定的缓冲加载数据的时间
# 页面数据包含了动态加载出来的新闻数据对应的页面数据
page_text = spider.bro.page_source
return HtmlResponse(url=spider.bro.current_url, body=page_text, encoding=‘utf-8‘, request=request)
else:
return response
UA池和地址池：
from scrapy import signals
from scrapy.http import HtmlResponse
from scrapy.downloadermiddlewares.useragent import UserAgentMiddleware
import random
user_agent_list = [
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 "
"(KHTML, like Gecko) Chrome/22.0.1207.1 Safari/537.1",
"Mozilla/5.0 (X11; CrOS i686 2268.111.0) AppleWebKit/536.11 "
"(KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.6 "
"(KHTML, like Gecko) Chrome/20.0.1092.0 Safari/536.6",
"Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.6 "
"(KHTML, like Gecko) Chrome/20.0.1090.0 Safari/536.6",
"Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.1 "
"(KHTML, like Gecko) Chrome/19.77.34.5 Safari/537.1",
"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.5 "
"(KHTML, like Gecko) Chrome/19.0.1084.9 Safari/536.5",
"Mozilla/5.0 (Windows NT 6.0) AppleWebKit/536.5 "
"(KHTML, like Gecko) Chrome/19.0.1084.36 Safari/536.5",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
"Mozilla/5.0 (Windows NT 5.1) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_0) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
"Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3",
"Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
"Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
"Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
"(KHTML, like Gecko) Chrome/19.0.1061.0 Safari/536.3",
"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.24 "
"(KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24",
"Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/535.24 "
"(KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24"
]
# UA池代码的编写（单独给UA池封装一个下载中间件的一个类）
# 导包UserAgentMiddleware类
class RandomUserAgent(UserAgentMiddleware):
def process_request(self, request, spider):
# 从列表中随机抽选一个ua值
ua = random.choice(user_agent_list)
# ua值进行当前拦截到请求的ua的写入操作
request.headers.setdefault(‘User-Agent‘, ua)
# 可被选用的代理IP
PROXY_http = [
‘153.180.102.104:80‘,
‘195.208.131.189:56055‘,
]
PROXY_https = [
‘120.83.49.90:9000‘,
‘95.189.112.214:35508‘,
]
# 批量对拦截到的请求进行IP更换
class Proxy(object):
def process_request(self, request, spider):
# 对拦截到请求的url进行判断（协议头到底是http还是https）
# request.url返回值：http://www.xxx.com
h = request.url.split(‘:‘)[0] # 请求的协议头
if h == ‘https‘:
ip = random.choice(PROXY_https)
request.meta[‘proxy‘] = ‘https://‘ + ip
else:
ip = random.choice(PROXY_http)
request.meta[‘proxy‘] = ‘http://‘ + ip
基于RedisSpider实现分布式爬虫步骤
1 导包：from scrapy_redis.spiders import RedisSpider
2 将爬虫类的父类修改成RedisSpider
3 将起始URL列表注释, 添加一个redis_key(调度器队列的名称)的属性
4 进行redis数据库配置文件的配置：
- 将 bind 127.0.0.1 进行注释
- 将 protected-mode no 关闭保护模式
5 settings中配置redis
REDIS_HOST = ‘192.168.0.108‘
REDIS_PORT = 6379
REDIS_PARAMS = {"password": 123456}
# 使用scrapy-redis组件的去重队列
DUPEFILTER_CLASS = "scrapy_redis.dupefilter.RFPDupeFilter"
# 使用scrapy-redis组件自己的调度器
SCHEDULER = "scrapy_redis.scheduler.Scheduler"
# 是否允许暂停
SCHEDULER_PERSIST = True
ITEM_PIPELINES = {
‘scrapy_redis.pipelines.RedisPipeline‘: 400
}
6 执行爬虫文件
scrapy runspider wangyi.py
7 向调度器的管道中扔一个起始url
lpush wangyi https://news.163.com/
原文地址：https://www.cnblogs.com/harryblog/p/11376864.html
时间： 2024-08-30 05:20:30