Based on the framework of a distributed crawler scrapy

distributed

• The concept: You can use more than one computer components of a distributed fleet, allowed to perform the same set of programs, the same set of network resources for joint crawling.

• scrapy native can not be achieved distributed

  • The scheduler can not be shared
  • Pipeline can not be shared

• scrapy + redis (scrapy & scrapy-redis components) based implementation of distributed

• scrapy-redisComponent Role:

  • It can be provided and shared pipeline scheduler

• Installation Environment:

  pip install scrapy-redis

• Encoding process:

  1.创建工程
  
  2.cd proName
  
  3.创建crawlspider的爬虫文件
  
  4.修改一下爬虫类：
      - 导包：from scrapy_redis.spiders import RedisCrawlSpider
      - 修改当前爬虫类的父类：RedisCrawlSpider
      - allowed_domains和start_urls删除
      - 添加一个新属性：redis_key = 'xxxx'可以被共享的调度器队列的名称
  
  5.修改配置settings.py
      - 指定管道
          ITEM_PIPELINES = {
                  'scrapy_redis.pipelines.RedisPipeline': 400
              }
      - 指定调度器
  增加了一个去重容器类的配置, 作用使用Redis的set集合来存储请求的指纹数据, 从而实现请求去重的持久化
          DUPEFILTER_CLASS = "scrapy_redis.dupefilter.RFPDupeFilter"
          # 使用scrapy-redis组件自己的调度器
          SCHEDULER = "scrapy_redis.scheduler.Scheduler"
          # 配置调度器是否要持久化, 也就是当爬虫结束了, 要不要清空Redis中请求队列和去重指纹的set。如果是True, 就表示要持久化存储, 就不清空数据, 否则清空数据
          SCHEDULER_PERSIST = True
      - 指定redis数据库
          REDIS_HOST = '127.0.0.1'
          REDIS_PORT = 6379
  
   6.配置redis数据库（redis.windows.conf）
      - 关闭默认绑定
          - 56Line：#bind 127.0.0.1
      - 关闭保护模式
          - 75line：protected-mode no
  
   7.启动redis服务（携带配置文件）和客户端
      - redis-server.exe redis.windows.conf
      - redis-cli
  
   8.执行工程
      - scrapy runspider spider.py
  
   9.将起始的url仍入到可以被共享的调度器的队列（sun）中
      - 在redis-cli中操作：lpush sun www.xxx.com
  
   10.redis:
      - xxx:items:存储的就是爬取到的数据

  Reptile Code:

  # -*- coding: utf-8 -*-
  import scrapy
  from scrapy.linkextractors import LinkExtractor
  from scrapy.spiders import CrawlSpider, Rule
  from scrapy_redis.spiders import RedisCrawlSpider
  from fbsPro.items import FbsproItem
  class FbsSpider(RedisCrawlSpider):
      name = 'fbs'
      # allowed_domains = ['www.xxx.com']
      # start_urls = ['http://www.xxx.com/']
  
      redis_key = 'sun'     # 可以被共享的调度器队列的名称
  
      link = LinkExtractor(allow=r'type=4&page=\d+')
      rules = (
          Rule(link, callback='parse_item', follow=True),
      )
  
      def parse_item(self, response):
          tr_list = response.xpath('//*[@id="morelist"]/div/table[2]//tr/td/table//tr')
          for tr in tr_list:
              title = tr.xpath('./td[2]/a[2]/@title').extract_first()
              status = tr.xpath('./td[3]/span/text()').extract_first()
  
              item = FbsproItem()
              item['title'] = title
              item['status'] = status
  
              yield item