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分布式爬虫scrapy-redis踩坑

Indra_ran 人气:0

一、安装redis

因为是在CentOS系统下安装的，并且是服务器。遇到的困难有点多不过。

1.首先要下载相关依赖

首先先检查是否有c语言的编译环境，你问我问什么下载这个，我只能说它是下载安装redis的前提，就像水和鱼一样。

rpm -q gcc```

如果输出版本号，则证明下载好了，否则就执行下面的命令，安装gcc，

2.然后编译redis

下载你想要的redis版本注意下面的3.0.6是版本号，根据自己想要的下载版本号，解压

yum install gcc-c++
cd /usr/local/redis
wget http://download.redis.io/releases/redis-3.0.6.tar.gz
tar zxvf redis-3.0.6.tar.gz
make && make install

什么？你问我没有redis文件夹怎么办，mkdir创建啊!!!

一定要先进入目录再去执行下载编译，这样下载的redis才会进入系统变量。

redis-server
redis-cli

启动服务你是下面这样的吗？

是的就不正常了！！你才下载好了，你会发现你可以开启服务了，但是退不出来，无法进入命令行了，变成下面的这鬼摸样了，别急，你还没配置好，慢慢来。

还记得你刚刚创建的redis文件夹吗？进入那里面，找到redis.conf，修改这个配置文件。

redis-server
redis-cli

找到这三个并改正。

保存退出，重启redis，这样，redis就配置好了，还可以设置密码，但是我懒，不想设置。

至此数据库配置成功

二、scrapy框架出现的问题

1.AttributeError: TaocheSpider object has no attribute make_requests_from_url 原因：

新版本的scrapy框架已经丢弃了这个函数的功能，但是并没有完全移除，虽然函数已经移除，但是还是在某些地方用到了这个，出现矛盾。

解决方法

自己在相对应的报错文件中重写一下这个方法
就是在

def make_requests_from_url(self,url):
	return scrapy.Request(url,dont_filter=True)

2.ValueError: unsupported format character : (0x3a) at index 9 问题：

我开起了redis的管道，将数据保存在了redis中，但是每次存储总是失败报错。

原因：

我在settings.py文件中重写了保存的方法，但是保存的写法不对导致我一直以为是源码的错误

# item存储键的设置
REDIS_ITEMS_KEY = '%(spider):items'

源码是

return self.spider % {"spider":spider.name}

太坑了，我为了这个错误差点重写了一个scrapy框架…

注意！如果你觉得你的主代码一点问题都没有，那就一定是配置文件的问题，大小写，配置环境字母不对等

三、scrapy正确的源代码

1.items.py文件

import scrapy
class MyspiderItem(scrapy.Item):
    # define the fields for your item here like:
    lazyimg = scrapy.Field()
    title = scrapy.Field()
    resisted_data = scrapy.Field()
    mileage = scrapy.Field()
    city = scrapy.Field()
    price = scrapy.Field()
    sail_price = scrapy.Field()

2.settings.py文件

# Scrapy settings for myspider 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 = 'myspider'

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

# Crawl responsibly by identifying yourself (and your website) on the user-agent

# Obey robots.txt rules
# 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://docs.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://docs.scrapy.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'myspider.middlewares.MyspiderSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'myspider.middlewares.MyspiderDownloaderMiddleware': 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
# Crawl responsibly by identifying yourself (and your website) on the user-agent
USER_AGENT = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36'

LOG_LEVEL = 'WARNING'
LOG_FILE = './log.log'
# Obey robots.txt rules
ROBOTSTXT_OBEY = False

# 指定管道 ，scrapy-redis组件帮我们写好
ITEM_PIPELINES = {
        "scrapy_redis.pipelines.RedisPipeline":400
}

# 指定redis
REDIS_HOST = '' # redis的服务器地址，我们现在用的是虚拟机上的回环地址
REDIS_PORT = # virtual Box转发redistribution的端口

# 去重容器类配置 作用：redis的set集合来存储请求的指纹数据，从而实现去重的持久化
DUPEFILTER_CLASS = 'scrapy_redis.dupefilter.RFPDupeFilter'

# 使用scrapy-redis的调度器
SCHEDULER = 'scrapy_redis.scheduler.Scheduler'

# 配置调度器是否需要持久化，爬虫结束的时候要不要清空redis中请求队列和指纹的set集合，要持久化设置为True
SCHEDULER_PERSIST = True

# 最大闲置时间，防止爬虫在分布式爬取的过程中关闭
# 这个仅在队列是SpiderQueue 或者 SpiderStack才会有作用，
# 也可以阻塞一段时间，当你的爬虫刚开始时（因为刚开始时，队列是空的）
SCHEDULER_IDLE_BEFORE_CLOSE = 10

# 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'

3.taoche.py文件

import scrapy
from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule
from scrapy_redis.spiders import RedisCrawlSpider
from ..items import MyspiderItem
import logging
log = logging.getLogger(__name__)
class TaocheSpider(RedisCrawlSpider):
    name = 'taoche'
    # allowed_domains = ['taoche.com'] # 不做域名限制
    # start_urls = ['http://taoche.com/'] # 起始的url应该去redis（公共调度器） 里面获取

    redis_key = 'taoche' # 回去redis（公共调度器）里面获取key为taoche的数据 taoche:[]
    # 老师，我给你找一下我改的源码在哪里，看看是那的错误吗
    rules = (
        # LinkExtractor 链接提取器，根据正则规则提取url地址
        # callback 提取出来的url地址发送请求获取响应，会把响应对象给callback指定的函数进行处理
        # follow  获取的响应页面是否再次经过rules进行提取url
        Rule(LinkExtractor(allow=r'/\?page=\d+?'),
             callback='parse_item',
             follow=True),
    )

    def parse_item(self, response):
        print("开始解析数据")
        car_list = response.xpath('//div[@id="container_base"]/ul/li')
        for car in car_list:

            lazyimg = car.xpath('./div[1]/div/a/img/@src').extract_first()
            title = car.xpath('./div[2]/a/span/text()').extract_first()
            resisted_data = car.xpath('./div[2]/p/i[1]/text()').extract_first()
            mileage = car.xpath('./div[2]/p/i[2]/text()').extract_first()
            city = car.xpath('./div[2]/p/i[3]/text()').extract_first()
            city = city.replace('\n', '')
            city = city.strip()
            price = car.xpath('./div[2]/div[1]/i[1]/text()').extract_first()
            sail_price = car.xpath('./div[2]/div[1]/i[2]/text()').extract_first()

            item = MyspiderItem()
            item['lazyimg'] = lazyimg
            item['title'] = title
            item['resisted_data'] = resisted_data
            item['mileage'] = mileage
            item['city'] = city
            item['price'] = price
            item['sail_price'] = sail_price
            log.warning(item)
            # scrapy.Request(url=function,dont_filter=True)
            yield item

4.其余文件

总结

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