網絡爬蟲--22.【CrawlSpider實戰】實現微信小程序社區爬蟲

一. CrawlSpider

現實情況下，我們需要對滿足某個特定條件的url進行爬取，這時候就可以通過CrawlSpider完成。

CrawlSpider繼承自Spider，只不過在之前的基礎上增加了新的功能，可以定義爬取的url規則，Scrapy碰到滿足條件的url都進行爬取，而不用手動的yield Request。

二. CrawlSpider案例

1. 目錄結構

2. wxapp_spider.py

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


class WxappSpiderSpider(CrawlSpider):
    name = 'wxapp_spider'
    allowed_domains = ['wxapp-union.com']
    start_urls = ['http://www.wxapp-union.com/portal.php?mod=list&catid=1&page=1']

    rules = (
        Rule(LinkExtractor(allow=r'.+mod=list&catid=1&page=\d'),  follow=True),
        Rule(LinkExtractor(allow=r'.+article-.+\.html'), callback='parse_detail', follow=False)
    )

    def parse_detail(self, response):
        title = response.xpath("//h1[@class='ph']/text()").get()
        # print(title)
        author_p = response.xpath(".//p[@class='authors']")
        author = author_p.xpath("./a/text()").get()
        pub_time = author_p.xpath("./span/text()").get()
        # print('author:%s/pub_time:%s'%(author,pub_time))
        article_content = response.xpath(".//td[@id='article_content']//text()").getall()
        content = "".join(article_content).strip()
        # print(content)
        # print('-'*30)
        item = WxappItem(title=title,author=author,pub_time=pub_time,content=content)
        yield item

3. items.py

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

# Define here the models for your scraped items
#
# See documentation in:
# https://docs.scrapy.org/en/latest/topics/items.html

import scrapy


class WxappItem(scrapy.Item):
    # define the fields for your item here like:
    title = scrapy.Field()
    author = scrapy.Field()
    pub_time = scrapy.Field()
    content = scrapy.Field()

4. pipelines.py

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

# 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
from scrapy.exporters import JsonLinesItemExporter


class WxappPipeline(object):
    def __init__(self):
        self.fp = open('wxjc.json','wb')
        self.exporter = JsonLinesItemExporter(self.fp,ensure_ascii=False,encoding='utf-8')

    def process_item(self, item, spider):
        self.exporter.export_item(item)
        return item

    def close_spider(self,spider):
        self.fp.close()

5. settings.py

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

# Scrapy settings for wxapp 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 = 'wxapp'

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


# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'wxapp (+http://www.yourdomain.com)'

# 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 = 1
# 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 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.75 Safari/537.36'
}

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

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'wxapp.middlewares.WxappDownloaderMiddleware': 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 = {
   'wxapp.pipelines.WxappPipeline': 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'

6. start.py

from scrapy import cmdline

cmdline.execute("scrapy crawl wxapp_spider".split())

三. 重點總結