爬虫Scrapy框架学习（五）-东莞阳光热线问政平台爬取案例

本案例通过典型的scrapy框架Spider类展现了一个模板式的爬虫过程，请读者细细体会，此案例为必会项目,按照本博客配置，完美通过.本文还对item做了限制，编写item文件的主要作用是防止爬取数据存入子字典中的键值命名错误.

1.项目框架展示

2.爬取页面展示

3.yg.py文件

# -*- coding: utf-8 -*-
import scrapy
from yangguang.items import YangguangItem

class YgSpider(scrapy.Spider):
    name = 'yg'
    allowed_domains = ['sun0769.com']
    start_urls = ['http://wz.sun0769.com/index.php/question/report?page=']

    def parse(self, response):
        #分组
        tr_list = response.xpath("//div[@class='greyframe']/table[2]/tr/td/table/tr")
        for tr in tr_list:
            item = YangguangItem() #实例化爬取的数据限制（防止命名错误）
            item["title"] = tr.xpath("./td[2]/a[@class='news14']/@title").extract_first()
            item["href"] = tr.xpath("./td[2]/a[@class='news14']/@href").extract_first()
            item["publish_date"] = tr.xpath("./td[last()]/text()").extract_first()

            #进去详情页
            yield scrapy.Request(
                item["href"],
                callback = self.parse_detail,
                meta = {"item":item},
            )

        #翻页
        next_url = response.xpath("//a[text() = '>']/@href").extract_first()
        if next_url is not None:#判断是否有下一页
            yield scrapy.Request(
                next_url,
                callback = self.parse
            )


    def parse_detail(self, response):
        """处理详情页"""
        item = response.meta["item"]
        item["content"] = response.xpath("//td[@class = 'txt16_3']//text()").extract_first() #选取多个选项
        item["content_img"] = response.xpath("//div[@class = 'c1 text14_2']//img/@src").extract()
        item["content_img"] = ["http://wz.sun0769.com/" + i for i in item["content_img"]] #列表推导式添加图片前面缺失的域名
        # print(item)
        yield item #输出到pipeline

4.item.py文件

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

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

import scrapy


class YangguangItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    title = scrapy.Field()
    href = scrapy.Field()
    publish_date = scrapy.Field()
    content_img = scrapy.Field()
    content = scrapy.Field()

5.pipeline.py文件

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

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://doc.scrapy.org/en/latest/topics/item-pipeline.html
import re

class YangguangPipeline(object):
    def open_spider(self, response): #在爬虫开始时打开一次和关闭时打开一次，而且只执行一次
        pass
    def close_spider(self, response):#但是如果在结束中统一保存文件，如果在程序中间出错了就不会保存已经爬取的数据了。
        pass


    def process_item(self, item, spider):
        item["content"] = self.process_content(item["content"])
        print(item)
        return item

    def process_content(self, content):#处理content内容，去除无关信息

        # contnet = [re.sub(r"\xa0|\s","",i) for i in content] #content为列表的情况
        # contnet = re.sub(r"\xa0","",content)
        # content = [i for i in content if len(i) > 0]#去除列表中的空字符串
        # print(content)

        content = re.sub("\xa0", "", content)#content为字符串
        return content

6.settings.py文件

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

# Scrapy settings for yangguang 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 = 'yangguang'

SPIDER_MODULES = ['yangguang.spiders']                            #爬虫位置
NEWSPIDER_MODULE = 'yangguang.spiders'                            #新建爬虫的放置位置

LOG_LEVEL = "WARNING"


# 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 = True                                             #默认情况下是否遵守robot协议

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32                                         #设置最大并发请求（默认是16个）

# 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                                               #下载延迟（使整个爬虫慢一些，防止反爬虫）
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16                              #每一个域名的最大并发请求数（几乎不会用到）
#CONCURRENT_REQUESTS_PER_IP = 16                                  #每一个id的最大并发请求数（几乎不会用到）

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False                                           #cookie是否开启（默认是开启的）

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

# Override the default request headers:                            #默认请求头
#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 = {                                             #爬虫中间件
#    'yangguang.middlewares.YangguangSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://doc.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {                                          #下载中间件
#    'yangguang.middlewares.YangguangDownloaderMiddleware': 543,
#}

# 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 = {
   'yangguang.pipelines.YangguangPipeline': 300,
}

# Enable and configure the AutoThrottle extension (disabled by default)  #自动限速（一般不需要）
# 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)                    #http缓存
# 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'

7.结果展示

• content_img为空是因为在详情页并没有配图，有配图便可以爬取到,请读者自行查看网页源代码进行核验。