Scrapy抓取Quotes to Scrape

# 爬虫主程序quotes.py
# -*- coding: utf-8 -*-
import scrapy
from quotetutorial.items import QuoteItem
# 启动爬虫
# 请求都是默认的，我们不需要管请求的操作，只要关心解析的过程就可以了
class QuotesSpider(scrapy.Spider):
    name = "quotes"
    allowed_domains = ["quotes.toscrape.com"]
    start_urls = ['http://quotes.toscrape.com/']
# python默认执行了相当一部分操作,比如这里,有了start_urls以后,会默认启用start_requests方法,该方法遍历得到每一个url,并且调用make_requests_from_url进行请求,返回response给parse函数
    # 请求得到的结果，回调给parse，response即相应结果
    def parse(self, response):
        quotes = response.css('.quote')
        for quote in quotes:
            # 如果只有一个内容，可以用extract_first，如果有多个内容可以用extract全部提取出来
            # 可以用scrapy-conda shell  quotes.toscrape.com 进入到命令行交互模式下
            item = QuoteItem()
            text = quote.css('.text::text').extract_first()
            author = quote.css('.author::text').extract_first()
            tags = quote.css('.tags .tag::text').extract()
            item['text'] = text
            item['author'] = author
            item['tags'] = tags
            yield item
        # 获取下一页的相对url
        next = response.css('.pager .next a::attr(href)').extract_first()
        # 拼接成绝对url
        url = response.urljoin(next)
        #递归调用，循环打开下一页
        yield scrapy.Request(url = url, callback=self.parse)
        # 可以用scrapy-conda crawl quotes -o 文件名+扩展名
        # quotes.json/quotes.jl/quotes.csv/quotes.pickle/quotes.xml/quotes.marshal导出各种格式
        # ftp://user:pass@ftp.exampel.com/path/quotes.csv 可以远程ftp保存

# items定义的项目数据结构
# -*- coding: utf-8 -*-
# Define here the models for your scraped items
#
# See documentation in:
# http://doc.scrapy.org/en/latest/topics/items.html
# items相当于定义一个数据结构，给它指定一个个字段，比如标题，图片，文本内容等
import scrapy

class QuoteItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    text = scrapy.Field()
    author = scrapy.Field()
    tags = scrapy.Field()

# 中间储藏环节middlewares.py
# -*- coding: utf-8 -*-

# Define here the models for your spider middleware
#
# See documentation in:
# http://doc.scrapy.org/en/latest/topics/spider-middleware.html

from scrapy import signals

class QuotetutorialSpiderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the spider middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_spider_input(response, spider):
        # Called for each response that goes through the spider
        # middleware and into the spider.

        # Should return None or raise an exception.
        return None

    def process_spider_output(response, result, spider):
        # Called with the results returned from the Spider, after
        # it has processed the response.

        # Must return an iterable of Request, dict or Item objects.
        for i in result:
            yield i

    def process_spider_exception(response, exception, spider):
        # Called when a spider or process_spider_input() method
        # (from other spider middleware) raises an exception.

        # Should return either None or an iterable of Response, dict
        # or Item objects.
        pass

    def process_start_requests(start_requests, spider):
        # Called with the start requests of the spider, and works
        # similarly to the process_spider_output() method, except
        # that it doesn’t have a response associated.

        # Must return only requests (not items).
        for r in start_requests:
            yield r

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)

# pipelines.py管道环节,可决定数据如何处理
# -*- coding: utf-8 -*-

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: http://doc.scrapy.org/en/latest/topics/item-pipeline.html
from scrapy.exceptions import DropItem
import pymongo
#判断文本长度是否超过某一界限
class TextPipeline(object):
    def __init__(self):
        self.limit = 50

    def process_item(self, item, spider):
        if item['text']:
            if len(item['text']) > self.limit:
                item['text'] = item['text'][0:self.limit].rstrip() + '...'
            return item
        else:
            return DropItem('Missing Text')

class MongoPipeline(object):
    def __init__(self, mongo_url,mongo_db):
        self.mongo_url = mongo_url
        self.mongo_db = mongo_db

    @classmethod
    def from_crawler(cls,crawler):
        return cls(
            mongo_url = crawler.settings.get('MONGO_URL'),
            mongo_db = crawler.settings.get('MONGO_DB')
        )
    # mongodb的初始化对象
    def open_spider(self,spider):
        self.client = pymongo.MongoClient(self.mongo_url)
        self.db = self.client[self.mongo_db]

    # 保存到mongodb
    def process_item(self, item, spider):
        name = item.__class__.__name__
        self.db[name].insert(dict(item))
        return item #千万要注意,这里不要忘了返回,否则就会显示None
    def close_spider(self,spider):
        self.client.close()

# 配置文件
# -*- coding: utf-8 -*-

# Scrapy settings for quotetutorial project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     http://doc.scrapy.org/en/latest/topics/settings.html
#     http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#     http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'quotetutorial'

SPIDER_MODULES = ['quotetutorial.spiders']
NEWSPIDER_MODULE = 'quotetutorial.spiders'
MONGO_URL = 'localhost'
MONGO_DB = 'quotetutorial'

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

# Obey robots.txt rules
ROBOTSTXT_OBEY = True

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See http://scrapy.readthedocs.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 http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'quotetutorial.middlewares.QuotetutorialSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'quotetutorial.middlewares.MyCustomDownloaderMiddleware': 543,
#}

# Enable or disable extensions
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}

# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
   # 'quotetutorial.pipelines.TextPipeline': 300,
   'quotetutorial.pipelines.MongoPipeline': 400,
}

# Enable and configure the AutoThrottle extension (disabled by default)
# See http://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)
# See http://scrapy.readthedocs.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'

# 利用scrapy爬取quotes.toscrape.com网站
# 第一步,分析目标网站,确定数据结构,即要爬取的项目构成.去items里面设置对应项目
# 第二步,爬取首页信息,分析首页,提取项目items
# 第三步,首页抓取下一页信息,循环递归调用request请求,实现翻页爬取
# 第四步,修改settings,pipelines等,实现对items的修改,清洗,梳理以及存储