Scrapy简介

Scrapy是一个为了爬取网站数据，提取结构性数据而编写的应用框架。

Scrapy入门请看官方文档：scrapy官方文档

本爬虫简介

本爬虫实现按分类爬取豆瓣电影信息，一次爬取一个分类，且自动切换代理池，防止ip在访问过多过频繁后无效。

分类如图所示：

实现-scrapy中间件

scrapy基础框架参考上面的官方教程，搭建好基础框架后，本爬虫特殊之处在于为了防止爬虫被封，采用了轮换代理和agent的中间件。

agent轮换池：

简单的写一个user_agent_list来使得每次的agent不同，原理简单，代码如下：

class RotateUserAgentMiddleware(UserAgentMiddleware):  #轮换代理agent
    def __init__(self, user_agent=''):
        self.user_agent = user_agent

    def process_request(self, request, spider):
        ua = random.choice(self.user_agent_list)
        if ua:
            #print '-----------------------Using user-agent:', ua, '------------------------'
            request.headers.setdefault('User-Agent', ua)

            # the default user_agent_list composes chrome,IE,firefox,Mozilla,opera,netscape

    # for more user agent strings,you can find it in http://www.useragentstring.com/pages/useragentstring.php
    user_agent_list = [ \
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/22.0.1207.1 Safari/537.1" \
        "Mozilla/5.0 (X11; CrOS i686 2268.111.0) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11", \
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.6 (KHTML, like Gecko) Chrome/20.0.1092.0 Safari/536.6", \
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.6 (KHTML, like Gecko) Chrome/20.0.1090.0 Safari/536.6", \
        "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/19.77.34.5 Safari/537.1", \
        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.9 Safari/536.5", \
        "Mozilla/5.0 (Windows NT 6.0) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.36 Safari/536.5", \
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3", \
        "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3", \
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_0) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3", \
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3", \
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3", \
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3", \
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3", \
        "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3", \
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 (KHTML, like Gecko) Chrome/19.0.1061.0 Safari/536.3", \
        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.24 (KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24", \
        "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/535.24 (KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24"
    ]

ip轮换池：

采用了一位大神cocoakekeyu写的中间件 Github地址，并不认识他，但是为他点赞。代码在这里不贴了，可以去Github看。

“一个用于scrapy爬虫的自动代理中间件。可自动抓取和切换代理，自定义抓取和切换规则。”

实现-爬虫实现

item.py

class DoubanItem(scrapy.Item):
    movie_name = scrapy.Field()
    movie_director = scrapy.Field()
    movie_writer = scrapy.Field()
    movie_starring = scrapy.Field()
    movie_category = scrapy.Field()
    movie_country = scrapy.Field()
    #movie_language = scrapy.Field()
    movie_date = scrapy.Field()
    movie_time = scrapy.Field()
    movie_star = scrapy.Field()
    movie_5score = scrapy.Field()
    movie_4score = scrapy.Field()
    movie_3score = scrapy.Field()
    movie_2score = scrapy.Field()
    movie_1score = scrapy.Field()
    movie_describe = scrapy.Field()
    pass

看这item名都不用我解释...

doubanlist_spider.py

先贴上代码：

class doubanlistSpider(scrapy.Spider):
    name = "doubanlist"
    allowed_domains = ["movie.douban.com"]
    start_urls = [
        "https://movie.douban.com/tag/%E5%8A%A8%E7%94%BB"
    ]


    def parse(self, response):
        for href in response.xpath('//a[@class="nbg"]/@href'):
            url = href.extract()
            yield scrapy.Request(url, callback=self.parse_each_movie)
        next_page = response.xpath('//span[@class="next"]/a/@href').extract()
        if next_page:
            print '--------------Finding next page: [%s] --------------------------', next_page
            yield scrapy.Request(next_page[0], callback=self.parse)
        else:
            print '--------------There is no more page!--------------------------'


    def parse_each_movie(self, response):
        item = DoubanItem()
        item['movie_name'] = response.xpath('//span[@property="v:itemreviewed"]/text()').extract()
        item['movie_director'] = response.xpath('//a[@rel="v:directedBy"]/text()').extract()
        item['movie_writer'] = response.xpath('//span[@class="attrs"][2]/a/text()').extract()
        item['movie_starring'] = response.xpath('//a[@rel="v:starring"]/text()').extract()
        item['movie_category'] = response.xpath('//span[@property="v:genre"]/text()').extract()
        #item['movie_language'] = response.xpath('//*[@id="info"]').re(r'</span> (.*)<br>\n')[2]
        item['movie_date'] = response.xpath('//span[@property="v:initialReleaseDate"]/text()').extract()
        item['movie_time'] = response.xpath('//span[@property="v:runtime"]/text()').extract()
        item['movie_star'] = response.xpath('//strong[@property="v:average"]/text()').extract()
        item['movie_5score'] = response.xpath('//span[@class="rating_per"][1]/text()').extract()
        item['movie_4score'] = response.xpath('//span[@class="rating_per"][2]/text()').extract()
        item['movie_3score'] = response.xpath('//span[@class="rating_per"][3]/text()').extract()
        item['movie_2score'] = response.xpath('//span[@class="rating_per"][4]/text()').extract()
        item['movie_1score'] = response.xpath('//span[@class="rating_per"][5]/text()').extract()
        item['movie_describe'] = response.xpath('//*[@id="link-report"]/span/text()').re(r'\S+')

        check_item = response.xpath('//*[@id="info"]').re(r'</span> (.*)<br>\n')[1]
        result = self.check_contain_chinese(check_item)
        if result:
            item['movie_country'] = response.xpath('//*[@id="info"]').re(r'</span> (.*)<br>\n')[1]
        else:
            item['movie_country'] = response.xpath('//*[@id="info"]').re(r'</span> (.*)<br>\n')[2]

        yield item

    def check_contain_chinese(self, check_str):
        for ch in check_str.decode('utf-8'):
            if u'\u4e00' <= ch <= u'\u9fff':
                return True
        return False

def parse(self, response)：从https://movie.douban.com/tag/%E5%8A%A8%E7%94%BB（某一特定分类）开始，爬取20条本页的电影，之后判定“下一页”按钮是否存在，如果存在则继续爬取下一页。

def parse_each_movie(self, response):对于每个电影详细页，爬取所需要的信息，全部使用xpath

中间一段是在爬取电影国家信息时，由于有不同情况的网页（可能是新老页面交替），需要不同处理，不然会爬到不正确的信息，xpath定位不准。

def check_contain_chinese：为了确定爬取的中文内容为中文字符串，需要进行判断。

总结

具体项目请查看：https://github.com/qqxx6661/scrapy_yzd

我爱周雨楠

【scrapy】scrapy按分类爬取豆瓣电影基础信息