爬虫关于xpath在代码中返回为空的问题_美剧天堂电影爬取的案例

Question

D:\hailong\scrapy\movie>Scrapy crawl meiju
2021-05-13 22:29:09 [scrapy.utils.log] INFO: Scrapy 2.5.0 started (bot: movie)
2021-05-13 22:29:09 [scrapy.utils.log] INFO: Versions: lxml 4.6.3.0, libxml2 2.9.5, cssselect 1.1.0, parsel 1.6.0, w3lib 1.22.0, Twisted 21.2.0, Python 3.6.3 (v3.6.3:2c5fed8, Oct  3 2017, 18:11:49) [MSC v.1900 64 bit (AMD64)], pyOpenSSL 20.0.1 (OpenSSL 1.1.1k  25 Mar 2021), cryptography 3.4.7, Platform Windows-10-10.0.18362-SP0
2021-05-13 22:29:09 [scrapy.utils.log] DEBUG: Using reactor: twisted.internet.selectreactor.SelectReactor
2021-05-13 22:29:09 [scrapy.crawler] INFO: Overridden settings:
{'BOT_NAME': 'movie',
 'DOWNLOAD_DELAY': 1,
 'NEWSPIDER_MODULE': 'movie.spiders',
 'SPIDER_MODULES': ['movie.spiders']}
2021-05-13 22:29:09 [scrapy.extensions.telnet] INFO: Telnet Password: d70954f5035d6949
2021-05-13 22:29:09 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.logstats.LogStats']
2021-05-13 22:29:09 [scrapy.middleware] INFO: Enabled downloader middlewares:
['scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
 'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
 'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
 'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
 'scrapy.downloadermiddlewares.retry.RetryMiddleware',
 'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
 'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
 'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
 'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2021-05-13 22:29:09 [scrapy.middleware] INFO: Enabled spider middlewares:
['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
 'scrapy.spidermiddlewares.referer.RefererMiddleware',
 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
 'scrapy.spidermiddlewares.depth.DepthMiddleware']
2021-05-13 22:29:09 [scrapy.middleware] INFO: Enabled item pipelines:
['movie.pipelines.MoviePipeline']
2021-05-13 22:29:09 [scrapy.core.engine] INFO: Spider opened
2021-05-13 22:29:09 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2021-05-13 22:29:09 [scrapy.extensions.telnet] INFO: Telnet console listening on 127.0.0.1:6023
2021-05-13 22:29:09 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://www.meijutt.tv/new100.html> (referer: None)
888888888
[]
2021-05-13 22:29:10 [scrapy.core.engine] INFO: Closing spider (finished)
2021-05-13 22:29:10 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 225,
 'downloader/request_count': 1,
 'downloader/request_method_count/GET': 1,
 'downloader/response_bytes': 7510,
 'downloader/response_count': 1,
 'downloader/response_status_count/200': 1,
 'elapsed_time_seconds': 0.237611,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2021, 5, 13, 14, 29, 10, 87193),
 'httpcompression/response_bytes': 48328,
 'httpcompression/response_count': 1,
 'log_count/DEBUG': 1,
 'log_count/INFO': 10,
 'response_received_count': 1,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'start_time': datetime.datetime(2021, 5, 13, 14, 29, 9, 849582)}
2021-05-13 22:29:10 [scrapy.core.engine] INFO: Spider closed (finished)

以下是代码部分：

meiju.py

import scrapy
from movie.items import MovieItem

class MeijuSpider(scrapy.Spider):#继承这个类
    name = 'meiju'#名字
    allowed_domains = ['meijutt.tv']#域名
    start_urls = ['https://www.meijutt.tv/new100.html']#要补充完整

    def parse(self, response):
        print(888888888)
        movies = response.xpath('//ul[@class="top-list fn-clear"]/li')#意思是选中所有的属性class值为"top-list fn-clear"的ul下的li标签内容
        print(movies)
        for each_movie in movies:
            item = MovieItem()
            item['name'] = each_movie.xpath('./h5/a/@title').extract()[0]
            # .表示选取当前节点，也就是对每一项li，其下的h5下的a标签中title的属性值
            yield item #一种特殊的循环

settings.py

ITEM_PIPELINES = {'movie.pipelines.MoviePipeline':100}
ROBOTSTXT_OBEY = False
DOWNLOAD_DELAY = 1

items.py

import scrapy

class MovieItem(scrapy.Item):
    name = scrapy.Field()

pipelines.py

import json
from itemadapter import ItemAdapter

class MoviePipeline(object):
    def process_item(self, item, spider):
        return item

Answer 1

少了一个空格，没有选中li元素