如何使用scrapy爬取猫眼电影最受期待榜前20并保存到csv文件中

首先需要安装scrapy，可以使用以下命令进行安装：

pip install scrapy

然后创建一个新的scrapy项目和一个爬虫：

scrapy startproject maoyan
cd maoyan
scrapy genspider maoyan_spider maoyan.com

接下来，打开 `maoyan_spider.py` 文件，在 `start_urls` 列表中添加猫眼电影最受期待榜的链接：

start_urls = ['https://maoyan.com/films?showType=3']

然后在 `parse` 方法中编写爬取逻辑：

def parse(self, response):
    movies = response.xpath('//div[@class="movie-item film-channel"]')[:20]
    for movie in movies:
        title = movie.xpath('./a/@title').extract_first().strip()
        release_time = movie.xpath('./div[2]/text()').extract_first().strip()
        yield {'title': title, 'release_time': release_time}

上面的代码使用 `xpath` 提取了每个电影的标题和上映时间，并使用 `yield` 将结果返回。注意，我们只提取前20个电影。

最后，可以使用以下命令运行爬虫并将结果保存到 `movies.csv` 文件中：

scrapy crawl maoyan_spider -o movies.csv

完整的爬虫代码如下：

import scrapy


class MaoyanSpiderSpider(scrapy.Spider):
    name = 'maoyan_spider'
    allowed_domains = ['maoyan.com']
    start_urls = ['https://maoyan.com/films?showType=3']

    def parse(self, response):
        movies = response.xpath('//div[@class="movie-item film-channel"]')[:20]
        for movie in movies:
            title = movie.xpath('./a/@title').extract_first().strip()
            release_time = movie.xpath('./div[2]/text()').extract_first().strip()
            yield {'title': title, 'release_time': release_time}

希望能够帮助到你。