[Python知识库]scrapy中parse()方法中常用的知识点1

成功代码如下：

import scrapy


class CnblogSpider(scrapy.Spider):
    name = 'cnblog'
    allowed_domains = ['cnblogs.com']
    start_urls = ['http://cnblogs.com/qiyeboy/default.html?page=1']

    def parse(self, response):
        # 实现网页的解析
        # 首先抽取所有的文章
        papers=response.xpath(".//*[@class='day']")
        # 从每篇文章中抽取数据
        for paper in papers:
            url = paper.xpath(".//*[@class='postTitle']/a/@href").extract_first()
            title = paper.xpath(".//*[@class='postTitle']/a/span/text()").extract()[0]
            time = paper.xpath(".//*[@class='dayTitle']/a/text()").extract()[0]
            content = paper.xpath(".//*[@class='postTitle']/a/span/text()").extract()[0]
            # print('%s,%s,%s,%s'%url%title%time%content)
            print(f'{url},{title},{time},{content}')

其中有两点是我写的时候调试出来的
1.

title = paper.xpath(".//*[@class='postTitle']/a/span/text()").extract()[0]

式子中正则这样写运行得到的结果是不准确的，得到的title如下

里面是带有标签

title = paper.xpath(".//*[@class='postTitle']/a/span/text()").extract()[0]

还有格式化打印多个字符串除了format()，还可以如上例中

f'{a},{b},{c}'

格式打印