scrapy：CrawlSpider及其案例

1. CrawSpider介绍

运行原理：

2. pymysql

conda install pymysql

3. 案例-读书网爬虫&数据入库

3.1 案例需求

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3.2 网页分析

3.3 创建爬虫项目

3.4 创建爬虫文件（与之前有区别）

scrapy genspider -t crawl read https://www.dushu.com/book/1188.html

3.5 实现爬虫

import scrapy
from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule

from scrapy_readbook_6.items import ScrapyReadbook6Item


class ReadSpider(CrawlSpider):
    name = "read"
    allowed_domains = ["www.dushu.com"]
    start_urls = ["https://www.dushu.com/book/1188_1.html"]  # 注意要_1，不然就不符合Rule，导致取不到第一页

    rules = (Rule(
        LinkExtractor(allow=r"/book/1188_\d+\.html"),  # 正则；需要修改allowed_domains为域名范围
        callback="parse_item",
        follow=False
    ),)

    def parse_item(self, response):
        # 爬取图片和书名
        img_list = response.xpath('//div[@class="bookslist"]//img')
        for img in img_list:
            name = img.xpath('./@data-original').extract_first()
            src = img.xpath('./@alt').extract_first()
            book = ScrapyReadbook6Item(name=name, src=src)
            yield book

scrapy crawl read

3.6 实现入库

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: https://docs.scrapy.org/en/latest/topics/item-pipeline.html


# useful for handling different item types with a single interface
from itemadapter import ItemAdapter


class ScrapyReadbook6Pipeline:
    def open_spider(self, spider):
        self.fp = open('book.json', 'w', encoding='utf-8')

    def process_item(self, item, spider):
        self.fp.write(str(item))
        return item

    def close_spider(self, spider):
        self.fp.close()


from scrapy.utils.project import get_project_settings  # 加载settings文件
import pymysql
class MysqlPipeline:
    def open_spider(self, spider):
        settings = get_project_settings()
        self.host = settings['DB_HOST']
        self.port =settings['DB_PORT']
        self.user =settings['DB_USER']
        self.password =settings['DB_PASSWROD']
        self.name =settings['DB_NAME']
        self.charset =settings['DB_CHARSET']
        self.connect()

    def connect(self):
        self.conn = pymysql.connect(
                            host=self.host,
                            port=self.port,
                            user=self.user,
                            password=self.password,
                            db=self.name,
                            charset=self.charset
        )
        self.cursor = self.conn.cursor()

    def process_item(self, item, spider):
        sql = 'insert into book(name,src) values("{}","{}")'.format(item['name'], item['src'])
        # 执行sql语句
        self.cursor.execute(sql)
        # 提交
        self.conn.commit()
        return item

    def close_spider(self, spider):
        self.cursor.close()
        self.conn.close()

scrapy crawl read