网络爬虫——爬取网站所有Python书籍到数据库（Scrapy从入门到精通第二天）

如果大家没有看第一天的课程，必须去看一下，不然看不懂今天的课程的！

点我查看第一天内容：Scrapy框架的安装与创建 Scrapy从入门到精通第一天

一、课程介绍

今天我做的项目是利用Scrapy框架爬取当当网站Python相关书籍到数据库

今天的目标是：
一、获取当当网所有有关python书籍的名字
二、获取当当网所有有关python书籍的链接
三、获取当当网所有有关python书籍的评论数量
四、将获取到的数据存入到数据库中
五、最终结果

1、获取当当网域名

这个就比较容易啦，百度搜索就出来了
域名是“dangdang.com”注意域名是不带http://www.的

2、获取爬取内容的首页

我们只要是在上面粘贴就好啦，我们的起始网址是：
http://search.dangdang.com/?key=python&act=input

所有我们的爬虫文件应该这样写
这里我们用的匹配方式是XPath表达式，大家使用正则表达式也可以，

3、编写爬虫文件，这里我将爬虫命名为fst.py

上一章节有介绍生成爬虫项目和爬虫文件的介绍

# -*- coding: utf-8 -*-
import scrapy
from demo.items import DemoItem
from scrapy.http import Request

#scrapy crawl fst运行

class FstSpider(scrapy.Spider):
    name = 'fst' #爬虫名称
    allowed_domains = ['dangdang.com'] #可爬取的域名
    start_urls = ['http://search.dangdang.com/?key=python&act=input'] #起始网址

    def parse(self, response): #回调函数response相应信息
        item = DemoItem()
        item["title"] = response.xpath("//a[@name='itemlist-title']/@title").extract()
        item["link"] = response.xpath("//a[@name='itemlist-title']/@href").extract()
        item["comment"] = response.xpath("//a[@name='itemlist-review']/text()").extract()

        yield item #跳转到pipelines.py文件在这个文件中将数据保存到数据库

        for i in range(2,101):#获取100页的内容
            url = "http://search.dangdang.com/?key=python&act=input&page_index=" + str(i) #实现翻页功能
            yield Request(url,callback=self.parse)

4、编写：pipelines.py文件

将数据保存到数据库需要安装pymysql，python的一个模块。
控制台输入pip install pymysql 即可安装成功
安装成功还要解决编码的问题，因为源文件"charset="默认是空的，咱们找到他并加上utf8
文件修改方法位置：
修改python环境目录下lib/site-packages/pymysql/connections.py#不知道的环境在哪的小伙伴就去搜索pymysql就行，就是慢点
#进入connectioins.py搜索"charset="默认是空的，咱们加上utf8

# -*- coding: utf-8 -*-

import pymysql

class DemoPipeline(object):
    def process_item(self, item, spider):
		#创建数据库链接
        conn = pymysql.connect(host="127.0.0.1",user="root",passwd="123",db="test")
        for i in range(0,len(item["title"])):
        	#将爬取的信息数组分离，存储在单个文件中
            title = item["title"][i]
            link = item["link"][i]
            comment = item["comment"][i]
            #数据库插入语句
            sql="insert into books(title,link,comment) values('" + title + " ',' " + link + " ',' " + comment + "')"
            conn.query(sql)
            conn.commit()
        conn.close()
        return item

5、最后一步更改配置文件settings.py

这里不用自己写代码，这就是框架的好处，
我们只需要将67，68，69三行代码的注释解开即可
当当网不需要服务器伪装，所以这里我就没写服务器伪装
服务器伪装的话主要修改下代码里面的USER_AGENT即可

# -*- coding: utf-8 -*-

# Scrapy settings for demo project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     https://docs.scrapy.org/en/latest/topics/settings.html
#     https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#     https://docs.scrapy.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'demo'

SPIDER_MODULES = ['demo.spiders']
NEWSPIDER_MODULE = 'demo.spiders'


# Crawl responsibly by identifying yourself (and your website) on the user-agent
# USER_AGENT = 'demo (+http://www.yourdomain.com)'

# Obey robots.txt rules
ROBOTSTXT_OBEY = True

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See https://docs.scrapy.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

# Override the default request headers:
#DEFAULT_REQUEST_HEADERS = {
#   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
#   'Accept-Language': 'en',
#}

# Enable or disable spider middlewares
# See https://docs.scrapy.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'demo.middlewares.DemoSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'demo.middlewares.DemoDownloaderMiddleware': 543,
#}

# Enable or disable extensions
# See https://docs.scrapy.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}

# Configure item pipelines
# See https://docs.scrapy.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
   'demo.pipelines.DemoPipeline': 300,
}

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = 'httpcache'
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

二、获取源代码

代码代写(实验报告、论文、小程序制作)服务请加微信：ppz2759
关注下方公众号，回复“爬虫130”即可获取源代码