Scrapy的简单用法

首先执行如下命令创建一个scrapy项目

scrapy startproject kaijiang

主要有如下几个核心文件：

items.py: 在项目的根目录

middlewares.py: 在项目的根目录

pipelines.py: 在项目的根目录

kaijiang.py: 在spiders目录

settings.py: 在项目的根目录

我的实例是爬取和讯人物信息，一个实例地址为：http://kaijiang.500.com

项目目标是：根据几个初始的url，爬取到html源码，并从源码中提取出同样的url，进行迭代爬取

我们还要创建一个数据库,因为要把提取到的内容存储到数据库中

创建库的命令:
create database shuangseqiu charset=utf8;
选中库命令:
use shuangseqiu;
创建表的命令:
create table kaijiang(times varchar(100),hong varchar(100),lan varchar(100));

然后就看下面的操作就可以了

第一，item.py文件的内容如下：

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

# Define here the models for your scraped items
#
# See documentation in:
# https://doc.scrapy.org/en/latest/topics/items.html

import scrapy


class ShuangseqiuItem(scrapy.Item):
    # define the fields for your item here like:
    url = scrapy.Field()
    times = scrapy.Field()
    hong = scrapy.Field()
    lan = scrapy.Field()

该文件的作用是：定义需要从html中抽取出来的字段名称

第二，spiders目录下的kaijiang.py文件内容，我的名字是叫kaijiang.py

# -*- coding: utf-8 -*-
import scrapy
from ShuangSeqiu.items import ShuangseqiuItem

class KaijiangSpider(scrapy.Spider):
    name = 'kaijiang'
    allowed_domains = ['kaijiang.500.com']
    start_urls = ['http://kaijiang.500.com/shtml/ssq/19002.shtml']

    def parse(self, response):
        # item = ShuangseqiuItem()
        se_url = response.xpath('//div[@class="iSelectList"]//a/@href').extract()
        for url in se_url:
            yield scrapy.Request(url=url,callback=self.zhongjiang)


    def zhongjiang(self,response):
        # item = response.meta.get('item')
        item = ShuangseqiuItem()
        times = response.xpath('//span[@class="span_right"]/text()').extract_first('')
        hong = ','.join(response.xpath('//div[@class="ball_box01"]/ul//li/text()').extract())[:-3]
        lan = ','.join(response.xpath('//div[@class="ball_box01"]/ul//li/text()').extract())[-2:]

        item['times'] = times
        item['hong'] = hong
        item['lan'] = lan
        yield item

该文件的作用，是定义初始url

第三，pipilines.py

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

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


import pymysql


class ShuangseqiuPipeline(object):

    def __init__(self, host, port, user, pwd, db):
        self.client = pymysql.Connect(host, user, pwd, db, port, charset='utf8')
        self.cursor = self.client.cursor()

    @classmethod
    def from_crawler(cls, crawler):
        host = crawler.settings['MYSQL_HOST']
        port = crawler.settings['MYSQL_PORT']
        user = crawler.settings['MYSQL_USER']
        pwd = crawler.settings['MYSQL_PWD']
        db = crawler.settings['MYSQL_DB']

        return cls(host, port, user, pwd, db)

    def process_item(self, item, spider):
        insert_sql = """
               insert into kaijiang(times,hong,lan)
               VALUE (%s, %s, %s)
        """
        try:
            self.cursor.execute(insert_sql, (item['times'], item['hong'], item['lan']))
            self.client.commit()
        except Exception as err:
            print(err)
            self.client.rollback()
        return item

第二步中parse和zhongjiang方法返回的内容，这里可以获取到，可以在这里将爬取到的内容写到文件中

第四， middlewares.py文件内容如下

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

# Define here the models for your spider middleware
#
# See documentation in:
# https://doc.scrapy.org/en/latest/topics/spider-middleware.html

from scrapy import signals


class ShuangseqiuSpiderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the spider middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_spider_input(self, response, spider):
        # Called for each response that goes through the spider
        # middleware and into the spider.

        # Should return None or raise an exception.
        return None

    def process_spider_output(self, response, result, spider):
        # Called with the results returned from the Spider, after
        # it has processed the response.

        # Must return an iterable of Request, dict or Item objects.
        for i in result:
            yield i

    def process_spider_exception(self, response, exception, spider):
        # Called when a spider or process_spider_input() method
        # (from other spider middleware) raises an exception.

        # Should return either None or an iterable of Response, dict
        # or Item objects.
        pass

    def process_start_requests(self, start_requests, spider):
        # Called with the start requests of the spider, and works
        # similarly to the process_spider_output() method, except
        # that it doesn’t have a response associated.

        # Must return only requests (not items).
        for r in start_requests:
            yield r

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)


class ShuangseqiuDownloaderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the downloader middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_request(self, request, spider):
        # Called for each request that goes through the downloader
        # middleware.

        # Must either:
        # - return None: continue processing this request
        # - or return a Response object
        # - or return a Request object
        # - or raise IgnoreRequest: process_exception() methods of
        #   installed downloader middleware will be called
        return None

    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.

        # Must either;
        # - return a Response object
        # - return a Request object
        # - or raise IgnoreRequest
        return response

    def process_exception(self, request, exception, spider):
        # Called when a download handler or a process_request()
        # (from other downloader middleware) raises an exception.

        # Must either:
        # - return None: continue processing this exception
        # - return a Response object: stops process_exception() chain
        # - return a Request object: stops process_exception() chain
        pass

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)

第五， settings.py文件

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

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

BOT_NAME = 'ShuangSeqiu'

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


# Crawl responsibly by identifying yourself (and your website) on the user-agent
USER_AGENT = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36'

# Obey robots.txt rules
ROBOTSTXT_OBEY = False

# 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://doc.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://doc.scrapy.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'ShuangSeqiu.middlewares.ShuangseqiuSpiderMiddleware': 543,
#}

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

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

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

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://doc.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://doc.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'


MONGODB_HOST = '127.0.0.1'
MONGODB_PORT= 27017
MONGODB_DBNAME = "shuangseqiu"
MONGODB_SHEETNAME= "kaijiang"



#关于数据库的相关配置
MYSQL_HOST = '127.0.0.1'
MYSQL_PORT = 3306
MYSQL_USER = 'root'
MYSQL_PWD = '1'
MYSQL_DB = 'shuangseqiu'

大功告成咯
接下来就启动爬虫吧：

scrapy crawl kaijiang

步骤总结:

爬取数据：
scrapy的基本用法

  1. 通过命令创建项目
    scrapy startproject 项目名称
  2. 用pycharm打开项目
  3. 通过命令创建爬虫
    scrapy genspider 爬虫名称 域名
  4. 配置settings
    robots_obey=False
    Download_delay=0.5
    Cookie_enable=False
  5. 自定义UserAgentMiddleWare
    可以直接粘现成的
    或者自己通过研究源码实现
  6. 开始解析数据
  1. 先大致规划一下需要几个函数
  2. 函数1跳转到函数2使用 yield scrapy.Request(url,callback,meta,dont_filter)
  1. 将数据封装到items,记得yield item
  2. 自定义pipelines将数据存储到数据库/文件中
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