34.scrapy解决爬虫翻页问题

这里主要解决的问题：

1.翻页需要找到页面中加载的两个参数。

  '__VIEWSTATE': '{}'.format(response.meta['data']['__VIEWSTATE']),

  '__EVENTVALIDATION': '{}'.format(response.meta['data']['__EVENTVALIDATION']),

还有一点需要注意的就是  dont_filter=False

yield scrapy.FormRequest(url=response.url, callback=self.parse, formdata=data, method="POST", dont_filter=False)

2.日期 我自己做的时候取的是2008-2018年的数据。
3.还有的就是数据字段入库乱的问题。
4.一些问题比如越界等，我都没做具体的解决只是做了一个抛出异常没做处理。

这个相对较麻烦一点，首先先分析一下网站，地址:  http://www.nbzj.net/MaterialPriceList.aspx (宁波造价网) 这里呢我主要是拿这个材料信息价数据。

nbzj.py

# -*- coding: utf-8 -*-
import scrapy
import re
from nbzj_web.items import NbzjWebItem

class NbzjSpider(scrapy.Spider):
    name = 'nbzj'
    allowed_domains = ['www.nbzj.net']
    start_urls = ['http://www.nbzj.net/MaterialPriceList.aspx']
    custom_settings = {
        "DOWNLOAD_DELAY": 1,
        "ITEM_PIPELINES": {
            'nbzj_web.pipelines.MysqlPipeline': 300,
        },
        "DOWNLOADER_MIDDLEWARES": {
            'nbzj_web.middlewares.NbzjWebDownloaderMiddleware': 500,
        },
    }
    def parse(self, response):
        _response=response.text
        # print(_response)

        #获取翻页参数
        __VIEWSTATE=re.findall(r'id="__VIEWSTATE" value="(.*?)" />',_response)

        A=__VIEWSTATE[0]
        # print(A)
        __EVENTVALIDATION=re.findall(r'id="__EVENTVALIDATION" value="(.*?)" />',_response)
        B=__EVENTVALIDATION[0]
        # print(B)

        #页码
        page_num=re.findall(r'>下页</a><a title="转到第(.*?)页"',_response)
        # print(page_num[0])
        max_page=page_num[0]
        # print(max_page)

        content={
            '__VIEWSTATE':A,
            '__EVENTVALIDATION':B,
            'page_num':max_page,
        }

        # 获取标签列表

        tag_list=response.xpath("//div[@class='fcon']/table[@class='mytable']//tr/td").extract()
        # print(tag_list)
　　　　  #这里我直接取文本出现问题，我就直接拿标签数据等下面在做字符串的修改删除
        list=[]
        try:
            tag1=tag_list[:9]
            list.append(tag1)
            tag2=tag_list[9:18]
            list.append(tag2)
            tag3=tag_list[18:27]
            list.append(tag3)
            tag4=tag_list[27:36]
            list.append(tag4)
            tag5=tag_list[36:45]
            list.append(tag5)
            tag6=tag_list[45:54]
            list.append(tag6)
            tag7=tag_list[54:63]
            list.append(tag7)
            tag8=tag_list[63:72]
            list.append(tag8)
            tag9=tag_list[72:81]
            list.append(tag9)
            tag10=tag_list[81:90]
            list.append(tag10)
            tag11=tag_list[99:108]
            list.append(tag11)
            tag12=tag_list[108:117]
            list.append(tag12)
            tag13=tag_list[117:126]
            list.append(tag13)
            tag14=tag_list[126:135]
            list.append(tag14)
            tag15=tag_list[135:144]
            list.append(tag15)

            print(list)

            for tag in list:

                item=NbzjWebItem()
                # print(tag)
                #代码
                code=tag[0].replace('<td style="text-align: center">','').replace('</td>','')
                # print(code)
                item['code']=code
                #名称
                name=tag[1].replace('<td>','').replace('</td>','')
                # print(name)
                item['name']=name
                #地区
                district=tag[2].replace('<td style="text-align: center">','').replace('</td>','')
                # print(district)
                item['district']=district
                #型号规格
                _type=tag[3].replace('<td>','').replace('</td>','')
                # print(_type)
                item['_type']=_type
                #单位
                unit=tag[4].replace('<td style="text-align: center">','').replace('</td>','')
                # print(unit)
                item['unit']=unit
                #除税价
                except_tax_price = tag[5].replace('<td style="text-align: right">','').replace('</td>','')
                # print(except_tax_price)
                item['except_tax_price']=except_tax_price
                #含税价
                tax_price = tag[6].replace('<td style="text-align: right">','').replace('</td>','')
                # print(tax_price)
                item['tax_price']=tax_price
                #时间
                time=tag[7].replace('<td style="text-align: center">','').replace('</td>','')
                print(time)
                item['time']=time

                # print('-'*100)
                yield item
            # print('*'*100)
        except:
            pass

        yield scrapy.Request(url=response.url,callback=self.parse_detail,meta={"data": content})

    def parse_detail(self,response):
        for h in range(2008,2019):
            list=['','','','','','','','','','','','']
            for j in list:
                try:
                    max_page=response.meta['data']['page_num']
                    # print(max_page)
                    for i in range(2,int(max_page)):
                        data={

                        '__VIEWSTATE': '{}'.format(response.meta['data']['__VIEWSTATE']),
                        '__VIEWSTATEGENERATOR': 'E53A32FA',
                        '__EVENTTARGET': 'ctl00$ContentPlaceContent$Pager',
                        '__EVENTARGUMENT':'{}'.format(i),
                        '__EVENTVALIDATION': '{}'.format(response.meta['data']['__EVENTVALIDATION']),
                        'HeadSearchType': 'localsite',
                        'ctl00$ContentPlaceContent$txtnewCode':'',
                        'ctl00$ContentPlaceContent$txtMaterualName':'',
                        'ctl00$ContentPlaceContent$ddlArea':'',
                        'ctl00$ContentPlaceContent$txtPublishDate': '{} - 0{}'.format(h,j),
                        'ctl00$ContentPlaceContent$ddlCategoryOne':'',
                        'ctl00$ContentPlaceContent$hidCateId':'',
                        'ctl00$ContentPlaceContent$txtSpecification':'',
                        'ctl00$ContentPlaceContent$Pager_input': '{}'.format(i-1),
                        'ctl00$foot$ddlsnzjw': '',
                        'ctl00$foot$ddlswzjw': '',
                        'ctl00$foot$ddlqtxgw': ''
                        }
                        yield scrapy.FormRequest(url=response.url, callback=self.parse, formdata=data, method="POST", dont_filter=False)
                except:
                    pass

items.py

# -*- 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 NbzjWebItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()

    code=scrapy.Field()
    name=scrapy.Field()
    district=scrapy.Field()
    _type=scrapy.Field()
    unit=scrapy.Field()
    except_tax_price=scrapy.Field()
    tax_price =scrapy.Field()
    time=scrapy.Field()

middlewares.py

# -*- 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 NbzjWebSpiderMiddleware(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 NbzjWebDownloaderMiddleware(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)

piplines.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

# -*- coding: utf-8 -*-
from scrapy.conf import settings
import pymysql

class NbzjWebPipeline(object):
    def process_item(self, item, spider):
        return item

# 数据保存mysql
class MysqlPipeline(object):

    def open_spider(self, spider):
        self.host = settings.get('MYSQL_HOST')
        self.port = settings.get('MYSQL_PORT')
        self.user = settings.get('MYSQL_USER')
        self.password = settings.get('MYSQL_PASSWORD')
        self.db = settings.get(('MYSQL_DB'))
        self.table = settings.get('TABLE')
        self.client = pymysql.connect(host=self.host, user=self.user, password=self.password, port=self.port, db=self.db, charset='utf8')

    def process_item(self, item, spider):
        item_dict = dict(item)
        cursor = self.client.cursor()
        values = ','.join(['%s'] * len(item_dict))
        keys = ','.join(item_dict.keys())
        sql = 'INSERT INTO {table}({keys}) VALUES ({values})'.format(table=self.table, keys=keys, values=values)
        try:
            if cursor.execute(sql, tuple(item_dict.values())):  # 第一个值为sql语句第二个为 值 为一个元组
                print('数据入库成功!')
                self.client.commit()
        except Exception as e:
            print(e)

            print('数据已存在!')
            self.client.rollback()
        return item

    def close_spider(self, spider):

        self.client.close()

setting.py

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

# Scrapy settings for nbzj_web 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 = 'nbzj_web'

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

# mysql配置参数
MYSQL_HOST = "172.16.10.197"
MYSQL_PORT = 3306
MYSQL_USER = "root"
MYSQL_PASSWORD = ""
MYSQL_DB = 'web_datas'
TABLE = "web_nbzj"

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

# 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 = {
#    'nbzj_web.middlewares.NbzjWebSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See https://doc.scrapy.org/en/latest/topics/downloader-middleware.html
DOWNLOADER_MIDDLEWARES = {
   'nbzj_web.middlewares.NbzjWebDownloaderMiddleware': 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 = {
   'nbzj_web.pipelines.NbzjWebPipeline': 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'

scrapy crawl nbzj   执行结果如下

由于设置deloy为 1s 所以速度会比较慢，采集237142条数据。