scrapy-splash抓取动态数据例子一

　　目前，为了加速页面的加载速度，页面的很多部分都是用JS生成的，而对于用scrapy爬虫来说就是一个很大的问题，因为scrapy没有JS engine，所以爬取的都是静态页面，对于JS生成的动态页面都无法获得

　　解决方案：

　　1、利用第三方中间件来提供JS渲染服务： scrapy-splash 等。

　　2、利用webkit或者基于webkit库

　　Splash是一个Javascript渲染服务。它是一个实现了HTTP API的轻量级浏览器，Splash是用Python实现的，同时使用Twisted和QT。Twisted（QT）用来让服务具有异步处理能力，以发挥webkit的并发能力。

　　

　　下面就来讲一下如何使用scrapy-splash：

　　1、利用pip安装scrapy-splash库：

　　2、pip install scrapy-splash

　　3、安装docker

　　　　scrapy-splash使用的是Splash HTTP API， 所以需要一个splash instance，一般采用docker运行splash，所以需要安装docker，具体参见：http://www.cnblogs.com/shaosks/p/6932319.html

　　4、启动docker

　　　　 安装好后运行docker。docker成功安装后，有“Docker Quickstart Terminal”图标，双击他启动

　　　　

　　5、拉取镜像(pull the image)：　　　

　　　　　$ docker pull scrapinghub/splash

　　　　

　　　　这样就正式启动了。

　　6、用docker运行scrapinghub/splash服务：　　　

　　　$ docker run -p 8050:8050 scrapinghub/splash

　　　　首次启动会比较慢，加载一些东西，多次启动会出现以下信息

　　　　

　　　　这时要关闭当前窗口，然后在进程管理器里面关闭一些进程重新打开

　　　　

　　　　重新打开Docker Quickstart Terminal，然后输入：docker run -p 8050:8050 scrapinghub/splash

　　　　

　　　　

　　　7、配置splash服务（以下操作全部在settings.py）：

　　　　1）添加splash服务器地址：

　　　　

　　　　2）将splash middleware添加到DOWNLOADER_MIDDLEWARE中：

　　　　

　　　　

　　　　3)Enable SplashDeduplicateArgsMiddleware:

　　　　

　　　　4)Set a custom DUPEFILTER_CLASS:

　　　　

　　　　5)a custom cache storage backend:

　　　　

　　　8、正式抓取

　　 　　该例子是抓取京东某个手机产品的详细信息，地址：https://item.jd.com/2600240.html

　　　　 如下图：框住的信息是要榨取的内容

　　　　

　　　　对应的html

　　　　1、京东价：

　　　　

　　　　抓取代码：prices = site.xpath('//span[@class="p-price"]/span/text()')

　　　　2、促销

　　　　

　　　　抓取代码：cxs = site.xpath('//div[@class="J-prom-phone-jjg"]/em/text()')

　　　　3、增值业务

　　　　

　　　　抓取代码：value_addeds =site.xpath('//ul[@class="choose-support lh"]/li/a/span/text()')

　　　　4、重量

　　　　

　　　　抓取代码：quality = site.xpath('//div[@id="summary-weight"]/div[2]/text()')

　　　　5、选择颜色

　　　　

　　　　抓取代码：colors = site.xpath('//div[@id="choose-attr-1"]/div[2]/div/@title')

　　　　6、选择版本

　　　　

　　　　抓取代码：versions = site.xpath('//div[@id="choose-attr-2"]/div[2]/div/@data-value')

　　　　7、购买方式

　　　　

　　　　抓取代码：buy_style = site.xpath('//div[@id="choose-type"]/div[2]/div/a/text()')

　　　　8、套　　装

　　　　

　　　　抓取代码：suits = site.xpath('//div[@id="choose-suits"]/div[2]/div/a/text()')

　　　　9、增值保障

　　　　

　　　　抓取代码：vaps = site.xpath('//div[@class="yb-item-cat"]/div[1]/span[1]/text()')

　　　　10、白条分期

　　　　

　　　　抓取代码：stagings = site.xpath('//div[@class="baitiao-list J-baitiao-list"]/div[@class="item"]/a/strong/text()')

　　　 9、运行splash服务

　　　　　　在抓取之前首先要启动splash服务，命令：docker run -p 8050:8050 scrapinghub/splash，

　　　　 点击“Docker Quickstart Terminal” 图标

　　　　

　　　　10、运行scrapy crawl scrapy_splash

　　　　

　　　　11、抓取数据

　　　　

　　　　

　　　　12、完整源代码

　　　　　　1、SplashSpider

　　　　　　

# -*- coding: utf-8 -*-
import scrapy
from scrapy import Request
from scrapy.spiders import Spider
from scrapy_splash import SplashRequest
from scrapy_splash import SplashMiddleware
from scrapy.http import Request, HtmlResponse
from scrapy.selector import Selector
from scrapy_splash import SplashRequest
from splash_test.items import SplashTestItem
import sys
reload(sys)
sys.setdefaultencoding('utf-8')
sys.stdout = open('output.txt', 'w')

class SplashSpider(Spider):
    name = 'scrapy_splash'
    start_urls = [
        'https://item.jd.com/2600240.html'
    ]

    # request需要封装成SplashRequest
    def start_requests(self):
        for url in self.start_urls:
            yield SplashRequest(url
                                , self.parse
                                , args={'wait': '0.5'}
                                # ,endpoint='render.json'
                                )

    def parse(self, response):

        # 本文只抓取一个京东链接，此链接为京东商品页面，价格参数是ajax生成的。会把页面渲染后的html存在html.txt
        # 如果想一直抓取可以使用CrawlSpider，或者把下面的注释去掉
        site = Selector(response)
        it_list = []
        it = SplashTestItem()
        #京东价
        # prices = site.xpath('//span[@class="price J-p-2600240"]/text()')
        # it['price']= prices[0].extract()
        # print '京东价：'+ it['price']
        prices = site.xpath('//span[@class="p-price"]/span/text()')
        it['price'] = prices[0].extract()+ prices[1].extract()
        print '京东价：' + it['price']

        # 促　　销
        cxs = site.xpath('//div[@class="J-prom-phone-jjg"]/em/text()')
        strcx = ''
        for cx in cxs:
            strcx += str(cx.extract())+' '
        it['promotion'] = strcx
        print '促销:%s '% strcx

        # 增值业务
        value_addeds =site.xpath('//ul[@class="choose-support lh"]/li/a/span/text()')
        strValueAdd =''
        for va in value_addeds:
            strValueAdd += str(va.extract())+' '
        print '增值业务:%s ' % strValueAdd
        it['value_add'] = strValueAdd

        # 重量
        quality = site.xpath('//div[@id="summary-weight"]/div[2]/text()')
        print '重量:%s ' % str(quality[0].extract())
        it['quality']=quality[0].extract()

        #选择颜色
        colors = site.xpath('//div[@id="choose-attr-1"]/div[2]/div/@title')
        strcolor = ''
        for color in colors:
            strcolor += str(color.extract()) + ' '
        print '选择颜色:%s ' % strcolor
        it['color'] = strcolor

        # 选择版本
        versions = site.xpath('//div[@id="choose-attr-2"]/div[2]/div/@data-value')
        strversion = ''
        for ver in versions:
            strversion += str(ver.extract()) + ' '
        print '选择版本:%s ' % strversion
        it['version'] = strversion

        # 购买方式
        buy_style = site.xpath('//div[@id="choose-type"]/div[2]/div/a/text()')
        print '购买方式:%s ' % str(buy_style[0].extract())
        it['buy_style'] = buy_style[0].extract()

        # 套装
        suits = site.xpath('//div[@id="choose-suits"]/div[2]/div/a/text()')
        strsuit = ''
        for tz in suits:
            strsuit += str(tz.extract()) + ' '
        print '套装:%s ' % strsuit
        it['suit'] = strsuit

        # 增值保障
        vaps = site.xpath('//div[@class="yb-item-cat"]/div[1]/span[1]/text()')
        strvaps = ''
        for vap in vaps:
            strvaps += str(vap.extract()) + ' '
        print '增值保障:%s ' % strvaps
        it['value_add_protection'] = strvaps

        # 白条分期
        stagings = site.xpath('//div[@class="baitiao-list J-baitiao-list"]/div[@class="item"]/a/strong/text()')
        strstaging = ''
        for st in stagings:
            ststr =str(st.extract())
            strstaging += ststr.strip() + ' '
        print '白天分期:%s ' % strstaging
        it['staging'] = strstaging

        it_list.append(it)
        return it_list

　　　2、SplashTestItem

　　　　

　　　　

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

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

import scrapy

class SplashTestItem(scrapy.Item):
    #单价
    price = scrapy.Field()
    # description = Field()
    #促销
    promotion = scrapy.Field()
    #增值业务
    value_add = scrapy.Field()
    #重量
    quality = scrapy.Field()
    #选择颜色
    color = scrapy.Field()
    #选择版本
    version = scrapy.Field()
    #购买方式
    buy_style=scrapy.Field()
    #套装
    suit =scrapy.Field()
    #增值保障
    value_add_protection = scrapy.Field()
    #白天分期
    staging = scrapy.Field()
    # post_view_count = scrapy.Field()
    # post_comment_count = scrapy.Field()
    # url = scrapy.Field()

　　　　3、SplashTestPipeline

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

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

class SplashTestPipeline(object):
    def __init__(self):
        # self.file = open('data.json', 'wb')
        self.file = codecs.open(
            'spider.txt', 'w', encoding='utf-8')
        # self.file = codecs.open(
        #     'spider.json', 'w', encoding='utf-8')

    def process_item(self, item, spider):
        line = json.dumps(dict(item), ensure_ascii=False) + "\n"
        self.file.write(line)
        return item

    def spider_closed(self, spider):
        self.file.close()

　　　4、settings.py

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

# Scrapy settings for splash_test project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     http://doc.scrapy.org/en/latest/topics/settings.html
#     http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#     http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
ITEM_PIPELINES = {
        'splash_test.pipelines.SplashTestPipeline':300
        }
BOT_NAME = 'splash_test'

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

SPLASH_URL = 'http://192.168.99.100:8050'
# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'splash_test (+http://www.yourdomain.com)'

# Obey robots.txt rules
ROBOTSTXT_OBEY = True

DOWNLOADER_MIDDLEWARES = {
    'scrapy_splash.SplashCookiesMiddleware': 723,
    'scrapy_splash.SplashMiddleware': 725,
    'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware': 810,
}
SPIDER_MIDDLEWARES = {
    'scrapy_splash.SplashDeduplicateArgsMiddleware': 100,
}
DUPEFILTER_CLASS = 'scrapy_splash.SplashAwareDupeFilter'
HTTPCACHE_STORAGE = 'scrapy_splash.SplashAwareFSCacheStorage'
# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See http://scrapy.readthedocs.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 http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'splash_test.middlewares.SplashTestSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'splash_test.middlewares.MyCustomDownloaderMiddleware': 543,
#}

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

# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
#ITEM_PIPELINES = {
#    'splash_test.pipelines.SplashTestPipeline': 300,
#}

# Enable and configure the AutoThrottle extension (disabled by default)
# See http://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 http://scrapy.readthedocs.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'