Python爬虫系列之----Scrapy(五)网页提取的三种方式(正则,Beautiful Soup,Lxml)

柔光的暖阳◎ 2022-06-17 03:49 244阅读 0赞

**一、提取方式**

从网页中提取数据有很多方法,概况起来大概有这么三种方式,首先是正则,然后是流行的Beautiful Soup模块,最后是强大的Lxml模块。

1、正则表达式:最原始的方法,通过编写一些正则表达式,然后从HTML/XML中提取数据。

2、Beautiful Soup模块:Beautiful Soup 是一个可以从 HTML 或 XML 文件中提取数据的 Python 库.它能够通过你喜欢的转换器实现惯用的文档导航,查找,修改文档的方式.Beautiful Soup 会帮你节省数小时甚至数天的工作时间。

3、Lxml模块:lxml是基于libxm12这一XML解析库的Python封装,该模块使用C语言编写,解析速读比Beautiful Soup模块快，不过安装更为复杂。

Scrapy使用了一种基于 [XPath][] 和 [CSS][] 表达式机制: [Scrapy Selectors][]。 关于selector和其他提取机制的信息请参考 [Selector文档][Scrapy Selectors]

这里给出XPath表达式的例子及对应的含义:

*  `/html/head/title`: 选择HTML文档中 `<head>` 标签内的 `<title>` 元素
 *  `/html/head/title/text()`: 选择上面提到的 `<title>` 元素的文字
 *  `//td`: 选择所有的 `<td>` 元素
 *  `//div[@class="mine"]`: 选择所有具有 `class="mine"` 属性的 `div` 元素

上边仅仅是几个简单的XPath例子，XPath实际上要比这远远强大的多。 如果您想了解的更多，我们推荐 [这篇XPath教程][XPath 1] 。

为了配合XPath，Scrapy除了提供了 [`Selector`][Selector] 之外，还提供了方法来避免每次从response中提取数据时生成selector的麻烦。

Selector有四个基本的方法(点击相应的方法可以看到详细的API文档):

*  [`xpath()`][xpath]: 传入xpath表达式，返回该表达式所对应的所有节点的selector list列表 。
 *  [`css()`][css]: 传入CSS表达式，返回该表达式所对应的所有节点的selector list列表.
 *  [`extract()`][extract]: 序列化该节点为unicode字符串并返回list。
 *  [`re()`][re]: 根据传入的正则表达式对数据进行提取，返回unicode字符串list列表。

在Shell中尝试Selector选择器

为了介绍Selector的使用方法，接下来我们将要使用内置的 Scrapy shell 。Scrapy Shell需要您预装好IPython(一个扩展的Python终端,可通过命令安装: pip install ipython)。  
  
  
您需要进入项目的根目录，执行下列命令来启动shell:

scrapy shell "http://blog.csdn.net/u011781521/article/details/70182815"

注意:当您在终端运行Scrapy时，请一定记得给url地址加上引号，否则包含参数的url(例如 & 字符)会导致Scrapy运行失败。

shell的输出:

G:\Scrapy_work\myfendo>scrapy shell "http://blog.csdn.net/u011781521/article/details/70182815"
    2017-04-15 21:01:18 [scrapy.utils.log] INFO: Scrapy 1.3.3 started (bot: myfendo)
    2017-04-15 21:01:18 [scrapy.utils.log] INFO: Overridden settings: {'BOT_NAME': 'myfendo', 'DUPEFILTER_CLASS': 'scrapy.dupefilters.BaseDupeFilter', 'LOGSTATS_INTERVAL': 0, 'NEWSPIDER_MODULE': 'myfendo.spiders', 'ROBOTSTXT_OBEY': True, 'SPIDER_MODULES': ['myfendo.spiders']}
    2017-04-15 21:01:18 [scrapy.middleware] INFO: Enabled extensions:
    ['scrapy.extensions.corestats.CoreStats',
     'scrapy.extensions.telnet.TelnetConsole']
    2017-04-15 21:01:19 [scrapy.middleware] INFO: Enabled downloader middlewares:
    ['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
     'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
     'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
     'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
     'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
     'scrapy.downloadermiddlewares.retry.RetryMiddleware',
     'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
     'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
     'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
     'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
     'scrapy.downloadermiddlewares.stats.DownloaderStats']
    2017-04-15 21:01:19 [scrapy.middleware] INFO: Enabled spider middlewares:
    ['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
     'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
     'scrapy.spidermiddlewares.referer.RefererMiddleware',
     'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
     'scrapy.spidermiddlewares.depth.DepthMiddleware']
    2017-04-15 21:01:19 [scrapy.middleware] INFO: Enabled item pipelines:
    []
    2017-04-15 21:01:19 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6023
    2017-04-15 21:01:19 [scrapy.core.engine] INFO: Spider opened
    2017-04-15 21:01:19 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.csdn.net/robots.txt> (referer: None)
    2017-04-15 21:01:19 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.csdn.net/u011781521/article/details/70182815> (referer: None)
    2017-04-15 21:01:20 [traitlets] DEBUG: Using default logger
    2017-04-15 21:01:20 [traitlets] DEBUG: Using default logger
    [s] Available Scrapy objects:
    [s]   scrapy     scrapy module (contains scrapy.Request, scrapy.Selector, etc)
    [s]   crawler    <scrapy.crawler.Crawler object at 0x000002B5B7E512E8>
    [s]   item       {}
    [s]   request    <GET http://blog.csdn.net/u011781521/article/details/70182815>
    [s]   response   <200 http://blog.csdn.net/u011781521/article/details/70182815>
    [s]   settings   <scrapy.settings.Settings object at 0x000002B5B8E1DB38>
    [s]   spider     <DefaultSpider 'default' at 0x2b5b909f358>
    [s] Useful shortcuts:
    [s]   fetch(url[, redirect=True]) Fetch URL and update local objects (by default, redirects are followed)
    [s]   fetch(req)                  Fetch a scrapy.Request and update local objects
    [s]   shelp()           Shell help (print this help)
    [s]   view(response)    View response in a browser
    In [1]:

当shell载入后，您将得到一个包含response数据的本地 response 变量。输入 response.body 将输出response的包体

![20170415210354237][]

输入 response.headers 可以看到response的包头。

![20170415210434394][]

更为重要的是，当输入 response.selector 时， 您将获取到一个可以用于查询返回数据的selector(选择器)， 以及映射到 response.selector.xpath() 、 response.selector.css() 的快捷方法(shortcut): response.xpath() 和 response.css() 。  
  
同时，shell根据response提前初始化了变量 sel 。该selector根据response的类型自动选择最合适的分析规则(XML vs HTML)。

让我们来试试:

In [4]: response.xpath('//title')
    Out[4]: [<Selector xpath='//title' data='<title>Python爬虫系列之----Scrapy(一)爬虫原理 - fe'>]
    
    In [5]: response.xpath('//title').extract()
    Out[5]: ['<title>Python爬虫系列之----Scrapy(一)爬虫原理 - fendo\r\n        - 博客频道 - CSDN.NET</title>']
    
    In [6]: response.xpath('//title/text()')
    Out[6]: [<Selector xpath='//title/text()' data='Python爬虫系列之----Scrapy(一)爬虫原理 - fendo\r\n  '>]
    
    In [7]: response.xpath('//title/text()').extract()
    Out[7]: ['Python爬虫系列之----Scrapy(一)爬虫原理 - fendo\r\n        - 博客频道 - CSDN.NET']

![20170415210906372][]

**二、提取数据**

让我们从返回的response中提取数据，可以结合Firebug来观察HTML源码并确定合适的XPath表达式

**文章的标题:**

response.xpath('//h1/span/a/text()').extract()

![20170415211702713][]

输出的结果为:

![20170415212344328][]

**网页中的链接:**

response.xpath("//span/a[@href='https://scrapy.org/']/text()").extract()

![20170415214000150][]

输出结果为:

![20170415214602308][]

**网页的描述:**

response.xpath("//meta[@name='description']").extract()

![20170415212546453][]

输出结果为:

![20170415212736991][]

**三、使用Item**

Item 对象是自定义的python字典。 您可以使用标准的字典语法来获取到其每个字段的值。(字段即是我们之前用Field赋值的属性):

一般来说，Spider将会将爬取到的数据以 Item 对象返回。所以为了将爬取的数据返回，我们最终的代码将是:

# -*- coding: utf-8 -*-
    import scrapy
    from myfendo.items import MyfendoItem
    
    class MyfendosSpider(scrapy.Spider):
        name = "myfendos"
        allowed_domains = ["csdn.net"]
        start_urls = [
            "http://blog.csdn.net/u011781521/article/details/70182815",
        ]
    
        def parse(self, response):
            item=MyfendoItem()
            item['title']=response.xpath('//h1/span/a/text()')
            item['link']=response.xpath("//span/a[@href='https://scrapy.org/']/text()")
            item['desc']=response.xpath("//meta[@name='description']")
            yield item

现在运行爬虫将会产生 MyfendoItem对象:

G:\Scrapy_work\myfendo>scrapy crawl myfendos
    2017-04-15 21:50:54 [scrapy.utils.log] INFO: Scrapy 1.3.3 started (bot: myfendo)
    2017-04-15 21:50:54 [scrapy.utils.log] INFO: Overridden settings: {'BOT_NAME': 'myfendo', 'NEWSPIDER_MODULE': 'myfendo.spiders', 'ROBOTSTXT_OBEY': True, 'SPIDER_MODULES': ['myfendo.spiders']}
    2017-04-15 21:50:54 [scrapy.middleware] INFO: Enabled extensions:
    ['scrapy.extensions.corestats.CoreStats',
     'scrapy.extensions.telnet.TelnetConsole',
     'scrapy.extensions.logstats.LogStats']
    2017-04-15 21:50:54 [scrapy.middleware] INFO: Enabled downloader middlewares:
    ['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
     'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
     'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
     'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
     'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
     'scrapy.downloadermiddlewares.retry.RetryMiddleware',
     'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
     'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
     'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
     'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
     'scrapy.downloadermiddlewares.stats.DownloaderStats']
    2017-04-15 21:50:54 [scrapy.middleware] INFO: Enabled spider middlewares:
    ['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
     'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
     'scrapy.spidermiddlewares.referer.RefererMiddleware',
     'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
     'scrapy.spidermiddlewares.depth.DepthMiddleware']
    2017-04-15 21:50:54 [scrapy.middleware] INFO: Enabled item pipelines:
    []
    2017-04-15 21:50:54 [scrapy.core.engine] INFO: Spider opened
    2017-04-15 21:50:54 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
    2017-04-15 21:50:54 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6024
    2017-04-15 21:50:55 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.csdn.net/robots.txt> (referer: None)
    2017-04-15 21:50:55 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.csdn.net/u011781521/article/details/70182815> (referer: None)
    2017-04-15 21:50:55 [scrapy.core.scraper] DEBUG: Scraped from <200 http://blog.csdn.net/u011781521/article/details/70182815>
    {'desc': [<Selector xpath="//meta[@name='description']" data='<meta name="description" content="一、Scra'>],
     'link': [<Selector xpath="//span/a[@href='https://scrapy.org/']/text()" data='https://scrapy.org/'>],
     'title': [<Selector xpath='//h1/span/a/text()' data='\r\n        Python爬虫系列之----Scrapy(一)爬虫原理  '>]}
    2017-04-15 21:50:55 [scrapy.core.engine] INFO: Closing spider (finished)
    2017-04-15 21:50:55 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
    {'downloader/request_bytes': 467,
     'downloader/request_count': 2,
     'downloader/request_method_count/GET': 2,
     'downloader/response_bytes': 17315,
     'downloader/response_count': 2,
     'downloader/response_status_count/200': 2,
     'finish_reason': 'finished',
     'finish_time': datetime.datetime(2017, 4, 15, 13, 50, 55, 392037),
     'item_scraped_count': 1,
     'log_count/DEBUG': 4,
     'log_count/INFO': 7,
     'response_received_count': 2,
     'scheduler/dequeued': 1,
     'scheduler/dequeued/memory': 1,
     'scheduler/enqueued': 1,
     'scheduler/enqueued/memory': 1,
     'start_time': datetime.datetime(2017, 4, 15, 13, 50, 54, 786607)}
    2017-04-15 21:50:55 [scrapy.core.engine] INFO: Spider closed (finished)
    
    G:\Scrapy_work\myfendo>

**四、保存爬取到的数据**

最简单存储爬取的数据的方式是使用 [ Feed exports][Feed exports]:

scrapy crawl myfendos -o items.json

输出的结果:

G:\Scrapy_work\myfendo>scrapy crawl myfendos -o items.json
    2017-04-15 22:19:02 [scrapy.utils.log] INFO: Scrapy 1.3.3 started (bot: myfendo)
    2017-04-15 22:19:02 [scrapy.utils.log] INFO: Overridden settings: {'BOT_NAME': 'myfendo', 'FEED_FORMAT': 'json', 'FEED_URI': 'items.json', 'NEWSPIDER_MODULE': 'myfendo.spiders', 'ROBOTSTXT_OBEY': True, 'SPIDER_MODULES': ['myfendo.spiders']}
    2017-04-15 22:19:02 [scrapy.middleware] INFO: Enabled extensions:
    ['scrapy.extensions.corestats.CoreStats',
     'scrapy.extensions.telnet.TelnetConsole',
     'scrapy.extensions.feedexport.FeedExporter',
     'scrapy.extensions.logstats.LogStats']
    2017-04-15 22:19:03 [scrapy.middleware] INFO: Enabled downloader middlewares:
    ['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
     'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
     'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
     'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
     'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
     'scrapy.downloadermiddlewares.retry.RetryMiddleware',
     'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
     'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
     'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
     'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
     'scrapy.downloadermiddlewares.stats.DownloaderStats']
    2017-04-15 22:19:03 [scrapy.middleware] INFO: Enabled spider middlewares:
    ['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
     'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
     'scrapy.spidermiddlewares.referer.RefererMiddleware',
     'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
     'scrapy.spidermiddlewares.depth.DepthMiddleware']
    2017-04-15 22:19:03 [scrapy.middleware] INFO: Enabled item pipelines:
    []
    2017-04-15 22:19:03 [scrapy.core.engine] INFO: Spider opened
    2017-04-15 22:19:03 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
    2017-04-15 22:19:03 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6024
    2017-04-15 22:19:03 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.csdn.net/robots.txt> (referer: None)
    2017-04-15 22:19:04 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.csdn.net/u011781521/article/details/70182815> (referer: None)
    2017-04-15 22:19:04 [scrapy.core.scraper] DEBUG: Scraped from <200 http://blog.csdn.net/u011781521/article/details/70182815>
    {'desc': ['<meta name="description" '
              'content="一、Scrapy简介Scrapy是一个为了爬取网站数据，提取结构性数据而编写的应用框架。 '
              '可以应用在包括数据挖掘，信息处理或存储历史数据等一系列的程序中。Scrapy 使用 '
              'Twisted这个异步网络库来处理网络通讯，架构清晰，并且包含了各种中间件接口，可以灵活的完成各种需求。Scrapy吸引人的地方在于它是一个框架，任何人都可以根据需求方便的修改。它也提供">'],
     'link': ['https://scrapy.org/'],
     'title': ['\r\n        Python爬虫系列之----Scrapy(一)爬虫原理            \r\n        ']}
    2017-04-15 22:19:04 [scrapy.core.engine] INFO: Closing spider (finished)
    2017-04-15 22:19:04 [scrapy.extensions.feedexport] INFO: Stored json feed (1 items) in: items.json
    2017-04-15 22:19:04 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
    {'downloader/request_bytes': 467,
     'downloader/request_count': 2,
     'downloader/request_method_count/GET': 2,
     'downloader/response_bytes': 17313,
     'downloader/response_count': 2,
     'downloader/response_status_count/200': 2,
     'finish_reason': 'finished',
     'finish_time': datetime.datetime(2017, 4, 15, 14, 19, 4, 130548),
     'item_scraped_count': 1,
     'log_count/DEBUG': 4,
     'log_count/INFO': 8,
     'response_received_count': 2,
     'scheduler/dequeued': 1,
     'scheduler/dequeued/memory': 1,
     'scheduler/enqueued': 1,
     'scheduler/enqueued/memory': 1,
     'start_time': datetime.datetime(2017, 4, 15, 14, 19, 3, 323475)}
    2017-04-15 22:19:04 [scrapy.core.engine] INFO: Spider closed (finished)
    
    G:\Scrapy_work\myfendo>

该命令将采用 JSON 格式对爬取的数据进行序列化，生成 items.json 文件。

也可以采用下面的方法保存JSON数据:

**1.修改pipelines.py文件**

from scrapy import signals
    import json
    import codecs
    
    
    class JsonWithEncodingCnblogsPipeline(object):
        def __init__(self):
            self.file = codecs.open('myitems.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()

注意类名为JsonWithEncodingCnblogsPipeline哦！settings.py中会用到

**2.修改settings.py，添加以下两个配置项**

ITEM_PIPELINES = {
        'myfendo.pipelines.JsonWithEncodingCnblogsPipeline': 300,
    }
    LOG_LEVEL = 'INFO'

然后运行爬虫:

scrapy crawl myfendos

输出结果为:

G:\Scrapy_work\myfendo>scrapy crawl myfendos
    2017-04-15 22:24:42 [scrapy.utils.log] INFO: Scrapy 1.3.3 started (bot: myfendo)
    2017-04-15 22:24:42 [scrapy.utils.log] INFO: Overridden settings: {'BOT_NAME': 'myfendo', 'LOG_LEVEL': 'INFO', 'NEWSPIDER_MODULE': 'myfendo.spiders', 'ROBOTSTXT_OBEY': True, 'SPIDER_MODULES': ['myfendo.spiders']}
    2017-04-15 22:24:42 [scrapy.middleware] INFO: Enabled extensions:
    ['scrapy.extensions.corestats.CoreStats',
     'scrapy.extensions.telnet.TelnetConsole',
     'scrapy.extensions.logstats.LogStats']
    2017-04-15 22:24:42 [scrapy.middleware] INFO: Enabled downloader middlewares:
    ['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
     'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
     'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
     'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
     'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
     'scrapy.downloadermiddlewares.retry.RetryMiddleware',
     'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
     'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
     'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
     'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
     'scrapy.downloadermiddlewares.stats.DownloaderStats']
    2017-04-15 22:24:42 [scrapy.middleware] INFO: Enabled spider middlewares:
    ['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
     'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
     'scrapy.spidermiddlewares.referer.RefererMiddleware',
     'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
     'scrapy.spidermiddlewares.depth.DepthMiddleware']
    2017-04-15 22:24:42 [scrapy.middleware] INFO: Enabled item pipelines:
    ['myfendo.pipelines.JsonWithEncodingCnblogsPipeline']
    2017-04-15 22:24:42 [scrapy.core.engine] INFO: Spider opened
    2017-04-15 22:24:42 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
    2017-04-15 22:24:43 [scrapy.core.engine] INFO: Closing spider (finished)
    2017-04-15 22:24:43 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
    {'downloader/request_bytes': 467,
     'downloader/request_count': 2,
     'downloader/request_method_count/GET': 2,
     'downloader/response_bytes': 17315,
     'downloader/response_count': 2,
     'downloader/response_status_count/200': 2,
     'finish_reason': 'finished',
     'finish_time': datetime.datetime(2017, 4, 15, 14, 24, 43, 434983),
     'item_scraped_count': 1,
     'log_count/INFO': 7,
     'response_received_count': 2,
     'scheduler/dequeued': 1,
     'scheduler/dequeued/memory': 1,
     'scheduler/enqueued': 1,
     'scheduler/enqueued/memory': 1,
     'start_time': datetime.datetime(2017, 4, 15, 14, 24, 42, 660934)}
    2017-04-15 22:24:43 [scrapy.core.engine] INFO: Spider closed (finished)
    
    G:\Scrapy_work\myfendo>

会生成一个myitems.json的文件

![20170415222636492][]

完整的示例: [ http://download.csdn.net/detail/u011781521/9815346][http_download.csdn.net_detail_u011781521_9815346]

[XPath]: http://www.w3.org/TR/xpath
[CSS]: http://www.w3.org/TR/selectors
[Scrapy Selectors]: https://docs.scrapy.org/en/latest/topics/selectors.html
[XPath 1]: http://www.w3schools.com/XPath/default.asp
[Selector]: http://scrapy-chs.readthedocs.io/zh_CN/0.24/topics/selectors.html#scrapy.selector.Selector
[xpath]: http://scrapy-chs.readthedocs.io/zh_CN/0.24/topics/selectors.html#scrapy.selector.Selector.xpath
[css]: http://scrapy-chs.readthedocs.io/zh_CN/0.24/topics/selectors.html#scrapy.selector.Selector.css
[extract]: http://scrapy-chs.readthedocs.io/zh_CN/0.24/topics/selectors.html#scrapy.selector.Selector.extract
[re]: http://scrapy-chs.readthedocs.io/zh_CN/0.24/topics/selectors.html#scrapy.selector.Selector.re
[20170415210354237]: /images/20220617/53d60c453901422088ec81a899de98d3.png
[20170415210434394]: /images/20220617/509f674b093c4c4eb8fe4a03836fce71.png
[20170415210906372]: /images/20220617/ec1624ae1b114f1e8829c3fbc4489684.png
[20170415211702713]: /images/20220617/1085e423066543f3b6d4f350ecb12e94.png
[20170415212344328]: /images/20220617/d06fa1eb6dc44d3885746aca7fb6cf95.png
[20170415214000150]: /images/20220617/cb61cfccde7f49b894494484fc225523.png
[20170415214602308]: /images/20220617/75f00a7927d246fe86955282ff63e5f0.png
[20170415212546453]: /images/20220617/e70485c6c86147dcb9fe7c85622de5fb.png
[20170415212736991]: /images/20220617/20f76865b48c4ef4858c189124efb3c0.png
[Feed exports]: https://docs.scrapy.org/en/latest/topics/feed-exports.html
[20170415222636492]: /images/20220617/80459b391c4b47efaac631422543601c.png
[http_download.csdn.net_detail_u011781521_9815346]: http://download.csdn.net/detail/u011781521/9815346