爬取伯乐在线文章（一）

Scrapy生成的项目目录

文件说明：

• scrapy.cfg  项目的配置信息，主要为Scrapy命令行工具提供一个基础的配置信息。（真正爬虫相关的配置信息在settings.py文件中）
• items.py    设置数据存储模板，用于结构化数据，如：Django的Model
• pipelines    数据处理行为，如：一般结构化的数据持久化
• settings.py 配置文件，如：递归的层数、并发数，延迟下载等
• spiders      爬虫目录，如：创建文件，编写爬虫规则

注意：一般创建爬虫文件时，以网站域名命名

 jobbole.py

# -*- coding: utf-8 -*-
import scrapy


class JobboleSpider(scrapy.Spider):
    name = 'jobbole'
    #允许的域名
    allowed_domains = ['blog.jobbole.com']
    #起始的url，是一个list，可以放入所有要爬取的URL
    start_urls = ['http://blog.jobbole.com/']

    #业务逻辑
    def parse(self, response):
        pass

设置断点模式

在scrapy.cfg文件同级目录下建立main.py文件，内容如下

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

import sys
import os

from scrapy.cmdline import execute

sys.path.append(os.path.dirname(os.path.abspath(__file__)))
execute(['scrapy', 'crawl', 'jobbole'])

启动爬虫

启动爬虫命令：

scrapy crawl jobbole

(scrapyenv) E:PythonEnvsEnterpriseSpider>scrapy crawl jobbole
2018-11-05 09:03:32 [scrapy.utils.log] INFO: Scrapy 1.5.1 started (bot: EnterpriseSpider)
2018-11-05 09:03:32 [scrapy.utils.log] INFO: Versions: lxml 4.2.5.0, libxml2 2.9.5, cssselect 1.0.3, parsel 1.5.1, w3lib 1.19.0, Twisted 18.9.0, Python 3.6.6 (v3.6.6:4cf1f54eb7, Jun 27 2018, 03:37:03) [MSC v.1900 64 bit (AMD64)], pyOpenSSL 18.0.0 (OpenSSL 1.1.0i  14 Aug 2018), cryptography 2.3.1, Platform Windows-10-10.0.17134-SP0
2018-11-05 09:03:32 [scrapy.crawler] INFO: Overridden settings: {'BOT_NAME': 'EnterpriseSpider', 'NEWSPIDER_MODULE': 'EnterpriseSpider.spiders', 'ROBOTSTXT_OBEY': True, 'SPIDER_MODULES': ['EnterpriseSpider.spiders']}
2018-11-05 09:03:32 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.logstats.LogStats']
Unhandled error in Deferred:
2018-11-05 09:03:32 [twisted] CRITICAL: Unhandled error in Deferred:

Traceback (most recent call last):
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycrawler.py", line 171, in crawl
    return self._crawl(crawler, *args, **kwargs)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycrawler.py", line 175, in _crawl
    d = crawler.crawl(*args, **kwargs)
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternetdefer.py", line 1613, in unwindGenerator
    return _cancellableInlineCallbacks(gen)
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternetdefer.py", line 1529, in _cancellableInlineCallbacks
    _inlineCallbacks(None, g, status)
--- <exception caught here> ---
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternetdefer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycrawler.py", line 80, in crawl
    self.engine = self._create_engine()
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycrawler.py", line 105, in _create_engine
    return ExecutionEngine(self, lambda _: self.stop())
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycoreengine.py", line 69, in __init__
    self.downloader = downloader_cls(crawler)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycoredownloader\__init__.py", line 88, in __init__
    self.middleware = DownloaderMiddlewareManager.from_crawler(crawler)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapymiddleware.py", line 58, in from_crawler
    return cls.from_settings(crawler.settings, crawler)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapymiddleware.py", line 34, in from_settings
    mwcls = load_object(clspath)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapyutilsmisc.py", line 44, in load_object
    mod = import_module(module)
  File "e:pythonenvsscrapyenvlibimportlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import

  File "<frozen importlib._bootstrap>", line 971, in _find_and_load

  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked

  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked

  File "<frozen importlib._bootstrap_external>", line 678, in exec_module

  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed

  File "e:pythonenvsscrapyenvlibsite-packagesscrapydownloadermiddlewares
etry.py", line 20, in <module>
    from twisted.web.client import ResponseFailed
  File "e:pythonenvsscrapyenvlibsite-packages	wistedwebclient.py", line 41, in <module>
    from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternetendpoints.py", line 41, in <module>
    from twisted.internet.stdio import StandardIO, PipeAddress
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternetstdio.py", line 30, in <module>
    from twisted.internet import _win32stdio
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternet\_win32stdio.py", line 9, in <module>
    import win32api
builtins.ModuleNotFoundError: No module named 'win32api'

2018-11-05 09:03:32 [twisted] CRITICAL:
Traceback (most recent call last):
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternetdefer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycrawler.py", line 80, in crawl
    self.engine = self._create_engine()
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycrawler.py", line 105, in _create_engine
    return ExecutionEngine(self, lambda _: self.stop())
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycoreengine.py", line 69, in __init__
    self.downloader = downloader_cls(crawler)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapycoredownloader\__init__.py", line 88, in __init__
    self.middleware = DownloaderMiddlewareManager.from_crawler(crawler)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapymiddleware.py", line 58, in from_crawler
    return cls.from_settings(crawler.settings, crawler)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapymiddleware.py", line 34, in from_settings
    mwcls = load_object(clspath)
  File "e:pythonenvsscrapyenvlibsite-packagesscrapyutilsmisc.py", line 44, in load_object
    mod = import_module(module)
  File "e:pythonenvsscrapyenvlibimportlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "e:pythonenvsscrapyenvlibsite-packagesscrapydownloadermiddlewares
etry.py", line 20, in <module>
    from twisted.web.client import ResponseFailed
  File "e:pythonenvsscrapyenvlibsite-packages	wistedwebclient.py", line 41, in <module>
    from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternetendpoints.py", line 41, in <module>
    from twisted.internet.stdio import StandardIO, PipeAddress
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternetstdio.py", line 30, in <module>
    from twisted.internet import _win32stdio
  File "e:pythonenvsscrapyenvlibsite-packages	wistedinternet\_win32stdio.py", line 9, in <module>
    import win32api
ModuleNotFoundError: No module named 'win32api'

(scrapyenv) E:PythonEnvsEnterpriseSpider>

报错：ModuleNotFoundError: No module named 'win32api'，缺少模块win32pi

安装缺少的模块，使用国内豆瓣源进行加速安装

pip install -i https://pypi.douban.com/simple pypiwin32

再次启动爬虫，运行成功。

(scrapyenv) E:PythonEnvsEnterpriseSpider>scrapy crawl jobbole
2018-11-05 09:13:15 [scrapy.utils.log] INFO: Scrapy 1.5.1 started (bot: EnterpriseSpider)
2018-11-05 09:13:15 [scrapy.utils.log] INFO: Versions: lxml 4.2.5.0, libxml2 2.9.5, cssselect 1.0.3, parsel 1.5.1, w3lib 1.19.0, Twisted 18.9.0, Python 3.6.6 (v3.6.6:4cf1f54eb7, Jun 27 2018, 03:37:03) [MSC v.1900 64 bit (AMD64)], pyOpenSSL 18.0.0 (OpenSSL 1.1.0i  14 Aug 2018), cryptography 2.3.1, Platform Windows-10-10.0.17134-SP0
2018-11-05 09:13:15 [scrapy.crawler] INFO: Overridden settings: {'BOT_NAME': 'EnterpriseSpider', 'NEWSPIDER_MODULE': 'EnterpriseSpider.spiders', 'ROBOTSTXT_OBEY': True, 'SPIDER_MODULES': ['EnterpriseSpider.spiders']}
2018-11-05 09:13:15 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.logstats.LogStats']
2018-11-05 09:13:16 [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.httpproxy.HttpProxyMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2018-11-05 09:13:16 [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']
2018-11-05 09:13:16 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2018-11-05 09:13:16 [scrapy.core.engine] INFO: Spider opened
2018-11-05 09:13:16 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2018-11-05 09:13:16 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6023
2018-11-05 09:13:16 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.jobbole.com/robots.txt> (referer: None)
2018-11-05 09:13:18 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.jobbole.com/> (referer: None)
2018-11-05 09:13:18 [scrapy.core.engine] INFO: Closing spider (finished)
2018-11-05 09:13:18 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 440,
 'downloader/request_count': 2,
 'downloader/request_method_count/GET': 2,
 'downloader/response_bytes': 21847,
 'downloader/response_count': 2,
 'downloader/response_status_count/200': 2,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2018, 11, 5, 1, 13, 18, 465449),
 'log_count/DEBUG': 3,
 '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(2018, 11, 5, 1, 13, 16, 312886)}
2018-11-05 09:13:18 [scrapy.core.engine] INFO: Spider closed (finished)

(scrapyenv) E:PythonEnvsEnterpriseSpider>

在PyCharm中调试爬虫

1.　修改settings.py文件

将ROBOTSTXT_OBEY的值设置为False，否则爬虫会去读取每个网站的robots协议，这样爬虫会很快停止。

2.　在jobbole.py文件设置断点

3.　以Debug模式启动main文件

进入断点，此时查看response，发现传入进来的URL实际上就是starts_urls

查看第一行response，发现类型是HtmlResponse，状态是200，返回成功

_DEFAULT_ENCODING是默认字符集ASCII，

encoding是scrapy设置的字符集UTF-8，

body设要爬取的网站html的源文件，我们实际操作的就是源文件。