爬蟲利器Scrapy框架：3:創建工程並運行爬蟲

在上一篇文章中我們介紹了在不必創建工程的方式在Scrapy框架下運行爬蟲應用的方法，這篇文章繼續使用相同的示例來介紹一下創建爬蟲工程並運行的方法。

步驟1: 創建爬蟲工程

執行如下命令創建爬蟲工程

執行命令：scrapy startproject 工程名稱

此處創建以webspider爲名稱的爬蟲工程

liumiaocn:~ liumiao$ scrapy startproject webspider
New Scrapy project 'webspider', using template directory '/usr/local/lib/python3.7/site-packages/scrapy/templates/project', created in:
    /Users/liumiao/webspider

You can start your first spider with:
    cd webspider
    scrapy genspider example example.com
liumiaocn:~ liumiao$

工程框架

缺省創建的工程框架信息如下所示：

liumiaocn:~ liumiao$ cd webspider/
liumiaocn:webspider liumiao$ ls
scrapy.cfg	webspider
liumiaocn:webspider liumiao$ tree .
.
├── scrapy.cfg
└── webspider
    ├── __init__.py
    ├── __pycache__
    ├── items.py
    ├── middlewares.py
    ├── pipelines.py
    ├── settings.py
    └── spiders
        ├── __init__.py
        └── __pycache__

4 directories, 7 files
liumiaocn:webspider liumiao$ 

步驟2: 創建爬蟲

Scrapy框架提供了很多功能用於更好地創建和使用爬蟲應用，本文主要爲了說明這種方式下爬蟲應用從創建到使用的過程，我們這裏還繼續使用之前創建簡單的爬蟲應用進行說明, 在spiders目錄下創建如下爬蟲文件

liumiaocn:webspider liumiao$ ls
scrapy.cfg	webspider
liumiaocn:webspider liumiao$ cd webspider/spiders/
liumiaocn:spiders liumiao$ ls
__init__.py	__pycache__
liumiaocn:spiders liumiao$ vi myspider.py
liumiaocn:spiders liumiao$ cat myspider.py 
import scrapy

class MySpider(scrapy.Spider):
    name = 'myspider'
    start_urls = ['https://scrapy.org/']

    def parse(self, response):
        for title in response.css('title'):
            yield {'title': title.get()}
liumiaocn:spiders liumiao$

步驟3: 檢查爬蟲

缺省方式下在spiders下創建的爬蟲可以使用如下命令進行檢查

執行命令：scrapy list

liumiaocn:spiders liumiao$ scrapy list
myspider
liumiaocn:spiders liumiao$ 

步驟4: 運行爬蟲

使用如下命令即可運行爬蟲

執行命令：scrapy crawl 爬蟲名稱

執行示例如下所示：

liumiaocn:spiders liumiao$ scrapy crawl myspider
2020-03-28 07:15:42 [scrapy.utils.log] INFO: Scrapy 2.0.1 started (bot: webspider)
2020-03-28 07:15:42 [scrapy.utils.log] INFO: Versions: lxml 4.5.0.0, libxml2 2.9.10, cssselect 1.1.0, parsel 1.5.2, w3lib 1.21.0, Twisted 20.3.0, Python 3.7.5 (default, Nov  1 2019, 02:16:32) - [Clang 11.0.0 (clang-1100.0.33.8)], pyOpenSSL 19.1.0 (OpenSSL 1.1.1d  10 Sep 2019), cryptography 2.8, Platform Darwin-19.2.0-x86_64-i386-64bit
2020-03-28 07:15:42 [scrapy.utils.log] DEBUG: Using reactor: twisted.internet.selectreactor.SelectReactor
2020-03-28 07:15:42 [scrapy.crawler] INFO: Overridden settings:
{'BOT_NAME': 'webspider',
 'NEWSPIDER_MODULE': 'webspider.spiders',
 'ROBOTSTXT_OBEY': True,
 'SPIDER_MODULES': ['webspider.spiders']}
2020-03-28 07:15:42 [scrapy.extensions.telnet] INFO: Telnet Password: c84dc6ab9f452e91
2020-03-28 07:15:42 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.memusage.MemoryUsage',
 'scrapy.extensions.logstats.LogStats']
2020-03-28 07:15:42 [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.httpproxy.HttpProxyMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2020-03-28 07:15:42 [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']
2020-03-28 07:15:42 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2020-03-28 07:15:42 [scrapy.core.engine] INFO: Spider opened
2020-03-28 07:15:42 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2020-03-28 07:15:42 [scrapy.extensions.telnet] INFO: Telnet console listening on 127.0.0.1:6023
2020-03-28 07:15:43 [scrapy.core.engine] DEBUG: Crawled (403) <GET https://scrapy.org/robots.txt> (referer: None)
2020-03-28 07:15:43 [protego] DEBUG: Rule at line 6 without any user agent to enforce it on.
2020-03-28 07:15:43 [protego] DEBUG: Rule at line 7 without any user agent to enforce it on.
2020-03-28 07:15:43 [protego] DEBUG: Rule at line 8 without any user agent to enforce it on.
2020-03-28 07:15:43 [protego] DEBUG: Rule at line 9 without any user agent to enforce it on.
2020-03-28 07:15:43 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://scrapy.org/> (referer: None)
2020-03-28 07:15:43 [scrapy.core.scraper] DEBUG: Scraped from <200 https://scrapy.org/>
{'title': '<title>Scrapy | A Fast and Powerful Scraping and Web Crawling Framework</title>'}
2020-03-28 07:15:43 [scrapy.core.engine] INFO: Closing spider (finished)
2020-03-28 07:15:43 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 430,
 'downloader/request_count': 2,
 'downloader/request_method_count/GET': 2,
 'downloader/response_bytes': 15996,
 'downloader/response_count': 2,
 'downloader/response_status_count/200': 1,
 'downloader/response_status_count/403': 1,
 'elapsed_time_seconds': 1.268314,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2020, 3, 27, 23, 15, 43, 636638),
 'item_scraped_count': 1,
 'log_count/DEBUG': 7,
 'log_count/INFO': 10,
 'memusage/max': 50221056,
 'memusage/startup': 50221056,
 'response_received_count': 2,
 'robotstxt/request_count': 1,
 'robotstxt/response_count': 1,
 'robotstxt/response_status_count/403': 1,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'start_time': datetime.datetime(2020, 3, 27, 23, 15, 42, 368324)}
2020-03-28 07:15:43 [scrapy.core.engine] INFO: Spider closed (finished)
liumiaocn:spiders liumiao$ 

從結果中，我們可以看到如下的內容

{'title': '<title>Scrapy | A Fast and Powerful Scraping and Web Crawling Framework</title>'}

說明使用此種方式獲取頁面標題已經成功。