useragentstring.com 网站几乎廊括了所有的User-Agent，刚学了scrapy，打算那它练手，把上面的 user-agent 爬取下来。

本文只爬取常见的 FireFox, Chrome, Opera, Safri, Internet Explorer

一、创建爬虫项目

1.创建爬虫项目useragent

$ scrapy startproject useragent

2.进入项目目录

$ cd useragent

3.生成爬虫文件 ua

这一步不是必须的，不过有了就方便些

$ scrapy genspider ua useragentstring.com

二、编辑 item 文件

# useragent\items.py

import scrapy

class UseragentItem(scrapy.Item):

    # define the fields for your item here like:

    ua_name = scrapy.Field()

    ua_string = scrapy.Field()

三、编辑爬虫文件

# useragent\spiders\ua.py 

import scrapy

from useragent.items import UseragentItem

class UaSpider(scrapy.Spider):

    name = "ua"

    allowed_domains = ["useragentstring.com"]

    start_urls = (

        'http://www.useragentstring.com/pages/useragentstring.php?name=Firefox',

        'http://www.useragentstring.com/pages/useragentstring.php?name=Internet+Explorer',

        'http://www.useragentstring.com/pages/useragentstring.php?name=Opera',

        'http://www.useragentstring.com/pages/useragentstring.php?name=Safari',

        'http://www.useragentstring.com/pages/useragentstring.php?name=Chrome',

    )

    def parse(self, response):

        ua_name = response.url.splite('=')[-1]

        for ua_string in response.xpath('//li/a/text()').extract():

            item = UseragentItem()

            item['ua_name'] = ua_name

            item['ua_string'] = ua_string.strip()

            yield item

四、运行爬虫

通过参数-o，控制爬虫输出为 json 文件

$ scrapy crawl ua -o item.json

结果如图：

看起来没有得到想要的结果，注意到那个robot.txt。我猜测可能是网站禁止爬虫

猜的对不对先不管，先模拟浏览器再说，给所有的 request 添加 headers:

# useragent\spiders\ua.py 

import scrapy

from useragent.items import UseragentItem

class UaSpider(scrapy.Spider):

    name = "ua"

    allowed_domains = ["useragentstring.com"]

    start_urls = (

        'http://www.useragentstring.com/pages/useragentstring.php?name=Firefox',

        'http://www.useragentstring.com/pages/useragentstring.php?name=Internet+Explorer',

        'http://www.useragentstring.com/pages/useragentstring.php?name=Opera',

        'http://www.useragentstring.com/pages/useragentstring.php?name=Safari',

        'http://www.useragentstring.com/pages/useragentstring.php?name=Chrome',

    )

    # 在所有的请求发生之前执行

    def start_requests(self):

        for url in self.start_urls:

            headers = {"User-Agent": "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; AcooBrowser; .NET CLR 1.1.4322; .NET CLR 2.0.50727)"}

            yield scrapy.Request(url, callback=self.parse, headers=headers)

    def parse(self, response):

        ua_name = response.url.split('=')[-1]

        for ua_string in response.xpath('//li/a/text()').extract():

            item = UseragentItem()

            item['ua_name'] = ua_name

            item['ua_string'] = ua_string.strip()

            yield item

在运行，OK了！

效果图如下：

好了，以后不愁没有 User Agent用了。