环境:CentOS 6.0 虚拟机
scrapy(如未安装可参考 安装python爬虫scrapy踩过的那些坑和编程外的思考 )
1、创建工程cnblogs
[root@bogon share]# scrapy startproject cnblogs 2015-06-10 15:45:03 [scrapy] INFO: Scrapy 1.0.0rc2 started (bot: scrapybot) 2015-06-10 15:45:03 [scrapy] INFO: Optional features available: ssl, http11 2015-06-10 15:45:03 [scrapy] INFO: Overridden settings: {} New Scrapy project 'cnblogs' created in: /mnt/hgfs/share/cnblogs You can start your first spider with: cd cnblogs scrapy genspider example example.com
2、查看下工程的结构
[root@bogon share]# tree cnblogs/ cnblogs/ ├── cnblogs │ ├── __init__.py │ ├── items.py #用于定义抽取网页结构 │ ├── pipelines.py #将抽取的数据进行处理 │ ├── settings.py #爬虫配置文件 │ └── spiders │ └── __init__.py └── scrapy.cfg #项目配置文件
3、定义抽取cnblogs的网页结构,修改items.py
这里我们抽取四个内容:
[root@bogon cnblogs]# vi cnblogs/items.py # -*- 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 CnblogsItem(scrapy.Item): # define the fields for your item here like: # name = scrapy.Field() title = scrapy.Field() link = scrapy.Field() desc = scrapy.Field() listUrl = scrapy.Field() pass
4、创建spider
[root@bogon cnblogs]# vi cnblogs/spiders/cnblogs_spider.py #coding=utf-8 import re import json from scrapy.selector import Selector try: from scrapy.spider import Spider except: from scrapy.spider import BaseSpider as Spider from scrapy.utils.response import get_base_url from scrapy.utils.url import urljoin_rfc from scrapy.contrib.spiders import CrawlSpider, Rule from scrapy.contrib.linkextractors.sgml import SgmlLinkExtractor as sle from cnblogs.items import * class CnblogsSpider(CrawlSpider): #定义爬虫的名称 name = "CnblogsSpider" #定义允许抓取的域名,如果不是在此列表的域名则放弃抓取 allowed_domains = ["cnblogs.com"] #定义抓取的入口url start_urls = [ "http://www.cnblogs.com/rwxwsblog/default.html?page=1" ] # 定义爬取URL的规则,并指定回调函数为parse_item rules = [ Rule(sle(allow=("/rwxwsblog/default.html/?page=/d{1,}")), #此处要注意?号的转换,复制过来需要对?号进行转义。 follow=True, callback='parse_item') ] #print "**********CnblogsSpider**********" #定义回调函数 #提取数据到Items里面,主要用到XPath和CSS选择器提取网页数据 def parse_item(self, response): #print "-----------------" items = [] sel = Selector(response) base_url = get_base_url(response) postTitle = sel.css('div.day div.postTitle') #print "=============length=======" postCon = sel.css('div.postCon div.c_b_p_desc') #标题、url和描述的结构是一个松散的结构,后期可以改进 for index in range(len(postTitle)): item = CnblogsItem() item['title'] = postTitle[index].css("a").xpath('text()').extract()[0] #print item['title'] + "***************/r/n" item['link'] = postTitle[index].css('a').xpath('@href').extract()[0] item['listUrl'] = base_url item['desc'] = postCon[index].xpath('text()').extract()[0] #print base_url + "********/n" items.append(item) #print repr(item).decode("unicode-escape") + '/n' return items
注意:
首行要设置为: #coding=utf-8 或 # -*- coding: utf-8 -*- 哦!否则会报错。
SyntaxError: Non-ASCII character '/xe5' in file /mnt/hgfs/share/cnblogs/cnblogs/spiders/cnblogs_spider.py on line 15, but no encoding declared; see http://python.org/dev/peps/pep-0263/ for details
spider的名称为: CnblogsSpider ,后面会用到。
5、修改pipelines.py文件
[root@bogon cnblogs]# vi cnblogs/pipelines.py # -*- 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 from scrapy import signals import json import codecs class JsonWithEncodingCnblogsPipeline(object): def __init__(self): self.file = codecs.open('cnblogs.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
6、修改settings.py,添加以下两个配置项
ITEM_PIPELINES = { 'cnblogs.pipelines.JsonWithEncodingCnblogsPipeline': 300, }
LOG_LEVEL = 'INFO'
7、运行spider,scrapy crawl 爬虫名称(cnblogs_spider.py中定义的name)
[root@bogon cnblogs]# scrapy crawl CnblogsSpider
8、查看结果more cnblogs.json(pipelines.py中定义的名称 )
more cnblogs.json
9、如果有需要可以将结果转成txt文本格式,可参考另外一篇文章 python将json格式的数据转换成文本格式的数据或sql文件
源码可在此下载: https://github.com/jackgitgz/cnblogs
10、相信大家还会有疑问,我们能不能将数据直接保存在数据库呢?答案是可以的,接下来的文章会逐一介绍,敬请期待。
参考资料:
http://doc.scrapy.org/en/master/
http://blog.csdn.net/HanTangSongMing/article/details/24454453