首先声明下,这个爬虫采用的框架来自慕课网的一段视频教程http://www.imooc.com/view/563,原来的爬虫是爬取1000个跟python相关的百度百科页面的标题和摘要。经过改造,本文的爬虫是爬取100个人体艺术页面,下载每个页面上的艺术图片,并汇总每个页面及页面上所有艺术图片的链接地址。

该爬虫分为主控程序(spider_mian)、url管理器(url_manager)、html下载器(html_downloader)、html解析器(html_parser)和数据搜集器(html_outputer)5个py文件构成。

主控程序从入口URL开始爬取,调用html下载器下载需要爬取的页面的源码,然后调用html解析器解析页面源码,获取新的URL来充实url管理器,同时获取新的数据交给数据搜集器供其下载和汇总。

废话不多说,直接上源码,首先是主控程序(spider_mian.py),亮点是那个入口URL,低调,那是艺术。

#coding=utf-8
import url_manager, html_downloader, html_parser, html_outputer

class SpiderMain(object):
    def __init__(self):
        self.urls = url_manager.UrlManager()
        self.downloader = html_downloader.HtmlDownloader()
        self.parser = html_parser.HtmlParser()
        self.outputer = html_outputer.HtmlOutputer()
    
    def craw(self, root_url):
        self.urls.add_new_url(root_url)
        count = 1
        while self.urls.has_new_url():
            try:
                new_url = self.urls.get_new_url()
                print "craw %d : %s" %(count,new_url)
                html_cont = self.downloader.download(new_url)
                new_urls, new_data = self.parser.parse(new_url,html_cont)
                self.urls.add_new_urls(new_urls)
                self.outputer.collect_data(new_data)
                if count == 100:
                    break
                count = count + 1
            except:
                print "craw failed"
            
        self.outputer.output_html()

if __name__=="__main__":
    root_url = "http://www.1000rtrt.com/"
    obj_spider = SpiderMain()
    obj_spider.craw(root_url)

接下来是url管理器(url_manager.py):

#coding=utf-8

class UrlManager(object):
    def __init__(self):
        self.new_urls = set()
        self.old_urls = set()
    
    def add_new_url(self, url):
        if url is None:
            return
        if url not in self.new_urls and url not in self.old_urls:
            self.new_urls.add(url)
            
    def add_new_urls(self, urls):
        if urls is None or len(urls) == 0:
            return
        for url in urls:
            self.add_new_url(url)
    
    def has_new_url(self):
        return len(self.new_urls) != 0

    
    def get_new_url(self):
        new_url = self.new_urls.pop()
        self.old_urls.add(new_url)
        return new_url

以上两段程序基本与慕课网讲的源代码一致,感觉无可挑剔,所以没啥可改的。接下来是html下载器(html_downloader.py),在原课程代码基础上加入了user_agent,伪装成浏览器,以便更顺利地访问网站。

#coding=utf-8
import urllib2
class HtmlDownloader(object):
def download(self,url): if url is None: return None user_agent = 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)' headers = { 'User-Agent' : user_agent } request = urllib2.Request(url,headers = headers) response = urllib2.urlopen(request) if response.getcode() != 200: return None return response.read()

接下来是html解析器(html_parser.py),要想针对具体应用做相应的爬虫,这里是重点需要改的地方,在本文的爬虫中,我们想要把每个页面中的需要下载的照片的链接地址找到。直接上代码:

#coding=utf-8
from bs4 import BeautifulSoup
import re
import urlparse
import urllib2

class HtmlParser(object):
    
    def _get_new_urls(self, page_url, soup):
        new_urls = set()
        links = soup.find_all('a', href=re.compile(r"News/\d+/\d+\.htm"))
        for link in links:
            new_url = link['href']
            new_full_url = urlparse.urljoin(page_url,new_url)
            new_urls.add(new_full_url)
        return new_urls
    
    def _get_new_data(self, page_url, soup):
        res_data = {}
        res_data['url'] = page_url
        res_data['pic'] = []
        nodes = soup.find_all('img')
        for node in nodes:
            if node.attrs.has_key('src'):
                src = node.get('src')
                if src[0:4]=='http':
                    res_data['pic'].append(src)
        return res_data
    
    def parse(self, page_url, html_cont):
        if page_url is None or html_cont is None:
            return
        soup = BeautifulSoup(html_cont,'html.parser',from_encoding='utf-8')
        new_urls = self._get_new_urls(page_url, soup)
        new_data = self._get_new_data(page_url, soup)
        return new_urls,new_data

最后就是数据收集器(html_outputer.py)啦,采用边爬取边下载的步骤,所以将下载图片放在collect_data函数中。

#coding=utf-8
import urllib
import os
class HtmlOutputer(object):
    def __init__(self):
        self.datas = []
    
    def collect_data(self,data):
        if data is None:
            return
        self.datas.append(data)
        path = data['url'].replace(r'/','').replace(':','')
        os.mkdir(path)
        x=0
        for pic in data['pic']:
            urllib.urlretrieve(pic,os.path.join(path,'%s.jpg'%x))
            x+=1

    
    def output_html(self):
        fout = open('output.txt','w')
        for data in self.datas:
            fout.write("%s\n" %data['url'])
            for pic in data['pic']:
                fout.write("%s\n"%pic)

编写完成,可以运行啦。运行主控程序spider_mian.py:

批量下载xx艺术照片的简单爬虫

有的页面爬取失败,是因为个别图片没下载下来导致的。

爬取并下载100个页面的所有图片还是需要点时间的,耐心等待,或者把100改成更小的数目。

成果:

批量下载xx艺术照片的简单爬虫

文件夹里面的东西就不在这里展示了,少儿不宜。