Python 网站爬虫开发实践

webside_parser

1.环境依赖

python 2.7

2.目录结构

1. html_downloader 用于html下载
2. html_parser 用于解析html返回对应数据，这里用的pyQuery这个库，类jQuery语法，方便实用
3. outputer 结果输出
4. url_manager url管理
5. main程序入口

3. 主要实现

# -*- conding:utf-8 -*-
from com import url_manager,html_downloader,html_parser,outputer
class HtmlScheduler(object):
    def __init__(self):
        self.urls = url_manager.UrlManager()
        self.downloader = html_downloader.HtmlDownloader()
        self.parser = html_parser.HtmlParser()
        self.outputer = outputer.Outputer()
        pass

    def parse(self):
        new_url = self.urls.get_new_url()
        if new_url!=None:
            html = self.downloader.download(new_url)
            new_urls,new_content = self.parser.parse(html)
            self.urls.add_new_urls(new_urls);
            if new_content!=None:
                self.outputer.collect_data(new_content)
        pass

    def start_parse(self,count):
        self.urls.add_new_url(root_url)
        try:
            while self.urls.has_new_url() and count>0:
                self.parse()
                count = count - 1;
        except:
            print 'error'
        finally:
            self.outputer.output()
        print 'success'
        print 'new urls:%s' % self.urls.new_urls
        print 'old urls:%s' % self.urls.old_urls
        pass

if __name__=='__main__':
    root_url = 'https://www.imooc.com/course/list'
    html_scheduler = HtmlScheduler()
    html_scheduler.start_parse(20) 

from pyquery import PyQuery as pq
class HtmlParser(object):

    def __init__(self):
        self.links_a = []
        self.links_image = []
        pass

    def parse(self,content):
        doc = pq(content)
        for a in doc('.text-page-tag').items():
            href = a.attr('href')
            if href!=None:
                self.links_a.append(href)
        for image in doc('.course-banner').items():
            src = image.attr('data-original')
            alt = image.closest('.course-card').find('.course-card-content h3').text()
            if src!=None:
                self.links_image.append((alt,src))
        return self.links_a,self.links_image
        pass
import urllib2
UA = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36'
class HtmlDownloader(object):

    def __init__(self):
        pass

    def download(self,url):
        request = urllib2.Request(url)
        request.add_header('user-agent', UA)
        response = urllib2.urlopen(request)
        content = response.read();
        return content
        pass

import urllib
class Outputer(object):

    def __init__(self):
        self.data = []
        pass

    def collect_data(self,data):
        if data!=None:
            for item in data:
                self.data.append(item)
        pass

    def output(self):
        x = 0
        for item in self.data:
            if item[1]!=None:
                print 'output image:%s' % item[0]
                try:
                    urllib.urlretrieve('http:'+item[1], 'D:\\parser_pics\%s.jpg' % item[0])
                except:
                    print 'output image %s error' % item[1]  
                x = x+1
        pass
class UrlManager(object):

    def __init__(self):
        self.new_urls = set()
        self.old_urls = set()
        pass

    def has_new_url(self):
        return len(self.new_urls)!=0

    def add_new_url(self,url):
        if url!=None and '/course/list' in url and not url in self.old_urls:
            if 'https://' in url:
                self.new_urls.add(url)
            else:
                self.new_urls.add('https://www.imooc.com'+url)
        pass

    def add_new_urls(self,urls):
        for url in urls:
            if url!=None:
                self.add_new_url(url)
        pass

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

4. 说明

这个爬虫和上一篇文章的爬虫输出结果一样，只不过是python实现的,今天就写到这吧，马上要上班开工了~~