Python爬虫，爬取百度百科词条

我不是女神ヾ 2022-06-09 10:24 429阅读 0赞

看了慕课网的一个网络爬虫教程。模仿着写了一个简单的爬取百度百科的例子。

（1）安装Beautifulsoup4

> Beautifulsoup是Python的一个网页解析库，使用起来很方便。http://cuiqingcai.com/1319.html这个链接是介绍如何使用。这个库是需要安装的，进入Pthon安装目录下面的Scripts目录，执行pip install beautifulsoup进行安装。

> ![20170903200609957][]

（2）爬虫具体实现

爬虫分为5个模块，调度模块、网页下载模块、网页解析模块、URL管理模块、输出模块。

![20170903203201210][]

URL管理模块，负责保存最新的网页URL，每次取出最新的URL进行爬取。

#coding=utf8
    class UrlManager(object):
    
    
        def __init__(self):
            self.new_urls = set()
            self.old_urls = set()
    
    
        #添加新的url
        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)
    
        #批量添加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)
    
        #是否有新的url
        def has_new_url(self):
            return len(self.new_urls) != 0
    
        #获取新的url
        def get_new_url(self):
            new_url = self.new_urls.pop()
            self.old_urls.add(new_url)
    
            return new_url

URL下载模块，负责把网页的内容下载下来，使用urllib2库进行下载。

#coding utf8
    
    import urllib2
    
    
    class HtmlDownloader(object):
    
        def download(self, url):
            if url is None:
                return None
    
            response = urllib2.urlopen(url);
    
            if response.getcode == 200:
                return None
    
            return response.read()

URL解析模块，使用Beautifulsoup把当前网页的其他链接和网页简介解析出来。

# coding:utf-8
    import urlparse
    
    from bs4 import BeautifulSoup
    import re
    
    
    class HtmlParser(object):
        def parser(self, page_url, html_content):
            if page_url is None or html_content is None:
                return
            soup = BeautifulSoup(html_content, "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
    
        def _get_new_urls(self, page_url, soup):
            new_urls = set()
    
            links = soup.find_all('a', href=re.compile(r'/item/'))
    
            for link in links:
                new_url = link["href"]
                new_url_full = urlparse.urljoin(page_url, new_url)
                new_urls.add(new_url_full)
    
            return new_urls
    
        def _get_new_data(self, page_url, soup):
            res_data = {}
    
            res_data['url'] = page_url
    
            # <dd class="lemmaWgt-lemmaTitle-title"> <h1>Python</h1>
            title_node = soup.find('dd', class_="lemmaWgt-lemmaTitle-title").find('h1')
            res_data['title'] = title_node.get_text()
    
            # <div class="lemma-summary" label-module="lemmaSummary">
            summary_node = soup.find("div", class_="lemma-summary")
            res_data['summary'] = summary_node.get_text()
    
            return res_data

输出模块，负责把解析的网页内容保存起来。

#coding=utf-8
    
    class HtmlOutputer(object):
    
        def __init__(self):
            self.datas = []
    
        def collect_data(self,data):
            if data is None:
                return
    
            self.datas.append(data)
    
    
        def outpute_html(self):
            fout = open("outputer.html",'w')
            fout.write("<html>")
            fout.write("<body>")
            fout.write("<table>")
    
    
            for data in self.datas:
                fout.write("<tr>")
                fout.write("<td>%s<td>" % data['url'])
                fout.write("<td>%s<td>" % data['title'].encode('utf-8'))
                fout.write("<td>%s<td>" % data['summary'].encode('utf-8'))
                fout.write("</tr>")
    
            fout.write("</html>")
            fout.write("</body>")
            fout.write("</table>")

最后是调度模块，把各个模块之间的功能调度起来

#coding:utf8
    import url_manager
    import html_downloader
    import html_outputer
    import html_parser
    
    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()
        pass
    
        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 new_url
    
                    #得到url的内容
                    html_content = self.downloader.download(new_url)
    
                    #得到url的内容和url
                    new_urls,new_data = self.parser.parser(new_url,html_content)
    
                    self.urls.add_new_urls(new_urls)
    
                    self.outputer.collect_data(new_data)
                except:
                    print "splider failed"
    
                if (count == 10):
                    break
    
                count = count + 1;
    
            self.outputer.outpute_html()
    
    
    if __name__ == "__main__":
        root_url = "https://baike.baidu.com/item/Python/407313"
    
        obj_splider = SpiderMain()
        obj_splider.craw(root_url)

工程目录如下：

![20170903203835454][]

源码路径如下，感兴趣的朋友可以去下载：

[https://github.com/HelloKittyNII/Spider/tree/master/%E7%99%BE%E5%BA%A6%E7%99%BE%E7%A7%91%E7%88%AC%E8%99%AB/baike\_spider][https_github.com_HelloKittyNII_Spider_tree_master_E7_99_BE_E5_BA_A6_E7_99_BE_E7_A7_91_E7_88_AC_E8_99_AB_baike_spider]

[20170903200609957]: /images/20220609/8684d668d2da4f8e927aaf26e7a64133.png
[20170903203201210]: /images/20220609/00fe5b457d1e4427847b6ce37440b67f.png
[20170903203835454]: /images/20220609/b749a87814fe49919a02ce888ecefbb8.png
[https_github.com_HelloKittyNII_Spider_tree_master_E7_99_BE_E5_BA_A6_E7_99_BE_E7_A7_91_E7_88_AC_E8_99_AB_baike_spider]: https://github.com/HelloKittyNII/Spider/tree/master/%E7%99%BE%E5%BA%A6%E7%99%BE%E7%A7%91%E7%88%AC%E8%99%AB/baike_spider