概述
收集所有外部链接的网站爬虫程序流程图
下例是爬取本站python绘制条形图方法代码详解的实例,大家可以参考下。
完整代码:
#! /usr/bin/env python #coding=utf-8 import urllib2 from bs4 import BeautifulSoup import re import datetime import random pages=set() random.seed(datetime.datetime.Now()) #Retrieves a list of all Internal links found on a page def getInternalLinks(bsObj,includeUrl): internalLinks = [] #Finds all links that begin with a "/" for link in bsObj.findAll("a",href=re.compile("^(/|.*"+includeUrl+")")): if link.attrs['href'] is not None: if link.attrs['href'] not in internalLinks: internalLinks.append(link.attrs['href']) return internalLinks #Retrieves a list of all external links found on a page def getExternalLinks(bsObj,excludeUrl): externalLinks = [] #Finds all links that start with "http" or "www" that do #not contain the current URL for link in bsObj.findAll("a",href=re.compile("^(http|www)((?!"+excludeUrl+").)*$")): if link.attrs['href'] is not None: if link.attrs['href'] not in externalLinks: externalLinks.append(link.attrs['href']) return externalLinks def splitAddress(address): addressParts = address.replace("http://","").split("/") return addressParts def getRandomExternalLink(startingPage): html= urllib2.urlopen(startingPage) bsObj = BeautifulSoup(html) externalLinks = getExternalLinks(bsObj,splitAddress(startingPage)[0]) if len(externalLinks) == 0: internalLinks = getInternalLinks(startingPage) return internalLinks[random.randint(0,len(internalLinks)-1)] else: return externalLinks[random.randint(0,len(externalLinks)-1)] def followExternalOnly(startingSite): externalLink=getRandomExternalLink("https://www.oudahe.com/p/44840/") print("Random external link is: "+externalLink) followExternalOnly(externalLink) #Collects a list of all external URLs found on the site allExtLinks=set() allIntLinks=set() def getAllExternalLinks(siteUrl): html=urllib2.urlopen(siteUrl) bsObj=BeautifulSoup(html) internalLinks = getInternalLinks(bsObj,splitAddress(siteUrl)[0]) externalLinks = getExternalLinks(bsObj,splitAddress(siteUrl)[0]) for link in externalLinks: if link not in allExtLinks: allExtLinks.add(link) print(link) for link in internalLinks: if link not in allIntLinks: print("About to get link:"+link) allIntLinks.add(link) getAllExternalLinks(link) getAllExternalLinks("https://www.oudahe.com/p/44840/")
爬取结果如下:
总结
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总结
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