Python爬虫获取整个站点中的所有外部链接代码示例
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("/post/130968.htm")
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("/post/130968.htm")
爬取结果如下：
总结
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