面对网络不稳定,页面更新等问题,很可能出现程序异常的问题,所以我们要对程序进行一些异常处理。大家可能觉得处理异常是一个比较麻烦的活,但在面对复杂网页和任务的时候,无疑成为一个很好的代码习惯。
网页‘404'、‘500'等问题
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try :
html = urlopen( 'http://www.pmcaff.com/2221' )
except HTTPError as e:
print (e)
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返回的是空网页
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if html is None :
print ( '没有找到网页' )
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目标标签在网页中缺失
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try :
#不存在的标签
content = bsObj.nonExistingTag.anotherTag
except AttributeError as e:
print ( '没有找到你想要的标签' )
else :
if content = = None :
print ( '没有找到你想要的标签' )
else :
print (content)
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实例
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if sys.version_info[ 0 ] = = 2 :
from urllib2 import HTTPError
else :
from urllib.request import urlopen # Python3
from urllib.error import HTTPError
import sys
def getTitle(url):
try :
html = urlopen(url)
except HTTPError as e:
print (e)
return None
try :
bsObj = BeautifulSoup(html.read())
title = bsObj.body.h1
except AttributeError as e:
return None
return title
title = getTitle( "http://www.pythonscraping.com/exercises/exercise1.html" )
if title = = None :
print ( "Title could not be found" )
else :
print (title)
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以上全部为本篇文章的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://blog.csdn.net/u013007900/article/details/53819711