Python爬虫包BeautifulSoup异常处理（二）

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

try:    html = urlopen('http://www.pmcaff.com/2221')  except HTTPError as e:    print(e)

返回的是空网页

if html is None:    print('没有找到网页')

目标标签在网页中缺失

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)

实例

if sys.version_info[0] == 2:  from urllib2 import urlopen # Python 2  from urllib2 import HTTPErrorelse:  from urllib.request import urlopen # Python3  from urllib.error import HTTPErrorfrom bs4 import BeautifulSoupimport sysdef 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 titletitle = getTitle("http://www.pythonscraping.com/exercises/exercise1.html")if title == None:  print("Title could not be found")else:  print(title)

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武林站长站。