Python爬虫学习1

#coding=utf-8
from urllib2 import urlopen
from bs4 import BeautifulSoup
import urllib2
url="http://pythonscraping.com/pages/page1.html"
def getTitle(url):
    """
    说明一下，处理异常的过程
    1.检查是否能打开网页 异常类型为urllib2.HTTPError
    2.检查是否服务器存在，不存在返回空，那么在read是返回AttributeError
    :param url:
    :return:
    """
    try:

        html=urlopen(url)
    except urllib2.HTTPError as e:
#这里的错误是网页不存在
        print e
        return None
    try:
        bsobj=BeautifulSoup(html.read(),"html.parser")
        title=bsobj.body.h1
    except AttributeError as e:
        return None
    return title
title=getTitle(url)
if title is None:
    print "Title could not be found"
else:
    print title