python sax解析xml

#books.xml
<catalog>
    <book isbn="0-596-00128-2">
        <title>Python &amp; XML</title>
        <title>Python &amp; HTML</title>
        <date>December 2001</date>
        <author>Jones, Drake</author>
    </book>
    <book isbn="0-596-15810-6">
        <title>Programming Python, 4th Edition</title>
        <date>October 2010</date>
        <author>Lutz</author>
    </book>
    <book isbn="0-596-15806-8">
        <title>Learning Python, 4th Edition</title>
        <date>September 2009</date>
        <author>Lutz</author>
    </book>
    <book isbn="0-596-15808-4">
        <title>Python Pocket Reference, 4th Edition</title>
        <date>October 2009</date>
        <author>Lutz</author>
    </book>
    <book isbn="0-596-00797-3">
        <title>Python Cookbook, 2nd Edition</title>
        <date>March 2005</date>
        <author>Martelli, Ravenscroft, Ascher</author>
    </book>
    <book isbn="0-596-10046-9">
        <title>Python in a Nutshell, 2nd Edition</title>
        <date>July 2006</date>
        <author>Martelli</author>
    </book>
    <!-- plus many more Python books that should appear here -->
</catalog>

#conding:utf-8
# -*- coding:utf-8 -*-
__author__ = 'hdfs'
'''
总的来说 sax解析xml 进行3个阶段 sax是线性解析对于大的xml会很有效率
'''
import xml.sax,xml.sax.handler,pprint
class BookHandler(xml.sax.handler.ContentHandler):
    def __init__(self):
        self.inTitle=False
        self.mapping={}

    def startElement(self, name, attrs):
        #book标签开始
        if name=="book":
            self.buffer=""
            self.isbn=attrs["isbn"]
        #title标签开始
        elif name=="title":
            self.inTitle=True

    def characters(self,data):
        #如果真的进入buffer 关联多个子节点的数据
        if self.inTitle:
            self.buffer+=data
    #结束一个元素的遍历
    def endElement(self,name):
        if name=="title":
            self.inTitle=False
            self.mapping[self.isbn]=self.buffer

parser=xml.sax.make_parser()
handler=BookHandler()
parser.setContentHandler(handler)
parser.parse('books.xml')
pprint.pprint(handler.mapping)

result:

{u'0-596-00128-2': u'Python & XMLPython & HTML',
 u'0-596-00797-3': u'Python Cookbook, 2nd Edition',
 u'0-596-10046-9': u'Python in a Nutshell, 2nd Edition',
 u'0-596-15806-8': u'Learning Python, 4th Edition',
 u'0-596-15808-4': u'Python Pocket Reference, 4th Edition',
 u'0-596-15810-6': u'Programming Python, 4th Edition'}