#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)

{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'}