Python—使用xml.sax解析xml文件

什么是sax？

SAX是一种基于事件驱动的API。

利用SAX解析XML文档牵涉到两个部分:解析器和事件处理器。

解析器负责读取XML文档,并向事件处理器发送事件,如元素开始跟元素结束事件;

而事件处理器则负责对事件作出相应,对传递的XML数据进行处理。

sax适于处理下面的问题：

1、对大型文件进行处理；
2、只需要文件的部分内容，或者只需从文件中得到特定信息；
3、想建立自己的对象模型的时候。

在python中使用sax方式处理xml要先引入xml.sax中的parse函数，还有xml.sax.handler中的ContentHandler。

movies.xml:需要解析的xml文件，上一篇博客中使用dom解析的一样

<collection shelf="New Arrivals">

<movie title="Enemy Behind">

   <type>War, Thriller</type>

   <format>DVD</format>

   <year>2003</year>

   <rating>PG</rating>

   <stars>10</stars>

   <description>Talk about a US-Japan war</description>

</movie>

<movie title="Transformers">

   <type>Anime, Science Fiction</type>

   <format>DVD</format>

   <year>1989</year>

   <rating>R</rating>

   <stars>8</stars>

   <description>A schientific fiction</description>

</movie>

<movie title="Trigun">

   <type>Anime, Action</type>

   <format>DVD</format>

   <episodes>4</episodes>

   <rating>PG</rating>

   <stars>10</stars>

   <description>Vash the Stampede!</description>

</movie>

<movie title="Ishtar">

   <type>Comedy</type>

   <format>VHS</format>

   <rating>PG</rating>

   <stars>2</stars>

   <description>Viewable boredom</description>

</movie>

</collection>

xmltest.py:解析代码如下

# -*- coding:UTF-8 -*-

'''

Created on 2015年9月10日

@author: xiaowenhui

'''

import xml.sax

#第二种方法，sax解析

class MovieHandler(xml.sax.ContentHandler):  #继承于xml.sax.ContentHandler类

    def __init__(self):

        self.CurrentData = ""

        self.type = ""

        self.format = ""

        self.year = ""

        self.episodes = ""

        self.rating = ""

        self.stars = ""

        self.description = ""

        self.title = ""

    # 元素开始事件处理

    def startElement(self, tag, attributes):

        self.CurrentData = tag

        if tag == "movie":

            print "*****Movie*****"

            self.title = attributes["title"]

            print "Title:", self.title

    # 内容事件处理

    def characters(self, content):

        if self.CurrentData == "type":

            self.type = content

        elif self.CurrentData == "format":

            self.format = content

        elif self.CurrentData == "year":

            self.year = content

        elif self.CurrentData == "episodes":

            self.episodes = content

        elif self.CurrentData == "rating":

            self.rating = content

        elif self.CurrentData == "stars":

            self.stars = content

        elif self.CurrentData == "description":

            self.description = content

    # 元素结束事件处理

    def endElement(self, tag):

        if self.CurrentData == "type":

            print "Type:", self.type

        elif self.CurrentData == "format":

            print "Format:", self.format

        elif self.CurrentData == "year":

            print "Year:", self.year

        elif self.CurrentData == "episodes":

            print "Episodes:", self.episodes

        elif self.CurrentData == "rating":

            print "Rating:", self.rating

        elif self.CurrentData == "stars":

            print "Stars:", self.stars

        elif self.CurrentData == "description":

            print "Description:", self.description

# 创建一个 XMLReader

parser = xml.sax.make_parser()

# turn off namepsaces

parser.setFeature(xml.sax.handler.feature_namespaces, 0)

# 重写 ContextHandler

Handler = MovieHandler()

parser.setContentHandler( Handler )

parser.parse("movies.xml")

输出结果如下：

疑问：不知道为什么会多输出一个description，可能是sax解析的时候哪里写的不对，现在还没找到原因，我把

 elif self.CurrentData == "description":

 print "Description:", self.description

改成

 elif self.CurrentData == "description":

 print  self.description
后就没有输出“description”，只输出了self.description这个参数

*****Movie*****

Title: Enemy Behind

Type: War, Thriller

Format: DVD

Year: 2003

Rating: PG

Stars: 10

description: Talk about a US-Japan war

description: 

*****Movie*****

Title: Transformers

Type: Anime, Science Fiction

Format: DVD

Year: 1989

Rating: R

Stars: 8

description: A schientific fiction

description: 

*****Movie*****

Title: Trigun

Type: Anime, Action

Format: DVD

Episodes: 4

Rating: PG

Stars: 10

description: Vash the Stampede!

description: 

*****Movie*****

Title: Ishtar

Type: Comedy

Format: VHS

Rating: PG

Stars: 2

description: Viewable boredom

description: 

description:

巴特西

Python—使用xml.sax解析xml文件

什么是sax？

movies.xml:需要解析的xml文件，上一篇博客中使用dom解析的一样

xmltest.py:解析代码如下

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