XML-SAX

XML解析技术常用的就是DOM和SAX,DOM(Document Object Model)即文档对象模型,将xml文件整体解析为内存中的特定数据结构,然后再对该内存中的数据机构进行操作(增删改查),SAX(Simple API for XML)即简单XML API,以流的方式读取xml文档,并以事件驱动来处理节点,其只能查询,无法对xml进行更新操作。

DOM4J是借助SAX方式来构建DOM对象,jdk中自带的DOM(com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl)的API是w3c标准API,DOM4J则是自己独有的一套API,二者的内在实现也略有不同,jdk的DOM需要将xml全部读入内存再进行解析,DOM4J则使用SAX进行流式解析(事件驱动)。

 

 1  <?xml version="1.0" encoding="UTF-8"?>
 2  <DocumentElement param="value">
 3      <FirstElement>
 4          &#xb6; Some Text
 5      </FirstElement>
 6      <?some_pi some_attr="some_value"?>
 7      <SecondElement param2="something">
 8          Pre-Text <Inline>Inlined text</Inline> Post-text.
 9      </SecondElement>
10 </DocumentElement>

SAX会这样解析上面的xml文件:

  • XML Element start, named DocumentElement, with an attribute param equal to "value"
  • XML Element start, named FirstElement
  • XML Text node, with data equal to "&#xb6; Some Text" (note: certain white spaces can be changed)
  • XML Element end, named FirstElement
  • Processing Instruction event, with the target some_pi and data some_attr="some_value" (the content after the target is just text; however, it is very common to imitate the syntax of XML attributes, as in this example)
  • XML Element start, named SecondElement, with an attribute param2 equal to "something"
  • XML Text node, with data equal to "Pre-Text"
  • XML Element start, named Inline
  • XML Text node, with data equal to "Inlined text"
  • XML Element end, named Inline
  • XML Text node, with data equal to "Post-text."
  • XML Element end, named SecondElement
  • XML Element end, named DocumentElement

 

 

下面就使用SAX对一个spring配置文件简单解析。

 

spring配置文件

1 <spring:beans xmlns:spring="http://www.springframework.org/schema/beans"
2   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
3   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
4   <spring:bean id="myBean" class="com.zyong.spring.beanfactory.MyBean"/>
5 </spring:beans>

 

测试方法:

1 String file = ClassLoader.getSystemResource("spring/spring-test.xml").getFile();
2 com.sun.org.apache.xerces.internal.parsers.SAXParser saxParser = new com.sun.org.apache.xerces.internal.parsers.SAXParser();
3 saxParser.setContentHandler(new MyHandler());
4 saxParser.parse(new InputSource(file));

 

 

事件处理器:

 1 private class MyHandler extends DefaultHandler {
 2 
 3   @Override
 4   public void startDocument() throws SAXException {
 5     System.out.println("start document -> parse begin");
 6   }
 7 
 8   @Override
 9   public void endDocument() throws SAXException {
10         System.out.println("end document -> parse finished");
11   }
12 
13   @Override
14   public void startElement(String uri, String localName, String qName,
15                            Attributes attributes) throws SAXException {
16     System.out.println("start element-----------");
17     System.out.println("    localName: " + localName);
18     System.out.println("    qName: " + qName);
19   }
20 
21   @Override
22   public void characters(char[] ch, int start, int length)
23           throws SAXException {
24     System.out.println("characters-----------");
25     System.out.println("    ch: " + ch);
26     System.out.println("    start: " + start);
27     System.out.println("    length: " + length);
28   }
29 
30   @Override
31   public void endElement(String uri, String localName, String qName)
32           throws SAXException {
33     System.out.println("end element-----------");
34     System.out.println("    localName: " + localName);
35     System.out.println("    qName: " + qName);
36 
37   }
38 }

 

输出:

start document -> parse begin
start element-----------
    localName: beans
    qName: spring:beans
characters-----------
    ch: [C@4cc77c2e
    start: 272
    length: 5
start element-----------
    localName: bean
    qName: spring:bean
end element-----------
    localName: bean
    qName: spring:bean
characters-----------
    ch: [C@4cc77c2e
    start: 348
    length: 5
start element-----------
    localName: bean
    qName: spring:bean
end element-----------
    localName: bean
    qName: spring:bean
characters-----------
    ch: [C@4cc77c2e
    start: 436
    length: 1
end element-----------
    localName: beans
    qName: spring:beans
end document -> parse finished
View Code

 

参考:http://blog.csdn.net/u011179993/article/details/47415603

  http://www.cnblogs.com/mengdd/archive/2013/06/02/3114177.html

posted @ 2017-08-14 18:53  holoyong  阅读(395)  评论(0编辑  收藏  举报