二、SAX解析XML

为解决DOM的问题，出现了SAX。SAX ，事件驱动。当解析器发现元素开始、元素结束、文本、文档的开始或结束等时，发送事件，程序员编写响应这些事件的代码，保存数据。

优点：不用事先调入整个文档，占用资源少；SAX解析器代码比DOM解析器代码小，适于Applet，下载。

缺点：不是持久的；事件过后，若没保存数据，那么数据就丢了；无状态性；从事件中只能得到文本，但不知该文本属于哪个元素；

使用场合：Applet;只需XML文档的少量内容，很少回头访问；机器内存少；

package FourWayToAnalyticXml;

 

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

 

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.parsers.SAXParser;

import javax.xml.parsers.SAXParserFactory;

 

import org.xml.sax.Attributes;

import org.xml.sax.SAXException;

import org.xml.sax.helpers.DefaultHandler;

 

import Interface.XmlDocument;

 * @author  SAX文档解析

public class SAXToAnalyticXml implements XmlDocument {

//        String fileName = "domparserXml";

public static void main(String[] args) {

// TODO Auto-generated method stub

SAXToAnalyticXml sax = new SAXToAnalyticXml();

sax.createXml("domparserXml");

sax.parserXml("domparserXml");

}

public void createXml(String fileName) {

System.out.println("<<" + fileName + ">>");

}

 

public void parserXml(String fileName) {

SAXParserFactory saxfac = SAXParserFactory.newInstance();

 

try {

 

SAXParser saxparser = saxfac.newSAXParser();

 

InputStream is = new FileInputStream(fileName);

 

saxparser.parse(is, new MySAXHandler());

 

} catch (ParserConfigurationException e) {

 

e.printStackTrace();

 

} catch (SAXException e) {

 

e.printStackTrace();

 

} catch (FileNotFoundException e) {

 

e.printStackTrace();

 

} catch (IOException e) {

 

e.printStackTrace();

 

}

 

}

 

}

 

class MySAXHandler extends DefaultHandler {

 

boolean hasAttribute = false;

 

Attributes attributes = null;

 

public void startDocument() throws SAXException {

 

System.out.println("文档开始打印了");

 

}

 

public void endDocument() throws SAXException {

 

System.out.println("文档打印结束了");

 

}

 

public void startElement(String uri, String localName, String qName,

 

Attributes attributes) throws SAXException {

 

if (qName.equals("employees")) {

 

return;

 

}

 

if (qName.equals("employee")) {

 

System.out.println(qName);

 

}

 

if (attributes.getLength() > 0) {

 

this.attributes = attributes;

 

this.hasAttribute = true;

 

}

 

}

 

public void endElement(String uri, String localName, String qName)

 

throws SAXException {

 

if (hasAttribute && (attributes != null)) {

 

for (int i = 0; i < attributes.getLength(); i++) {

 

System.out.println(attributes.getQName(0)

+ attributes.getValue(0));

 

}

 

}

 

}

 

public void characters(char[] ch, int start, int length)

 

throws SAXException {

 

System.out.println(new String(ch, start, length));

 

}

 

 

}